阅读说明：本技术 一种并联型双叉车同步控制装置 (Parallel double-forklift synchronous control device ) 是由 顾敏明 龚嘉豪 张博 唐丽娟 于 2021-08-03 设计创作，主要内容包括：本发明公开一种并联型双叉车同步控制装置,包括机械结构与控制结构两个部分,所述机械结构包括电动托盘叉车车架和货叉两个部分,车架包括通过与车头固定结构连接的承载桥、通过液压缸连接在承载桥之上的叉车顶盖、承载桥之下刚性连接的太阳齿轮、啮合在太阳齿轮周围的转向传动齿轮和旋转编码器传动齿轮、驱动轮、驱动轮两侧的传动抬升连杆,所述货叉与叉车头部固定连接,货叉上安装从动轮；所述控制结构包括领导者叉车控制系统、跟随者叉车控制系统、电驱动装置、升降液压系统和无线信号遥控器。本发明解决传统机械耦合并联叉车机械连接件扭曲的问题,能够使得两辆或者多辆叉车能够完全同步运动。(The invention discloses a parallel double-forklift synchronous control device, which comprises a mechanical structure and a control structure, wherein the mechanical structure comprises an electric pallet forklift frame and a pallet fork, the frame comprises a bearing bridge connected with a head fixing structure, a forklift top cover connected above the bearing bridge through a hydraulic cylinder, a sun gear rigidly connected below the bearing bridge, a steering transmission gear and a rotary encoder transmission gear which are meshed around the sun gear, a driving wheel and transmission lifting connecting rods on two sides of the driving wheel, the pallet fork is fixedly connected with the head of the forklift, and a driven wheel is mounted on the pallet fork; the control structure comprises a leader forklift control system, a follower forklift control system, an electric driving device, a lifting hydraulic system and a wireless signal remote controller. The invention solves the problem of distortion of mechanical connecting pieces of the traditional mechanical coupling parallel forklift, and can ensure that two or more forklifts can completely synchronously move.)

1. The parallel double-forklift synchronous control device is characterized by comprising a mechanical structure and a control structure, wherein the mechanical structure comprises a carrier bridge (7) connected with a forklift frame (1) through a forklift head fixing structure, a forklift top cover connected to the carrier bridge (7) through a hydraulic cylinder (4), a sun gear (16) rigidly connected below the carrier bridge (7), a steering transmission gear (8) and a rotary encoder transmission gear (9) which are meshed around the sun gear (16), a driving wheel (14) and transmission lifting connecting rods (17) on two sides of the driving wheel, the fork (18) is fixedly connected with the head of the forklift, and a driven wheel (19) is mounted on the fork (18);

the control structure comprises a leader forklift control system (24), a follower forklift control system (25), an electric drive device, a lifting hydraulic system and a wireless signal remote controller, wherein the leader forklift control system (24) and the follower forklift control system (25) comprise a main control panel, a limit switch and an absolute value rotary encoder, the leader forklift control system (24) further comprises a remote control signal receiver, the follower forklift control system (25) further comprises an auxiliary control panel, and the auxiliary control panel is connected with a groove-shaped laser sensor and a laser ranging sensor (28);

the line groove type laser sensor comprises a line type laser generator (29) and a groove type laser receiver (27), wherein the line type laser generator (29) is fixed on one forklift and used for emitting laser, the groove type laser receiver (27) is fixed on the other forklift, and electric signals of relative positions are generated according to the laser received by different hole positions;

the main control board is connected with the straight servo system and the steering servo system; the main control panel is provided with a main controller, the electric drive device is a power supply fixed in the lower part of the top cover of the forklift, and the power supply supplies power to the whole forklift synchronous control device;

the lifting hydraulic system comprises a hydraulic motor (5), a hydraulic cylinder (4) and an oil tank at the bottom of the hydraulic cylinder; the lifting mode is that a user sends a remote control signal to the hydraulic motor (5), the hydraulic motor (5) fills oil in the oil tank into the hydraulic cylinder (4) through the oil inlet, the hydraulic cylinder (4) lifts to lift the forklift platform, and the descending mode is that the user sends the remote control signal to open an oil outlet valve at the bottom of the hydraulic cylinder (4) and the forklift platform descends;

the straight servo system comprises a straight servo motor driver (3) and a straight servo motor (15), a user sends straight to a remote controller signal receiver (6) through a wireless signal of a remote controller, the remote controller signal receiver (6) converts the wireless signal into a straight analog quantity to be transmitted to a main controller (31), the main controller (31) acquires the speed information intention of the user through AD acquisition, the main controller (31) sends an instruction to the straight servo driver (3) in the advancing function, the straight servo motor (15) is controlled by the straight servo driver (3) to realize the straight movement of a driving wheel (14), and a driven wheel (19) moves along with the movement of the driving wheel (14);

turn to servo including turning to servo motor driver (2), turn to servo motor (11) two parts, the user turns to for remote controller signal receiver (6) through the wireless signal transmission of remote controller, remote controller signal receiver (6) turn to analog quantity with wireless signal conversion and send main control unit (31), main control unit (31) acquire user's angle information intention through AD, turn to the function and send the instruction for turning to servo driver (2) by main control unit (31), turn to servo motor (11) by turning to servo driver (2) control again, it increases output torque to turn to planetary reducer (10) connection (11), realize the motion that turns to of drive wheel (14) through turning to drive gear (8) with sun gear (16) meshing.

2. The parallel type dual forklift synchronous control device according to claim 1, wherein the main controller is connected with an AD acquisition circuit, the AD acquisition circuit comprises a resistor R1, a resistor R2, a resistor R3, a resistor R4, a resistor R5, a resistor R6, a capacitor C1, a capacitor C2, a capacitor C3 and a transient suppression diode DR1, an input InputSignal of the acquisition circuit is connected with a direct analog output of the remote control signal receiver, the other end of the resistor R2 connected in series with the input end is connected with a non-inverting input INA + of the operational amplifier LM358, a resistor R2 is connected with the transient suppression diode DR1, a resistor R1, a resistor R3 and a capacitor C1, the transient suppression diode DR1 is connected with the resistor R2 and then the other end is connected with GND, the other end of the resistor R1 is connected with GND R2 and the other end of the resistor R3 is connected with the capacitor C1 and the other end of the resistor R2 and the other end is connected with a GND of the positive power supply of the operational amplifier LM 5, meanwhile, the capacitor C2 is connected, the other end of the capacitor C2 is connected with GND, the power supply of the operational amplifier LM358 is negatively connected with GND, the inverting input end INA-of the operational amplifier LM358 is connected with the output end of the operational amplifier LM358, the output end of the operational amplifier LM358 is connected with the resistor R4, the other end of the resistor R4 is respectively connected with the resistor R5 and the resistor R6, the other end of the resistor R5 is respectively connected with GND and the capacitor C3, the other end of the resistor R6 is respectively connected with the other end of the C3 and a signal output end outputSignal, and the output end outputSignal is connected with an ADC pin of the main controller.

3. The parallel type double-forklift synchronization control device as claimed in claim 1, wherein said master controller is connected to the linear servo motor drive, the steering servo drive, the rotary encoder, and the sub-controller through a TTL to 485 communication circuit, the TTL to 485 communication circuit including resistors R1, R2, R7, resistors R9, R10, resistors R13, R14, resistors R17, a capacitor C3, transient suppression diodes DR1, DZ1, DZ2, a thermistor PTC2, a thermistor PTC3, an input MODBUS-RDE connected to an IO pin of the master controller for controlling a master control and a transmission selection of the RS485 circuit, an input MODBUS-RX connected to a serial port receiving pin of the master controller, an input MODBUS-TX connected to a serial port transmitting pin of the slave controller, the other end of the resistor R2 connected in series to the input MODBUS-RDE is simultaneously connected to a receiver output enable DE port of the SP485 chip, the other end of a resistor R1 connected in series with an input end MODBUS-RX is simultaneously connected with a receiver output port RO of an SP485 chip, the other end of a resistor R2 connected in series with an input end MODBUS-TX is simultaneously connected with a driver input port DI of the SP485 chip, the A of the SP485 chip is simultaneously connected with R13 and R9, the other end of R9 is simultaneously connected with a power supply port VCC of 5V, C3 and the SP485 chip, the other end of R13 is simultaneously connected with C5, a transient suppression diode DZ1, a transient suppression diode DR1, a resistor R17 and a thermistor PTC2, the other end of a capacitor C3 is simultaneously connected with the other end of C5, the other end of a transient suppression diode DZ1 and GND, the B of the SP485 chip is simultaneously connected with resistors R14 and R10, the other end of R10 is simultaneously connected with a GND port of the SP485 chip, a capacitor C6, a transient suppression diode DZ2 and GND, the other end of the resistor R14 is simultaneously connected with the other end of the capacitor C6 and the transient suppression diode DZ2, The other end of the transient suppression diode DR1, the other end of the resistor R17 and the thermistor PTC3 are connected, the other end of the thermistor PTC2 is connected with MODBUS-B, the other end of the thermistor PTC3 is connected with MODBUS-A, the MODBUS-A is connected with the linear motor servo drive RS485A phase, and the MODBUS-B is connected with the linear motor servo drive RS485B phase.

Technical Field

The invention relates to the technical field of electric pallet forklifts, in particular to a parallel double-forklift synchronous control device.

Background

The forklift is an engineering vehicle widely applied to ports, stations, airports, goods yards, factory workshops, warehouses, circulation centers and distribution centers, and is necessary efficient equipment for loading and unloading, carrying operation, pallet transportation and container transportation of pallet goods in cabins, carriages and containers. Forklifts can generally be divided into two broad categories: diesel fork truck, electric fork truck, and the factor influence such as artifical the substitution of benefiting, environmental protection upgrading, electronic upgrading, electric fork truck is becoming the mainstream transport vehicle of handling trade and is being used for replacing diesel fork truck.

Due to the size limitation of a single forklift, the single forklift mainly still stays in the transportation and sending of small and medium pieces. When the pallet fork truck is used for carrying large-size or heavy-weight goods, the pallet fork truck of a large model needs to be replaced to be matched with the pallet fork truck. Different tray fork truck models are suitable for carrying goods with different sizes or different weights, if the size and the weight of the goods to be carried are changed frequently, the tray fork trucks with different models need to be prepared frequently, and the fixed investment of the manufacturing industry is increased. If can be through the parallelly connected synchronous operation of small-size fork truck, with the above problem of effectual solution.

Disclosure of Invention

The invention aims to solve the problem of distortion of mechanical connecting pieces of a traditional mechanical coupling parallel forklift and provides a parallel electronic coupling step control device for double forklifts, which is high in synchronization precision, large in effective load and low in cost.

A parallel double-forklift synchronous control device comprises a mechanical structure and a control structure, wherein the mechanical structure comprises an electric pallet forklift frame and a pallet fork, the frame comprises a bearing bridge connected with a head fixing structure, a forklift top cover connected above the bearing bridge through a hydraulic cylinder, a sun gear rigidly connected below the bearing bridge, a steering transmission gear and a rotary encoder transmission gear which are meshed around the sun gear, a driving wheel and transmission lifting connecting rods at two sides of the driving wheel, the pallet fork is fixedly connected with the head of the forklift, and a driven wheel is mounted on the pallet fork;

the control structure comprises a leader forklift control system, a follower forklift control system, an electric drive device, a lifting hydraulic system and a wireless signal remote controller, wherein the leader forklift control system and the follower forklift control system respectively comprise a main control panel, a limit switch and an absolute value rotary encoder;

the line groove type laser sensor comprises a line type laser generator and a groove type laser receiver, wherein the line type laser generator is fixed on one forklift and used for emitting laser, and the groove type laser receiver is fixed on the other forklift and used for generating electric signals of relative positions according to the laser received by different hole sites;

the main control board is connected with the straight servo system and the steering servo system; the main control panel is provided with a main controller, the electric drive device is a power supply fixed in the lower part of the top cover of the forklift, and the power supply supplies power to the whole forklift synchronous control device;

the lifting hydraulic system comprises a hydraulic motor, a hydraulic cylinder and an oil tank at the bottom of the hydraulic cylinder; the lifting mode is that a user sends a remote control signal to the hydraulic motor, the hydraulic motor fills oil in the oil tank into the hydraulic cylinder through the oil inlet, the hydraulic cylinder lifts to lift the forklift platform, and the descending mode is that the user sends the remote control signal to open an oil outlet valve at the bottom of the hydraulic cylinder and the forklift platform descends;

the straight servo system comprises a straight servo motor driver and a straight servo motor, wherein a user sends straight to a remote controller signal receiver through a wireless signal of a remote controller, the remote controller signal receiver converts the wireless signal into a straight analog quantity to be transmitted to a main controller, the main controller acquires the speed information intention of the user through AD acquisition, the main controller sends an instruction to the straight servo driver for a forward function, the straight servo motor is controlled by the straight servo driver to realize the straight motion of a driving wheel, and a driven wheel moves along with the motion of the driving wheel;

the steering servo system comprises a steering servo motor driver and a steering servo motor, a user sends steering signals to a remote controller signal receiver through a wireless signal of a remote controller, the remote controller signal receiver converts the wireless signals into steering analog quantity to be transmitted to a main controller, the main controller acquires angle information intention of the user through AD acquisition, a steering function sends instructions to the steering servo driver through the main controller, the steering servo motor is controlled by the steering servo driver, the steering servo motor is connected with a planetary reducer to increase output torque, and steering movement of a driving wheel is achieved through a steering transmission gear meshed with a sun gear.

The main controller is connected with an AD acquisition circuit, the AD acquisition circuit comprises a resistor R1, a resistor R2, a resistor R3, a resistor R4, a resistor R5, a resistor R6, a capacitor C1, a capacitor C2, a capacitor C3 and a transient suppression diode DR1, an input end InputSignal of the acquisition circuit is connected with a straight-line analog quantity output of the remote control signal receiver, the other end of the resistor R2 connected in series with the input end is connected with a non-inverting input end INA + of an operational amplifier LM358, a resistor R2 is connected with the transient suppression diode 58DR 24, the resistor R1, the resistor R3 and the capacitor C1 at the same time, the other end of the transient suppression diode DR1 connected with a resistor R2 is connected with GND, the resistor R56 is connected with a resistor R2, the other end of the resistor R3 and the capacitor C1 are connected with the resistor R2 at the same time, the power supply of the operational amplifier LM358 is connected with 5V, the other end of the capacitor C2 is connected with GND, and GND is connected with the GND of the operational amplifier LM 2, the inverting input terminal INA-of the operational amplifier LM358 is connected with the output terminal of the operational amplifier LM358, the output terminal of the operational amplifier LM358 is connected with the resistor R4, the other end of the resistor R4 is connected with the resistor R5 and the resistor R6 respectively, the other end of the resistor R5 is connected with the GND and the capacitor C3 respectively, the other end of the resistor R6 is connected with the other end of the capacitor C3 and the signal output terminal outputSignal respectively, and the output terminal outputSignal is connected with an ADC pin of the main controller.

The main controller is connected with a straight servo motor drive, a steering servo drive, a rotary encoder and a secondary controller through a TTL to 485 communication circuit, the TTL to 485 communication circuit comprises resistors R1, R2, R7, resistors R9, R10, resistors R13, R14, resistors R17, a capacitor C3, transient suppression diodes DR1, DZ1, DZ2, a thermistor PTC2 and a thermistor PTC3, an input terminal MODBUS-RDE is connected with an IO pin of the main controller and used for controlling receiving and sending selection of an RS485 circuit, an input terminal MODBUS-RX is connected with a serial port receiving pin of the main controller, an input terminal MODBUS-TX is connected with a serial port sending pin of the main controller, the other end of the resistor R2 connected in series with the input terminal BUS-RDE is simultaneously connected with a receiver output enable port RE and a driver enable DE port of an SP485 chip, the other end of the resistor R1 connected in series with the input terminal BUS-RX is simultaneously connected with an RO output port of the SP485 chip, the other end of a resistor R2 connected in series with an input end MODBUS-TX is simultaneously connected with a driver input port DI of an SP485 chip, the A of the SP485 chip is simultaneously connected with R13 and R9, the other end of R9 is simultaneously connected with a power supply port VCC of the 5V, C3 and SP485 chip, the other end of R13 is simultaneously connected with C5, a transient suppression diode DZ1, a transient suppression diode DR1, a resistor R17 and a thermistor PTC2, the other end of a capacitor C3 is simultaneously connected with the other end of C5, the other end of a transient suppression diode DZ1 and GND, the B of the SP485 chip is simultaneously connected with resistors R14 and R10, the other end of R10 is simultaneously connected with a GND port of the SP485 chip, a capacitor C6, a transient suppression diode DZ2 and GND, the other end of a resistor R7 is simultaneously connected with the other end of a capacitor C6, the other end of a transient suppression diode DZ2, the other end of a transient suppression diode DR 2, the other end of a thermistor DR 2, the other end of a PTC2 and a PTC2 are connected with a MODBUS-B resistor, the other end of the thermistor PTC3 is connected with an MODBUS-A, the MODBUS-A is connected with A straight motor servo drive RS485A phase, and the MODBUS-B is connected with A straight motor servo drive RS485B phase.

The invention solves the problem of distortion of mechanical connecting pieces of the traditional mechanical coupling parallel forklift, and can ensure that two or more forklifts can completely synchronously move.

Drawings

Fig. 1 is a system configuration of a parallel type double-forklift synchronous control device according to the present invention.

Fig. 2 is a schematic diagram of a main controller of the parallel type electric pallet truck of the present invention.

Fig. 3 is an AD acquisition circuit diagram of the forklift truck of the present invention.

Fig. 4 is a circuit diagram of TTL to 485 communication of the forklift truck.

Fig. 5 is a schematic structural diagram of the double-forklift synchronization system.

Fig. 6 is a mechanical structure view of the parallel type electric pallet truck of the present invention.

Fig. 7 is a schematic view of the lift link structure of the forklift of the present invention.

Fig. 8 is a circuit diagram of the digital quantity acquisition of the forklift truck.

Fig. 9 is a circuit diagram of the relay output of the forklift of the present invention.

Fig. 10 is a schematic view of the calculated ackerman angle of the forklift of the present invention.

Fig. 11 is a flow chart of the basic synchronous movement method of the forklift truck.

Fig. 12 is a flowchart of a method for adjusting the longitudinal movement deviation of the forklift according to the present invention.

Fig. 13 is a schematic view of the truck of the present invention showing large corner lateral deflection.

Fig. 14 is a schematic view of the forklift of the present invention showing small lateral deflection of the corner.

Fig. 15 shows a method for adjusting lateral movement deviation of a forklift according to the present invention.

Fig. 16 is a schematic view showing a horizontal deviation of the forklift of the present invention.

Fig. 17 shows a method for adjusting the height deviation of the forklift according to the present invention.

Detailed Description

As shown in fig. 1, the system structure of the parallel type double-forklift synchronous control device comprises a leader forklift control system 24, a follower forklift control system 25 and a 433M wireless signal remote controller. The leader forklift control system 24 comprises a main control board, a remote control signal receiver, a straight servo motor drive, a straight servo motor, a steering servo motor drive, a steering servo motor, a limit switch and an absolute value rotary encoder. The follower forklift control system 25 comprises a main control panel, an auxiliary control panel, a straight servo motor drive, a straight servo motor, a steering servo motor drive, a steering servo motor, a limit switch, an absolute value rotary encoder, a slot type laser ranging module and a laser ranging sensor.

The main control panel is provided with a main controller, as shown in fig. 2, the main controller comprises 4 RS485 interfaces, a CAN bus interface, two ADC interfaces and two digital quantity acquisition interfaces.

The 433M wireless signal remote controller comprises: a motion rocker, a lifting button, a descending button, a buzzer button and an emergency stop switch. When the motion rocker shakes, the remote controller sends the straight-moving speed information and the steering angle information to the remote control signal receiver. When the lifting button, the descending button, the buzzer button and the emergency stop switch are pressed down, the remote controller sends lifting, descending, buzzer and emergency stop instructions to the remote control signal receiver.

The remote control signal receiver converts the wireless signals sent by the 433M wireless signal remote controller into two paths of 4-20mA analog quantity for direct movement and turning and two paths of digital quantity for platform ascending and platform descending, and transmits the two paths of digital quantity to the main controller, and meanwhile, the buzzer instruction and the emergency stop instruction are processed in the remote control signal receiver.

The two paths of 4-20mA analog quantities output by the remote control signal receiver respectively control the motion of the straight motor and the motion of the steering motor. The motion rocker is shifted left and right to control the steering servo motor to move, and is shifted up and down to control the straight servo motor to move.

The design of the straight-going command is introduced, the output current of the motion rocker in the neutral state is 12mA, the dead zone current is set to be 11.5-12.5mA for realizing software jitter elimination, and at the moment, the motion of the remote controller does not control the motion of the straight-going servo motor. The straight servo motor advances at 4-11.5mA and retreats at 12.5-20 mA, and when the output current is 4mA, the straight servo motor realizes the maximum advancing speed, and the advancing speed gradually returns to zero from the maximum speed along with the gradual increase of the output current to 11.5 mA. When the output current is 20mA, the maximum speed of the backward movement of the straight servo motor is realized, and the backward speed gradually returns to zero from the maximum value along with the gradual decrease of the output current to 12.5 mA. The remote controller can realize stepless speed regulation under the design.

The design of a steering command is introduced, the output current of the motion rocker in a neutral state is 12mA, the dead zone current is set to be 11.5-12.5mA for realizing software shake elimination, and the motion of the steering servo motor is not controlled by the motion of the remote controller. The steering servo motor rotates to the right at 4-11.5mA and rotates to the left at 12.5-20 mA. When the output current is 4mA, the steering servo motor realizes the maximum angle of the right turn, and the rotation angle gradually returns to zero from the maximum angle of the right turn along with the gradual increase of the output current to 11.5 mA. When the output current is 20mA, the steering servo motor realizes the maximum angle of the left turn, and the rotation angle gradually returns to zero from the maximum angle of the left turn along with the gradual decrease of the output current to 12.5 mA. The remote controller can realize stepless steering under the design.

Since the control object of the system is a forklift for carrying heavy objects, the importance of safety and stability to the whole system is self-evident, and if analog signals are directly input to the main controller. Potential safety hazards can be caused, so that the safety of the system is ensured by designing an anti-surge circuit, an isolation circuit and a filter circuit, and the AD acquisition circuit is designed for the purpose.

As shown in fig. 3, in the AD acquisition circuit diagram of the forklift, the resistance R1 is 200 Ω, the resistances R2, R5 and R6 are 1K Ω, the resistance R3 is 1M Ω, the resistance R4 is 3K Ω, the capacitances C1, C2 and C3 are 0.1uf, the maximum reverse standby voltage of the transient suppression diode DR1 is 6.5V, the input InputSignal is connected to the direct analog output of the remote control signal receiver of fig. 2, the other end of the resistance R2 connected in series to the input terminal is connected to the non-inverting input terminal INA + of the operational amplifier LM358, the resistance R2 is connected to the transient suppression diode DR1, the resistance R1, the resistance R3 and the capacitance C1 at the same time, the transient suppression diode DR1 is connected to the resistance R2 and then the other end is connected to GND, the resistance R2 is connected to the other end of the resistance R2 and GND, the resistance R1 is connected to the other end of the resistance R2 and then to the positive voltage of the operational amplifier LM 5, the other end of the C2 is connected with a capacitor C2, the other end of the C2 is connected with GND, the power supply of the operational amplifier LM358 is negatively connected with GND, the inverting input end INA-of the operational amplifier LM358 is connected with the output end of the operational amplifier, the output end of the operational amplifier is connected with a resistor R4, the other end of the resistor R4 is connected with a resistor R5 and a resistor R6 respectively, the other end of the resistor R5 is connected with GND and a capacitor C3 respectively, the other end of the resistor R6 is connected with the other end of the C3 and a signal output end outputSignal respectively, and the output end outputSignal is connected with an ADC pin of the main controller. The invention adopts a voltage following method to output current. The anti-surge circuit, the isolation circuit and the filter circuit are designed to ensure the safety of the system, and simultaneously, the current signal is converted into a voltage signal which is provided to the main controller for collecting user instructions. The method for collecting the steering analog quantity output by the remote control signal receiver is the same as the method for collecting the straight-going analog quantity output by the remote control signal receiver.

The main controller receives the two paths of analog quantity signals of direct movement and steering sent by the remote control signal receiver, and then converts the analog quantity signals into two paths of digital quantity signals of direct movement and steering through AD acquisition for the motion control of a follow-up forklift synchronization system. Meanwhile, the main controller receives two paths of digital quantity signals of platform lifting and platform descending sent by the remote control signal receiver and is used for subsequent lifting and descending control of the forklift platform.

In order to realize the control of the main controller on the straight servo drive, the steering servo drive, the rotary encoder and the auxiliary control panel, the invention finally adopts RS485 as a communication strategy.

As shown in fig. 4, the TTL to 485 communication circuit diagram of the forklift includes resistors R1, R2 and R7 of 1K Ω, resistors R9 and R10 of 3.3K Ω, resistors R13 and R14 of 22 Ω, resistor R17 of 120 Ω, capacitor C3 of 0.1uf, capacitor C3 of 0.1uf, maximum reverse standby voltage of the transient suppression diodes DR1, DZ1 and DZ2 of 6.5V, thermistor PTC2 and thermistor PTC3 of 0.2A, input MODBUS-RDE connected to the IO pin of the main controller of fig. 2 for controlling the receiving and sending selection of the RS485 circuit, input bus-RX connected to the serial port receiving pin of the main controller of fig. 2, input MODBUS-TX connected to the serial port sending pin of the main controller of fig. 2, resistor rdre connected in series to the rdbus 485 to enable the output port of the bus driver and SP driver to enable the serial port receiving and outputting of the bus-RDE, the other end of a resistor R1 connected in series with an input end MODBUS-RX is simultaneously connected with a receiver output port RO of an SP485 chip, the other end of a resistor R2 connected in series with an input end MODBUS-TX is simultaneously connected with a driver input port DI of the SP485 chip, the A of the SP485 chip is simultaneously connected with R13 and R9, the other end of R9 is simultaneously connected with a power supply port VCC of 5V, C3 and the SP485 chip, the other end of R13 is simultaneously connected with C5, a transient suppression diode DZ1, a transient suppression diode DR1, a resistor R17 and a thermistor PTC2, the other end of a capacitor C3 is simultaneously connected with the other end of C5, the other end of a transient suppression diode DZ1 and GND, the B of the SP485 chip is simultaneously connected with resistors R14 and R10, the other end of R10 is simultaneously connected with a GND port of the SP485 chip, a capacitor C6, a transient suppression diode DZ2 and GND, the other end of the resistor R14 is simultaneously connected with the other end of the capacitor C6 and the transient suppression diode DZ2, The other end of the transient suppression diode DR1, the other end of the resistor R17 and the thermistor PTC3 are connected, the other end of the thermistor PTC2 is connected with MODBUS-B, and the other end of the thermistor PTC3 is connected with MODBUS-A. MODBUS-A is connected with the straight motor servo drive RS485A phase, and MODBUS-B is connected with the straight motor servo drive RS485B phase. The mode of the main controller connecting the steering servo drive, the rotary encoder and the sub-controller through the TTL to 485 communication circuit is the same as the mode of the main controller connecting the straight servo motor drive.

The main controller on the main control panel 31 of the leader forklift is connected with the straight servo drive and the steering servo drive through RS485, and the servo drive respectively controls the straight servo motor and the steering servo motor by changing U, V, W voltage. The main controller is connected with the absolute value rotary encoder and the auxiliary control panel through RS485 respectively, and is connected with the main controller in a straight servo driving mode. The forklift structure of the follower forklift is the same as that of the leader forklift.

As shown in fig. 5, the structure of the dual-forklift synchronization system is schematically illustrated, the synchronization device has a high requirement on time delay of information transmission, and preferably, the CAN bus 30 is selected for control information interaction of the main controllers of the two forklifts.

And the slave controller of the follower forklift obtains the distance between the two forklift heads and the two forklift tails of the laser ranging sensor and the relative height information of the two forklifts through the serial port and sends the information to the master controller of the follower forklift for processing.

Next, a mechanical structure of a topological node designed by the communication topology will be described. As shown in fig. 6, the mechanical structure comprises two parts of an electric pallet fork truck frame 1 and a fork 18, the frame comprises a bearing bridge 7 connected with a vehicle head fixing structure, a fork truck top cover connected above the bearing bridge 7 through a hydraulic cylinder 4, a sun gear 16 rigidly connected below the bearing bridge 7, a steering transmission gear 8 and a rotary encoder transmission gear 9 meshed around the sun gear 16, a transmission gear shaft rigidly connected with a rotary encoder transmission gear shaft and a rotary platform below the sun gear, a driving wheel 14, and transmission lifting connecting rods 17 arranged at two sides of the driving wheel, and a driven wheel 19 is arranged on the fork 18. The control structure of the double-forklift synchronous control device comprises an electric drive device, a lifting hydraulic system, a straight-going servo system, a steering servo system and a sensor structure;

the electric drive device is a power supply fixed in the lower part of the top cover of the forklift, and the power supply supplies power to the whole forklift synchronous control device;

the lifting hydraulic system comprises a hydraulic motor 5, a hydraulic cylinder 4 and an oil tank at the bottom of the hydraulic cylinder; the lifting mode is that the user sends a remote control signal to the hydraulic motor 5, the hydraulic motor 5 fills the hydraulic cylinder 4 with oil in the oil tank through an oil inlet between the hydraulic motor 5 and the hydraulic cylinder 4, and the hydraulic cylinder 4 lifts to lift the forklift platform. The descending mode is that a user sends a remote control signal to open an oil outlet valve at the bottom of the hydraulic cylinder 4, and the forklift platform descends.

The straight servo system comprises a straight servo motor driver 3 and a straight servo motor 15, a user sends straight to a remote controller signal receiver 6 through 433M wireless signals of a remote controller, the remote controller signal receiver 6 converts the wireless signals into straight analog quantity to be transmitted to a main controller 31, and the main controller 31 acquires the speed information intention of the user through AD acquisition. The main controller 31 sends a MOSBUS command to the straight servo driver 3, the straight servo driver 3 controls the straight servo motor 15 to realize the straight movement of the driving wheel 14, and the driven wheel 19 moves along with the movement of the driving wheel 14. Finally, the purpose of controlling the forward and backward movement direction and movement speed of the forklift is achieved.

The steering servo system comprises a steering servo motor driver 2 and a steering servo motor 11, a user sends direct motion and turns to a remote controller signal receiver 6 through 433M wireless signals of a remote controller, the remote controller signal receiver 6 converts the wireless signals into steering analog quantity to be transmitted to a main controller 31, and the main controller 31 acquires angle information intention of the user through AD acquisition. The steering function is that the main controller 31 sends a MOSBUS instruction to the steering servo driver 2, and then the steering servo driver 2 controls the steering servo motor 11, because the friction between the driving wheel 14 and the ground is large and the requirement on speed is not high when the forklift carries heavy objects, the steering servo motor 11 is connected with the planetary reducer 10 to increase the output torque, and the steering movement of the driving wheel 14 is realized through the steering transmission gear 8 meshed with the sun gear 16. Finally, the purpose of controlling the rotation direction and the rotation angle of the forklift is achieved.

The sensor structure comprises a laser ranging sensor 28 and a line groove type laser sensor, wherein the line groove type laser sensor comprises a line type laser generator 29 and a groove type laser receiver 27, the line type laser generator 29 is fixed on a leader forklift and used for emitting line groove type laser, and the groove type laser receiver 27 fixed on a follower forklift generates electric signals of relative positions according to laser received by different hole positions.

The laser ranging sensor 28 mounted on the head of the follower forklift irradiates laser on the inclined plane of the head of the leader forklift, and is used for detecting the head distance between the two forklifts during the synchronous movement of the two forklifts, and when the two forklifts get on or off the goods, because the ranging point of the forklift is the inclined plane, the ranging head can also generate deviation when the height of the two forklifts generates errors, and finally the relative height of the two forklifts is detected. The laser ranging sensor arranged at the tail part of the follower forklift irradiates laser on the tail part of the leader forklift and is used for detecting the tail part distance of the two forklifts during the movement synchronization of the two forklifts.

The mechanical structure also comprises hardware limiting and zero searching functions. The hardware limit function passes through the travel switch 12 and the rotating platform limiting partCollision of vehiclesMake travel switch contact act to realize connection or disconnection controlCircuit arrangement，To achieveThe purpose of mechanical spacing. The zero-searching function is realized by an absolute value rotary encoder 13 with a power-off memory function, so that the zero-searching function is realized automatically when the computer is started.

As shown in fig. 7, the forklift lifting link structure is schematically illustrated, the lifting relay is closed to control the hydraulic motor 5 to charge oil, the piston rod of the oil hydraulic cylinder 4 is lifted up to lift the top of the forklift, the forklift head drives the lifting link 21 at the head to move towards the tail of the forklift, the lifting link 21 at the head makes the bottom link 22 of the forklift move towards the tail of the forklift, and the bottom link 22 of the forklift drives the driven wheel link 23 to rotate clockwise, so that the driven wheel is lifted to the height. When the forklift is in unloading operation, the main controller controls the descending relay to be closed to open the valve of the oil outlet, and the platform descends slowly.

As shown in fig. 8, in the digital quantity acquisition circuit diagram of the forklift truck, the resistor R67 is 5.1K Ω, the resistor R70 is 1K Ω, the resistor R75 is 3K Ω, the capacitors C34 and C36 are 0.1uf, the maximum reverse standby voltage of the transient suppression diode DR6 is 6.5V, the LED12 is an LED green light, the input UpSignal is connected to the uplift digital quantity output of the remote control signal receiver of fig. 2, the other end of the resistor R70 connected in series to the input is connected to the non-inverting input terminal + of the operational amplifier 358 LM and the capacitor C34, the other end of the input UpSignal is connected to the transient suppression diode DR6 and the resistor R67, the other end of the resistor R67 is connected to 3.3V, the other end of the transient suppression diode DR6 is connected to GND, the other end of the capacitor C34 is connected to GND, the positive power supply of the operational amplifier LM is connected to 5V, the other end of the capacitor C36, the other end of the capacitor C36 is connected to GND, the negative power supply of the operational amplifier 358 is connected to GND, the inverting input terminal INA-of the operational amplifier LM358 is connected with the output terminal of the operational amplifier, meanwhile, the output terminal of the operational amplifier is connected with the signal output terminal UP, the other end of the output terminal UP is connected with the LED12, the other end of the LED12 is connected with the resistor R75, and the other end of the resistor R75 is connected with 3.3 v. The output UP is connected to an IO pin of the main controller of fig. 2 for collecting a lifting command sent by the remote control signal receiver. The invention adopts a voltage following method to sample the lifting signal. A rectification circuit and a filter circuit are designed to ensure the safety of the system, and simultaneously, a lifting signal is provided for the main controller to collect a user instruction. The method for collecting the descending signal output by the remote control signal receiver is the same as the method for collecting the ascending signal output by the remote control signal receiver.

As shown in fig. 9, in the relay OUTPUT circuit diagram of the forklift, the resistor R43 is 1.5K Ω, the resistor R45 is 10K Ω, the resistor R47 is 4.7K Ω, the capacitor C38 is 0.1uf, the D9 is a diode, the Q2 is an SS8050 triode, the LED7 is an LED green light, the JK1 is a 24V relay, the rise control information is input through an OUTPUT line, the OUTPUT is connected in series with the resistor R43, the other end of the resistor R43 is simultaneously connected with the bases of C38, R47 and Q2, the other end of C38 is simultaneously connected with the other end of R47, the emitter of Q2 and GND, the collector of Q2 is connected with the armature of JK1, the other end of the armature of the diode D9, the resistor R45 and the relay JK1 is simultaneously connected, the other end of the resistor R45 is connected with the LED7, the UP line is connected with the positive pole of the lifting motor, and the ground line 1 is connected with the lifting motor. The ascending control information processed by the main controller is input into the base of the SS8050 triode through the OUTPUT line on the left side of the relay OUTPUT circuit to obtain input, so that the triode is conducted, the armature of the relay obtains a magnetic field to close the lifting relay switch, the power supply of the lifting motor is connected with the ground during closing, and the lifting motor starts to work. The control method of the descending valve is the same as that of the lifting motor, and the descending relay switch is closed to open the oil outlet valve of the forklift.

The synchronous control method of the double forklifts comprises a basic synchronous movement method, a longitudinal movement deviation adjusting method, a transverse movement deviation adjusting method and an operation height deviation adjusting method.

The basic synchronization movement method according to the present embodiment involves calculation of an ackerman angle during steering movement, and is a schematic diagram of the calculated ackerman angle of a parallel electric pallet truck as shown in fig. 10. In the motion process of the forklift synchronization system, motion estimation of each wheel needs to do circular motion around an instantaneous central point, so that rotation angles of respective driving wheels of a leader forklift and a follower forklift need to be calculated during motion, and the rotation angles meet a certain mathematical relationship, namely an Ackerman angle. The left side of the figure shows a leader forklift wheel model 45 and the right side of the figure shows a follower forklift wheel model 46. The rotating angle of the driving wheel of the leader forklift is zeta, the central point of the driving wheel of the leader forklift and the instantaneous circle center of the steering motion are connected into a first straight line, the central points of the two driven wheels of the leader forklift are connected into a second straight line, and the included angle between the first straight line and the second straight line is zeta 50 through the trigonometric function relation. The corner of the driving wheel of the follower forklift is delta, the central point of the driving wheel of the follower forklift and the instantaneous circle center 51 of the steering motion are connected into a third straight line, the central points of the two driven wheels of the follower forklift are connected into a fourth straight line, and the included angle between the third straight line and the fourth straight line is delta 49 through the trigonometric function relation. K is the center distance 52 of the two main pins of the forklift, and L is the wheelbase 47 of the front and rear wheels of the forklift. The above variables satisfy the following relationships:

cotδ-cotζ＝K/L

the wheelbase L of the front wheels and the rear wheels of the forklift is a constant, the center distance K of the kingpins of the two forklifts can be measured through a laser ranging sensor, the rotating angle zeta of the driving wheel of the leader forklift is given through a user control remote controller, and the rotating angle delta of the driving wheel of the follower forklift can be obtained through calculation. When the driving wheels of the two forklifts advance according to the angle, the two forklifts move around an instantaneous circle center. The method is used in the subsequent basic synchronous motion method and the transverse motion deviation adjusting method.

As shown in fig. 11, the basic synchronous moving method includes the steps of:

firstly, initializing a double-forklift synchronous control device, sending a relevant instruction to a steering servo driver 2 and a straight servo driver 3 by a main controller 31, configuring a steering servo motor 15 into a network operation mode and an absolute motion mode, resetting an incremental encoder and enabling the servo motor; the straight servo motor 11 is configured in a network operation mode, a speed control motion mode and enables the servo motor.

Secondly, the double-forklift main controller 31 reads the position of the absolute value rotary encoder through RS485, calculates whether the forklift driving wheel 14 is aligned or not through comparison, calculates the steering angle offset if the forklift driving wheel 14 is not aligned, and sends an instruction to the steering servo motor 15 to align the driving wheel 14. If the drive wheel 14 has returned to positive, it waits for user input to be obtained.

And thirdly, the remote controller of the user rotates the motion rocker, the remote controller sends out 433M wireless signals, the remote control signal receiving module 6 on the leader forklift receives the wireless signals and converts the wireless signals into analog signals for going straight and turning, and the analog signals are transmitted to the master controller 31 of the leader forklift, and the master controller 31 acquires data required by the user through AD acquisition.

And fourthly, the leader forklift sends the user instruction to the straight-moving and steering servo motors of the leader forklift to drive, and the straight-moving and steering servo motors are controlled to act.

And fifthly, the leader forklift calculates the speed of the straight servo motor of the follower forklift, calculates the ackermann steering angle of the follower forklift, and sends the calculated speed and angle to the follower forklift through the CAN bus 30.

And sixthly, the follower forklift receives the information transmitted by the leader forklift through the CAN bus 30, controls the driving of the straight-going and steering servo motors, and controls the actions of the straight-going and steering servo motors by the driver.

And seventhly, the leader forklift reads the displacement and speed information of the self straight servo driver 3, reads the angle information of the steering servo driver 2, and transmits the related information to the follower forklift through the CAN bus 30. The follower forklift reads the displacement and speed information of the self straight servo driver 3, reads the angle information of the steering servo driver 2, and compares the information to determine whether the adjustment is needed. And if no adjustment is needed, jumping to the third step. And if the adjustment is needed, jumping to the sixth step.

When the basic synchronous movement method is adopted, the two vehicles may not be synchronous longitudinally, so that deviation adjustment is needed.

As shown in fig. 12, the longitudinal movement deviation adjusting method includes the steps of:

firstly, a remote controller of a user rotates a rocker, the remote controller sends out 433M wireless signals, a remote control signal receiving module 6 on the leader forklift receives the wireless signals and converts the wireless signals into analog signals for going straight and turning, and the analog signals are transmitted to a master controller 31 of the leader forklift, and the master controller 31 acquires data required by the user through AD acquisition.

And secondly, the leader forklift sends the user command to a straight servo motor of the leader forklift to drive, and the straight servo motor is controlled to act.

And thirdly, the leader forklift calculates the speed of the straight servo motor moved by the follower forklift, and then sends the speed to the follower forklift through the CAN bus 30.

And fourthly, the follower forklift receives the information transmitted by the leader forklift through the CAN bus 30, sends the information to the straight servo motor for driving, and then controls the straight servo motor to act by the driver.

And fifthly, the leader forklift reads the displacement and speed information of the self straight servo driver 3 and transmits the related information to the follower forklift through the CAN bus 30. The follower forklift reads the displacement and speed information of the self straight servo driver 3 and compares the displacement and speed information to determine whether the adjustment is needed. If no adjustment is needed, jump to the first step. And if the adjustment is needed, jumping to the sixth step.

And sixthly, continuously acquiring the longitudinal offset of the two trucks by using the line slot type laser ranging system of the follower forklift, calculating a longitudinal offset change difference value and accumulating the longitudinal offset by taking the longitudinal offset as input, and calculating the expected real-time speed of the follower forklift by using a PID (proportion integration differentiation) controller determined according to the field condition.

And seventhly, the follower forklift sends the calculated expected speed to a straight servo motor of the follower forklift for driving, and the straight servo motor is controlled to act. And jumping to the fifth step.

As shown in fig. 13, when two forklifts operate synchronously, the laser ranging sensor at the head of the follower forklift starts to measure distance and the laser ranging sensor at the tail of the forklift starts to measure distance, according to the schematic diagram of the large corner lateral deviation of the forklift. Suppose the truck is turning left at the same time (right turn analysis is the same as left turn). When the two vehicles have large corner transverse deviation, the head distance between the two vehicles is increased from an ideal value 35 to an actual value 37, the tail distance between the two vehicles is decreased from an ideal value 36 to an actual value 38, a deflection included angle alpha 39 is formed, and on the basis, the forklift synchronous system is continuously moved to generate large deviation, so that a transverse movement deviation adjusting method is needed to eliminate the deflection included angle alpha.

As shown in fig. 14, the schematic diagram of the forklift with smaller lateral deviation of the turning angle shows that the laser ranging sensor at the head of the following forklift starts to measure the distance and the laser ranging sensor at the tail of the forklift starts to measure the distance when the two forklifts work synchronously. Suppose the truck is turning left at the same time (right turn analysis is the same as left turn). When the two vehicles have small corner transverse deviation, the head distance between the two vehicles is from an ideal value 35 to an actual value 40, the tail distance between the two vehicles is increased from an ideal value 36 to an actual value 42, a deflection included angle beta 42 is formed, and on the basis, the forklift synchronous system is continuously moved to generate large deviation, so that a transverse movement deviation adjusting method is needed to eliminate the deflection included angle beta.

As shown in fig. 15, the method for adjusting the lateral movement deviation of the forklift includes the following steps:

firstly, a remote controller of a user rotates a motion rocker, the remote controller sends out 433M wireless signals, a remote control signal receiving module 6 on the leader forklift receives the wireless signals and converts the wireless signals into analog signals for going straight and turning, and the analog signals are transmitted to a main controller 31 of the leader forklift, and the main controller 31 acquires data required by the user through AD acquisition.

And secondly, the leader forklift sends the user instruction to the straight-moving and steering servo motors of the leader forklift to drive, and controls the straight-moving and steering servo motors to act.

And thirdly, the leader forklift calculates the speed of a straight servo motor moving by the follower forklift, and the ackerman angle of the steering servo motor is sent to the follower forklift through the CAN bus 30.

And fourthly, the follower forklift receives the information transmitted by the leader forklift through the CAN bus 30, sends the information to the direct-moving servo motor and the steering servo motor of the follower forklift for driving, and then controls the direct-moving servo motor and the steering servo motor to act by a driver respectively.

And fifthly, the leader forklift reads the displacement and speed information of the self straight servo driver 3 and transmits the related information to the follower forklift through the CAN bus 30. The follower forklift reads the displacement and speed information of the self straight servo driver 3, reads the angle information of the steering servo driver 2, and compares the information to determine whether the adjustment is needed. If no adjustment is needed, jump to the first step. And if the adjustment is needed, jumping to the sixth step.

And sixthly, continuously acquiring the head distance between the two trucks by the following forklift through the laser ranging sensor at the head part, continuously acquiring the tail distance between the two trucks by the laser ranging sensor at the tail part of the forklift, transmitting the distance information of the two trucks through a CAN (controller area network) bus between the two trucks, calculating the change difference value of the offset angle and accumulating the offset angle by taking the offset angle as input, and calculating the expected real-time angle of the following forklift by utilizing a PID (proportion integration differentiation) controller determined according to the field condition.

And seventhly, the follower forklift sends the calculated speed to a steering servo motor of the follower forklift for driving, and the steering servo motor drives and controls the steering servo motor to act. Then jump to the fifth step.

The basic synchronous motion method, the longitudinal motion deviation adjusting method and the transverse motion deviation adjusting method are combined, so that the double-forklift synchronous system can realize high-precision synchronous motion.

The double-forklift synchronous control device needs to use a synchronous operation function in an actual production scene, so that an operation height deviation adjusting method is further needed to solve the problem that two forklift platforms are not synchronous in synchronous operation.

As shown in fig. 16, which is a schematic diagram of the horizontal height deviation of a parallel type electric pallet fork truck, when two fork trucks operate synchronously, the laser ranging sensor at the head of the follower fork truck emits a beam of line trough laser 43. Since the laser ranging sensor will be shining on the side of the leader truck, which is an inclined surface as shown in fig. 16, the spacing detected by the laser ranging sensor will also shift 44 when the two trucks shift in height. The slope of the inclined plane of the forklift as the leader of the system is fixed, and the height deviation of the two forklifts and the change of the distance between the two forklifts are in a linear relation. In an actual production scene, the two forklifts are relatively static during synchronous operation of the forklift synchronous system, and the head distance between the two forklifts which are relatively static is kept unchanged, so that only the influence of relative height deviation on the head distance of the forklifts exists. The relative height deviation between the two vehicles can be detected by using the laser ranging sensor.

As shown in fig. 17, the method for adjusting the height deviation of the forklift includes the steps of:

firstly, the double-forklift synchronous control device stops moving and starts synchronous operation, and the follower forklift measures the reference relative height of the two forklifts at the horizontal level.

And secondly, the remote controller of the user presses a lifting button and a descending button, the remote controller sends out 433M wireless signals, a remote control signal receiving module 6 on the leader forklift receives the wireless signals and converts the wireless signals into lifting digital signals and descending digital signals, the lifting digital signals are transmitted to the leader forklift main controller 31, and the main controller 31 acquires data required by the user through an IO port.

And thirdly, the leader forklift sends lifting and descending instructions to control the lifting and descending relays to act. And simultaneously, the leader forklift sends lifting and descending instructions to the follower forklift through the CAN bus.

And fourthly, the leader forklift lifts the relay to act the hydraulic motor to lift the forklift platform, and the descending relay acts to open the oil drain brake to descend the forklift platform.

And fifthly, the follower forklift receives the lifting and descending signals sent by the leader forklift, the lifting relay acts on the hydraulic motor to lift the oil-filled forklift platform, and the descending relay acts to enable the oil drain brake to open the forklift platform to descend.

And sixthly, acquiring the relative height between the two trucks once every 0.2s by the follower forklift through the laser ranging sensor at the head of the forklift.

And seventhly, judging the relative height and comparing the relative height with the reference relative height. And if the deviation exists, jumping to the eighth step, and if the deviation does not exist, jumping to the fifth step.

And eighthly, calculating a relative height difference value and an accumulated height difference by using the relative height of the follower forklift, and calculating the action time of the lifting relay and the descending relay of the follower forklift by using a PID (proportion integration differentiation) controller determined according to the field condition.

And step nine, adjusting the height of a follower forklift platform by controlling the action time of the lifting and descending relay, and then jumping to step seven.