阅读说明：本技术 一种货叉式agv卷扬提升系统的松卷判断方法和装置 (Method and device for determining unwinding of pallet fork type AGV hoisting system ) 是由 陈清 黄荣荣 侯典清 朱平 陈静思 许超 于 2020-05-21 设计创作，主要内容包括：一种货叉式AGV卷扬提升系统的松卷判断方法和装置,获取载荷的状态信息和电机的状态信息,根据电机的状态信息和载荷的状态信息并结合预设的阈值判断是否松卷。本发明可以在松卷发生早期做出判断,避免松卷继续发生和恶化,另外,还可以判断出货叉在下降过程中因障碍物阻挡而导致的松卷。(A method and a device for judging the unwinding of a pallet fork type AGV hoisting system are provided, which are used for acquiring the state information of a load and the state information of a motor and judging whether the unwinding is carried out or not according to the state information of the motor and the state information of the load and a preset threshold value. The invention can make a judgment in the early stage of the occurrence of the coil loosening, avoid the continuous occurrence and the deterioration of the coil loosening and can judge the coil loosening caused by the obstruction of the goods fork in the descending process.)

1. A coil loosening judgment method of a fork type AGV hoisting system is characterized by comprising the following steps: and acquiring the state information of the load and the state information of the motor, and judging whether the coil is unwound or not according to the state information of the motor and the state information of the load and combining a preset threshold value.

2. The method of claim 1, wherein said method comprises: the state information of the motor is the rotating speed of the motor, and the state information of the load is the height of the load; and in a certain time window, calculating a first lifting speed according to the height of the load, calculating a second lifting speed according to the rotating speed of the motor, and if the difference value between the second lifting speed and the first lifting speed is greater than a preset threshold value, winding and unwinding.

3. The method of claim 2, wherein said method comprises: the first lifting speed calculation method is as follows: in a time window, calculating the lifting speed of each sampling interval according to the height of the load, and filtering to eliminate error values with overlarge deviation; and calculating an average value of the plurality of filtered lifting speeds to obtain a first lifting speed.

4. The method of claim 2, wherein said method comprises: the second lifting speed calculation method is as follows: in the time window, filtering is firstly carried out on the rotating speed of the motor to eliminate error values with overlarge deviation, then the lifting speed of each sampling interval is calculated according to the rotating speed of the motor, and an average value is calculated for a plurality of lifting speeds to obtain a second lifting speed.

5. The method of claim 1, wherein said method comprises: the state information of the motor is the steering direction of the motor, the state information of the load is the height of the load, and if the motor rotates towards the direction of driving the load to descend within a certain time interval and the height difference of the load is smaller than a preset threshold value, the motor is hoisted and unwound.

6. The method of claim 1, wherein said method comprises: the state information of the motor is the steering of the motor, and the state information of the load is the actual load; and if the motor rotates towards the descending direction in the current state and the actual load is smaller than the preset threshold value, winding and unwinding.

7. The method of claim 6, wherein said method comprises: and the actual load is related to the current of the motor, and if the motor rotates towards the descending direction in the current state and the current of the motor is smaller than a preset threshold value, the motor is hoisted and unwound.

8. The utility model provides a device is judged to fork formula AGV hoist lifting system's pine book which characterized in that: the method for determining the unwinding of a fork AGV hoist lift system as claimed in any one of claims 1 to 7, comprising

A first detection unit which acquires the state information of the load;

the second detection unit is used for acquiring the state information of the motor;

and the control unit processes the load state information and the motor state information and judges whether the coil is unwound or not by combining a preset threshold value.

9. The system of claim 8 wherein said system further comprises: the state information of the load comprises the height of the load or the actual load, and the first detection unit is a height sensor or a current sensor.

10. The system of claim 8 wherein said system further comprises: the state information of the motor comprises the rotating speed of the motor or the rotating direction of the motor, and the second detection unit is a motor rotating speed sensor or a motor encoder.

Technical Field

The invention relates to the field of forklifts, in particular to a method and a device for judging unwinding of a fork type AGV hoisting system.

Background

A hoisting and lifting system of a fork type AGV realizes the lifting motion of a fork by using a hoisting mechanism. One end of a common hoisting mechanism such as a steel wire rope, a flat belt and the like is fixed on the winding drum, and winding and unwinding are realized along with the rotation of the winding drum; the other end is fixed on the fork carriage. The control unit of AGV drives the hoist motor to rotate, drives the reel rotation to realize the elevating movement of fork.

Currently, hoisting systems that employ hoisting mechanisms can suffer from unwinding problems. The reasons for this phenomenon are generally: firstly, when the pallet fork is lowered to the lowest position, the hoisting motor continues to rotate; and secondly, the fork can not descend normally when being blocked by an obstacle in the descending process. At this time, the steel wire rope, the flat belt and the like between the pallet fork and the winding drum lose due tension and are loosened, and further, the steel wire rope, the flat belt and the like reserved on the winding drum are loosened, so that potential safety hazards are generated.

The common judgment method is to install a proximity switch on a winding drum, and the detection position of the proximity switch is generally the critical position of the minimum number of reserved turns required by a steel wire rope, a flat belt and the like. And whether the reserved steel wire rope, the flat belt and the like on the winding drum are discharged or not is judged through the feedback signal of the proximity switch, so that the judgment of unwinding is realized. This method can determine the unwinding due to the first cause, but cannot make a timely determination of the second cause.

Disclosure of Invention

The invention mainly aims to overcome the defects in the prior art and provides a method and a device for judging the unwinding of a fork type AGV hoisting system, wherein the method and the device are more accurate in judgment and can effectively avoid the continuous occurrence and deterioration of the unwinding.

The invention adopts the following technical scheme:

a coil loosening judgment method of a fork type AGV hoisting system is characterized by comprising the following steps: and acquiring the state information of the load and the state information of the motor, and judging whether the coil is unwound or not according to the state information of the motor and the state information of the load and combining a preset threshold value.

Preferably, the state information of the motor is the rotating speed of the motor, and the state information of the load is the height of the load; and in a certain time window, calculating a first lifting speed according to the height of the load, calculating a second lifting speed according to the rotating speed of the motor, and if the difference value between the second lifting speed and the first lifting speed is greater than a preset threshold value, winding and unwinding.

Preferably, the first lifting speed calculation method includes: in a time window, calculating the lifting speed of each sampling interval according to the height of the load, and filtering to eliminate error values with overlarge deviation; and calculating an average value of the plurality of filtered lifting speeds to obtain a first lifting speed.

Preferably, the second lifting speed calculation method includes: in the time window, filtering is firstly carried out on the rotating speed of the motor to eliminate error values with overlarge deviation, then the lifting speed of each sampling interval is calculated according to the rotating speed of the motor, and an average value is calculated for a plurality of lifting speeds to obtain a second lifting speed.

Preferably, the state information of the motor is the steering direction of the motor, the state information of the load is the height of the load, and if the motor rotates towards the direction driving the load to descend within a certain time interval and the height difference of the load is smaller than a preset threshold value, the winding and unwinding are performed.

Preferably, the state information of the motor is the steering of the motor, and the state information of the load is the actual load; and if the motor rotates towards the descending direction in the current state and the actual load is smaller than the preset threshold value, winding and unwinding.

Preferably, the actual load is related to a current of the motor, and if the motor rotates in a descending direction in the current state and the current of the motor is smaller than a preset threshold, the winding and unwinding are performed.

The utility model provides a device is judged to fork formula AGV hoist lifting system's pine book which characterized in that: the method for judging the unwinding of the fork type AGV hoisting system comprises the following steps

A first detection unit which acquires the state information of the load;

the second detection unit is used for acquiring the state information of the motor;

and the control unit processes the load state information and the motor state information and judges whether the coil is unwound or not by combining a preset threshold value.

The state information of the load comprises the height of the load or the actual load, and the first detection unit is a height sensor or a current sensor.

The state information of the motor comprises the rotating speed of the motor or the rotating direction of the motor, and the second detection unit is a motor rotating speed sensor or a motor encoder.

As can be seen from the above description of the present invention, compared with the prior art, the present invention has the following advantages:

1. according to the method and the device, the state information of the load and the state information of the motor are obtained, whether the coil is loosened is judged according to the state information of the motor and the state information of the load and a preset threshold value, the judgment can be made in the early stage of the coil loosening, and the judgment is not needed to be made after the reserved number of turns is reduced to the critical value. Avoid the lap loosening to continue taking place and worsening, in addition, can also judge the lap loosening that the fork leads to because of the barrier stops at the decline in-process to improve AGV automation mechanized operation's security, thereby judge in time that the lap loosening takes place to reduce the downtime that the lap loosening arouses, improved efficiency.

2. According to the method and the device, the state information of the load comprises the height of the load or the actual load, the state information of the motor comprises the rotating speed of the motor or the rotating direction of the motor, the unwinding is judged through specific information combination, the judgment modes are various, the principle is simple, and the realization is easy.

3. According to the device, the first detection unit is the height sensor or the current sensor, the second detection unit is the motor rotating speed sensor or the motor encoder, the structure of the original lifting system is slightly changed, the preset threshold value can be set according to requirements, and the device is convenient to popularize.

Drawings

FIG. 1 is a main flow chart of the present invention;

FIG. 2 is a flow chart of an embodiment of the present invention;

FIG. 3 is a schematic view of a stay wire encoder installation;

FIG. 4 is a schematic view of a laser rangefinder installation;

FIG. 5 is a first lift velocity calculation flow chart;

FIG. 6 is a second lift velocity calculation flow chart;

FIG. 7 is a flowchart of an embodiment;

FIG. 8 is an embodiment flowchart.

The invention is described in further detail below with reference to the figures and specific examples.

Detailed Description

The invention is further described below by means of specific embodiments.

Referring to fig. 1, a method for judging unwinding of a fork type AGV hoisting system acquires state information of a motor and state information of a load, and judges whether to unwind according to the state information of the motor and the state information of the load in combination with a preset threshold.

Correspondingly, the invention provides an unwinding judgment device of a fork type AGV hoisting system, which comprises

A first detection unit for acquiring state information of the load; the second detection unit is used for acquiring the state information of the motor; and the control unit is used for processing according to the state information of the motor and the state information of the load and judging whether the coil is unwound or not by combining a preset threshold value.

In the present invention, the state information of the load includes a height of the load or an actual load, the first detecting unit is a height sensor or a current sensor, and the actual load is related to the motor torque. The state information of the motor comprises the rotating speed of the motor or the rotating direction of the motor, and the second detection unit is a motor rotating speed sensor or a motor encoder and the like. The invention can adopt different methods to judge the roll loosening condition according to different information.

Example one

Referring to fig. 2, a method for judging unwinding of a fork type AGV hoisting system acquires state information of a motor and state information of a load, and judges whether to unwind according to the state information of the motor and the state information of the load in combination with a preset threshold. The state information of the motor is the rotating speed of the motor, and the state information of the load is the height of the load; and in a certain time window, calculating a first lifting speed according to the height of the load, calculating a second lifting speed according to the rotating speed of the motor, if the difference value between the second lifting speed and the first lifting speed is greater than a preset threshold value, winding and unwinding, otherwise, the winding is normal.

Further, referring to fig. 5, the first lifting speed calculation method is as follows: calculating the lifting speed of each sampling interval in the time window, and filtering to eliminate error values with overlarge deviation; and calculating an average value of the plurality of filtered lifting speeds to obtain a first lifting speed. Wherein, the current time t is obtained₁，t₂,...t_nCorresponding lifting height H of load₁,H₂,...H_nCalculating the lifting speed in all sampling intervals and recording as v₁，v₂，v₃...v_n-1The calculation formula is as follows:wherein i is 1, 2.

The total duration of t1 to tn is a time window, and the time difference between every two adjacent sampling moments in t1 to tn is a sampling interval. The selection of the time window is combined with the requirement of loosening judgment frequency. Reducing the time window can improve the frequency of the roll loosening judgment, but also increases the operation burden of the system control unit. In this embodiment, the time window may be 500-1000 ms.

The selection of the sampling interval should combine the real-time requirement of data, the sampling frequency of the sensor and the working condition characteristics of the lifting mechanism. The sampling interval is reduced, the real-time performance of data is improved, the sampling frequency of the sensor is increased, and meanwhile, the acquired data are prone to being inaccurate due to the influence of instantaneous impact of lifting motion. In this embodiment, the sampling interval may be selected from 50 to 100 ms.

Referring to fig. 6, the second lifting speed calculation method is as follows: in the time window, the lifting of each sampling interval is calculated according to the rotating speed of the motorSpeed, filtering and eliminating error values with overlarge deviation; and calculating an average value of the plurality of filtered lifting speeds to obtain a first lifting speed. Specifically, at t₁,t₂,...t_nAt the moment, the rotating speed N of the motor is obtained₁，N₂，...N_n. To motor rotating speed N₁，N₂，...N_nAnd filtering to eliminate error values with overlarge deviation. And respectively calculating corresponding lifting speeds of the plurality of filtered rotating speed values, and calculating an average value of the obtained lifting speeds to obtain a second lifting speed.

In the hoisting and lifting system, if parameters such as the rotating speed of a motor, the speed ratio of a speed reducer, the hoisting radius and the like are known, the hoisting and lifting speed is calculated by the following formula:wherein N is the motor rotating speed and the unit r/min; r is the hoisting radius in mm; i is the speed reducer ratio; v in mm/s.

The preset threshold value a is a critical value for determining whether or not unwinding occurs, and is set in advance and stored in a control unit of the system. If the absolute value of the difference value between the second lifting speed and the first lifting speed is larger than A, the lifting speed corresponding to the rotating speed of the motor is larger than the actual lifting speed of the pallet fork within the same time, and the speed difference exceeds the critical value of the occurrence of unrolling. In this case, if the winding is about to be unwound, the unwinding alarm can be performed, otherwise, the operation is finished.

The embodiment also provides a device for judging the unwinding of the fork type AGV hoisting system, which adopts the judging method, wherein the first detection unit is a height sensor, and the second detection unit is a motor speed sensor. The installation position of the height sensor can be set according to the requirement, and the installation position comprises the bottom, the top, the side and the like of the frame without limitation.

Referring to fig. 3, 4, the height sensor may be a pull-wire encoder. The stay-supported encoder body is fixed at the bottom of a forklift frame, and the tail end of a encoder rope is fixed with the lifting mechanism. When the lifting mechanism acts, the wire rope is pulled out or retracted, the encoder shaft is driven to rotate, and an electric signal is generated. As shown in fig. 3, 2, the height sensor may also be a laser rangefinder. The laser emitter and the receiver are fixed at the bottom of the frame, and the reflecting plate is fixed on the lifting mechanism. The laser beam emitted by the laser emitter irradiates the reflecting plate and is reflected, and then is received by the laser receiver, and the height information can be obtained by calculating the flight time of the laser.

In this embodiment, the selection of the preset threshold a should be combined with the requirements of the measurement accuracy and error of the sensor and the accuracy of the determination of the unwinding. The smaller A is, the higher the unwinding judgment precision is, but the requirement of the measurement precision of the sensor is also improved, and the misjudgment risk is increased. In the embodiment, A can be selected from 50-100 mm/s.

Example two

Referring to fig. 7, a method for judging unwinding of a fork type AGV hoisting system acquires state information of a motor and state information of a load, and judges whether to unwind according to the state information of the motor and the state information of the load in combination with a preset threshold. The state information of the motor is the steering direction of the motor, the state information of the load is the height of the load, and if the motor rotates towards the direction of driving the load to descend within a certain time interval and the height difference of the load is smaller than a preset threshold value, the motor is hoisted and unwound.

In this embodiment, the lifting heights H1 and H2 of the load are taken at times t1 and t2, respectively. the time interval between t1 and t2 can be selected according to the actual lifting speed, and in the embodiment, the time interval between t1 and t2 can be selected from 1-3 s. Whether the motor steering is turned in the ascending or descending direction in the period t1 to t2 is judged according to the acquired motor encoder signal. And if the motor rotates towards the descending direction and the difference value between H1 and H2 is smaller than a threshold value A, judging that the coil is loosened, giving an alarm for the coil loosening, and if not, ending the alarm.

The embodiment also provides a device for judging the unwinding of the fork type AGV hoisting system, which adopts the judging method, wherein the adopted first detection unit is a height sensor, and the second detection unit is a motor encoder.

The preset threshold value a is a critical value for determining whether the lift height changes, and is set in advance and stored in the system control unit. If H1-H2 is less than a, it means that the lift mechanism of the forklift does not descend during the time period t1 to t2, but the motor still rotates in the descending direction, in which case the winch will unwind.

In this embodiment, the selection of the preset threshold a should be combined with the requirements of the lifting speed, the time intervals t1 and t2, and the judgment precision. In this embodiment, A may be 0.5-1 mm.

EXAMPLE III

Referring to fig. 8, a method for judging unwinding of a fork type AGV hoisting system acquires state information of a motor and state information of a load, and judges whether to unwind according to the state information of the motor and the state information of the load in combination with a preset threshold. The state information of the motor is the steering of the motor, and the state information of the load is the actual load; and if the motor rotates towards the descending direction in the current state and the actual load is smaller than the preset threshold value, winding and unwinding.

The actual load is related to the torque of the motor, the torque of the motor is related to the current of the motor, when the current of the motor is smaller than the rated current, the current of the motor is reduced along with the reduction of the output torque of the motor, and the actual load is small. The current load situation can thus be determined by the current of the motor. And if the motor rotates towards the descending direction in the current state and the current I of the motor is smaller than the preset threshold value A, winding and unwinding, and performing unwinding alarm.

The embodiment also provides a device for judging the unwinding of the fork type AGV hoisting system, the judgment method is adopted, the adopted first detection unit is a current sensor, and the adopted second detection unit is a motor encoder. The control unit respectively obtains the motor current and the motor steering from the first detection unit and the second detection unit, judges the motor torque through the motor current and further judges whether the coil is loosened.

The preset threshold a is a current critical value for determining whether the motor torque is too small, and is set in advance and stored in the control unit. The preset threshold value a represents the minimum lifting load of the lifting mechanism (typically the lifting mechanism's own weight). When the lifting mechanism meets an obstacle and is loosened in the descending process, the torque of the lifting mechanism and the load acting on the motor is counteracted by the obstacle, so that the output torque of the motor is smaller than the torque required by the minimum lifting load.

The above description is only an embodiment of the present invention, but the design concept of the present invention is not limited thereto, and any insubstantial modifications made by using the design concept should fall within the scope of infringing the present invention.