阅读说明：本技术 一种适用于便携式转台的控制方法 (Control method suitable for portable turntable ) 是由 朱美俊 王超 苟义龙 米乾宝 顾鹏 郭佳赟 樊峰宇 赵哲 于 2020-06-23 设计创作，主要内容包括：本发明公开了一种适用于便携式转台的控制方法,该方法通过电机的正反转带动高精度编码器旋转,获取、分析电机端的霍尔传感器和高精度编码器数据的方式来测量传动死区。通过高精度编码器结合减速比来实时计算电机转子位置,再利用霍尔传感器精确校正电机转子位置,判断电机是否处于传动死区,以在控制中实现死区补偿,该控制方法具有定位工作模式和速度工作模式。在定位控制模式下,本发明在系统精度允许范围内,采用变稳定点的控制算法,实现快速、平稳、精确的定位功能。在速度控制模式下,本发明利用高减速比系统的自身鲁棒性,电机速度环采取差角控制算法,保证系统无论在高速和低速下都能的平稳运行。(The invention discloses a control method suitable for a portable turntable, which is used for measuring a transmission dead zone by driving a high-precision encoder to rotate through positive and negative rotation of a motor and acquiring and analyzing data of a Hall sensor and the high-precision encoder at the end of the motor. The position of the motor rotor is calculated in real time by combining a high-precision encoder with a speed reduction ratio, the position of the motor rotor is accurately corrected by using a Hall sensor, whether the motor is in a transmission dead zone or not is judged, and dead zone compensation is realized in control. In the positioning control mode, the invention adopts a control algorithm of a variable stable point within the allowable range of system precision to realize the rapid, stable and accurate positioning function. In the speed control mode, the invention utilizes the self robustness of the high reduction ratio system, and the motor speed ring adopts a differential angle control algorithm to ensure that the system can stably run no matter at high speed or low speed.)

1. A control method suitable for a portable turntable is characterized in that: install high accuracy encoder on the carousel of portable revolving stage, install hall sensor on the motor output shaft of portable revolving stage, its concrete control step is:

step 1: transmission dead band detection

Step 1.1: the motor drives the turntable to rotate, and when signals of the motor Hall sensor and the high-precision encoder change, the signal position of the Hall sensor at the moment is recorded as H1, and the signal position of the high-precision encoder at the moment is recorded as P1;

step 1.2: then the motor reversely drives the turntable to rotate, when signals of the Hall sensor and the high-precision encoder of the motor change again, the signal position of the Hall sensor at the moment is recorded as H2, and the signal position of the high-precision encoder at the moment is recorded as P2;

step 1.3: and (3) calculating a transmission dead zone S, wherein the specific calculation formula is as follows: (ii) S ═ P2-P1-H2+ H1-

Step 2: acquiring the position of a motor rotor at the current moment in real time;

step 2.1: obtaining the position P of the high-precision encoder at the current moment and combining the reduction ratio K₁Calculating the position of the rotor of the motor at the current moment

Step 2.2: when the Hall signal at the motor end changes, the actual position of the motor obtained by the Hall signal is calculatedAnd simultaneously calculating the position of the rotor of the motor at the moment according to the mode of the step 2.1

step 2.3: calculating the corrected rotor position theta of the motor at the current moment_rotThe concrete calculation formula is as follows:

and step 3: inputting a working mode;

when the input working mode is the speed working mode, executing the step 4; when the input working mode is the positioning working mode, executing the step 5;

and 4, step 4: the motor rotor is controlled in a speed working mode, so that the turntable is controlled;

and 5: and controlling the motor rotor in a positioning working mode so as to realize the control of the rotary table.

2. The control method for a portable turntable according to claim 1, wherein: the step 4 is carried out by adopting a speed ring difference angle control mode, and the specific steps are as follows:

step 4.1: establishing a rotation vector voltage amplitude control module; the rotation vector voltage amplitude control module comprises a comparator, a proportional-integral controller, a selector and a difference angle calculator;

step 4.2: acquiring an actual angle difference;

step 4.2.1: according to the current angular position theta of the motor rotor_rotCalculating the current electrical angle theta of the motor rotor_elThe specific calculation formula is as follows: theta_el＝θ_rot×N_pp；

N_ppThe number of pole pairs of the motor is;

step 4.2.2: according to given speed v and phase angle theta of rotating vector voltage_votGenerating the position to be reached by the rotor of the motor at the next moment

Step 4.2.3: the electric angle of the motor rotor and the rotating vector voltage phase angle are subjected to difference by a difference angle calculator to obtain an absolute value to obtain an actual angle difference theta_dtAnd feeds it back to the comparator;

actual angular difference θ_dtThe specific calculation formula of (A) is as follows: theta_dt＝|θ_el-θ_vot|；

Step 4.3: inputting the set desired angular difference theta into the comparator_refAnd calculating the actual angular difference theta_dtTaking the difference as a feedback value of the comparator, and outputting a difference result to the proportional-integral controller to obtain the required magnitude of the voltage amplitude of the rotation vector; theta_refThe value range of (0 degrees, 90 degrees);

step 4.4: the selector judges whether the motor is in a dead zone or not, and if the motor is in the dead zone, the motor rotor is controlled to rotate according to the fixed voltage output amplitude; and if the motor rotor is not in the dead zone, controlling the motor rotor according to the amplitude of the voltage of the rotating vector acquired in the step 4.3, so as to realize the control of the rotary table.

3. The control method for a portable turntable according to claim 1, wherein: the step 4 is carried out by adopting a positioning control mode of a variable stabilization point, and the specific steps are as follows:

step 5.1: setting the final positioning target point O and the allowable error range of the final positioning target point O as [ -d1, + d1 ];

step 5.2: judging the current position of the motor rotor, and adjusting the current position to a final target point O;

the first condition is as follows: if the current motor rotor position is less than-d 1, setting the temporary control target to be-d 1 position, so that the motor rotor rotates towards-d 1 position, and starting to execute the third condition when the motor rotor position enters the interval of [ -d1, + d1 ];

case two: if the current motor rotor position is greater than + d1, setting the temporary control target to be + d1 position, so that the motor rotor rotates towards-d 1 position, and starting to execute the third condition when the motor rotor position enters the range of [ -d1, + d1 ];

case three: if the current motor rotor position is in the range of [ -d1, + d1], if the current motor rotor moves towards the position of + d1, the temporary control target is adjusted to be the position of-d 1, if the current motor rotor moves towards the position of-d 1, the temporary control target is adjusted to be the position of + d1, and after repeated exchange of the temporary control target for multiple times, the motor rotor position finally reaches the final target point O, so that the control of the rotary table is realized.

Technical Field

The invention belongs to the rotary table control technology, and particularly relates to a control method suitable for a portable rotary table.

Background

The rotary table is commonly used in the surveying and mapping equipment, and the surveying and mapping equipment is driven to realize high-precision stable surveying and mapping work. The accuracy of the control of the rotary table is one of the most central problems considered by the designer of the rotary table, and due to the existence of the multi-stage speed reducer, the output end of the motor and the output end of the rotary table have a large dead zone, which has a large negative influence on the rapidity, the stability and the control accuracy of the control of the rotary table, and the existing rotary table has more control modes, such as:

chinese patent, publication No. CN110544828A, entitled "Dual-Motor control System and method for antenna turntable of Special Equipment", the technical scheme adopted by the patent is as follows: the mode that two motors drive the same output shaft enables the output shaft to be always in contact with the driving shaft, and the influence of a dead zone on control precision is eliminated.

The Chinese patent, publication No. CN206478215U, entitled "a turntable with double-transmission chain anti-backlash device", adopts the technical scheme as follows: the mode that one motor drives two identical speed reducers to drive the same output shaft enables the output shaft to be always in contact with the driving shaft, and the influence of a dead zone on control precision is eliminated.

With the continuous progress of science and technology, some surveying and mapping work needs to be carried out in the field, so that a portable turntable needs to be designed, and the portable turntable generally needs to have the characteristics of small size, light weight, strong load capacity, large output torque, high precision, low cost and the like.

Although the technical solutions disclosed in the above two patents all eliminate the influence of the dead zone on the control precision of the turntable, thereby obtaining a good control effect, the control modes of the above two technical solutions are restricted by the size, weight, power consumption and cost of the portable turntable, so that the above modes are hardly applicable to the portable turntable, and the conventional control modes have defects in both the positioning working mode and the speed working mode:

1. in a positioning working mode, due to the existence of a transmission dead zone and the fact that the static friction of a system is far larger than the dynamic friction characteristic, the positioning process is difficult to adjust quickly and stably in the existing method.

2. In a speed control mode, because a transmission dead zone exists and the static friction of a system is far larger than the dynamic friction, the traditional method can enable the motor to output large torque by applying a voltage vector perpendicular to a motor rotor and controlling the motor rotor to rotate by adjusting the size, but the stable running of the system at low speed is difficult to ensure, so that the friction damping is increased and the power consumption of the system is increased.

Disclosure of Invention

In order to solve the problem that the existing control mode of the rotary table is difficult to be suitable for the portable rotary table, the invention provides the control method suitable for the portable rotary table, and the control method can eliminate the influence of a dead zone on the control precision, thereby realizing the high-precision and quick positioning control of the portable rotary table and the speed control with wide speed setting range and small speed fluctuation.

The basic design principle of the invention is as follows:

in order to realize good motor magnetic field directional control, a transmission dead zone and a motor rotor real-time position need to be obtained. The high-precision encoder of the output shaft is driven to rotate through the positive and negative rotation of the motor, and the transmission dead zone is measured in a mode of acquiring and analyzing data of the Hall sensor and the high-precision encoder at the motor end. The position of the motor rotor is calculated in real time by combining a high-precision encoder with a speed reduction ratio, and the position of the motor rotor is accurately determined in real time by accurately correcting the position of the motor rotor by using a Hall sensor. The control method comprises the steps of judging whether a motor is in a transmission dead zone or not by combining data of a Hall sensor and an output shaft high-precision encoder with a reduction ratio so as to realize dead zone compensation in control, wherein the control method comprises a positioning working mode and a speed working mode.

In the positioning control mode, the invention adopts a control algorithm of a variable stable point within the allowable range of system precision to realize the rapid, stable and accurate positioning function.

In the speed control mode, the invention utilizes the self robustness of the high reduction ratio system, and the motor speed ring adopts a differential angle control algorithm to ensure that the system can stably run no matter at high speed or low speed.

The specific technical scheme of the invention is as follows:

the invention provides a control method suitable for a portable turntable, wherein a high-precision encoder is arranged on a turntable of the portable turntable, a Hall sensor is arranged on a motor output shaft of the portable turntable, and the control method comprises the following specific steps:

step 1: transmission dead band detection

Step 1.1: the motor drives the turntable to rotate, and when signals of the Hall sensor and the high-precision encoder change, the signal position of the Hall sensor at the moment is recorded as H1, and the signal position of the high-precision encoder at the moment is recorded as P1;

step 1.2: then the motor reversely drives the turntable to rotate, when signals of the Hall sensor and the high-precision encoder of the motor change again, the signal position of the Hall sensor at the moment is recorded as H2, and the signal position of the high-precision encoder at the moment is recorded as P2;

step 1.3: and (3) calculating a transmission dead zone S, wherein the specific calculation formula is as follows: s ═ P2-P1-H2+ H1 |;

step 2: acquiring the position of a motor rotor at the current moment in real time;

step 2.1: obtaining the position P of the high-precision encoder at the current moment and combining the reduction ratio K₁Calculating the position of the rotor of the motor at the current moment

Step 2.2: when the Hall signal at the motor end changes, the actual position of the motor obtained by the Hall signal is calculatedAnd at the same timeThe position of the rotor of the motor at the moment is calculated according to the mode of the step 2.1

And recording;

step 2.3: calculating the corrected rotor position theta of the motor at the current moment_rotThe concrete calculation formula is as follows:

and step 3: inputting a working mode;

when the input working mode is the speed working mode, executing the step 4; when the input working mode is the positioning working mode, executing the step 5;

and 4, step 4: the motor rotor is controlled in a speed working mode, so that the turntable is controlled;

and 5: and controlling the motor rotor in a positioning working mode so as to realize the control of the rotary table.

Further, the step 4 is performed by adopting a speed loop difference angle control mode, and the specific implementation process is as follows:

step 4.1: establishing a rotation vector voltage amplitude control module; the rotation vector voltage amplitude control module comprises a comparator, a proportional-integral controller, a selector and a difference angle calculator;

step 4.2: acquiring an actual angle difference;

step 4.2.1: according to the current angular position theta of the motor rotor_rotCalculating the current electrical angle theta of the motor rotor_elThe specific calculation formula is as follows: theta_el＝θ_rot×N_pp；

N_ppThe number of pole pairs of the motor is;

step 4.2.2: according to given speed v and phase angle theta of rotating vector voltage_votGenerating the position to be reached by the rotor of the motor at the next moment

Step 4.2.3: the electric angle of the motor rotor and the rotating vector voltage phase angle are subjected to difference by a difference angle calculator to obtain an absolute value to obtain an actual angle difference theta_dtAnd feeds it back to the comparator;

actual angular difference θ_dtThe specific calculation formula of (A) is as follows: theta_dt＝|θ_el-θ_vot|；

Step 4.3: inputting the set desired angular difference theta into the comparator_refAnd calculating the actual angular difference theta_dtTaking the difference as a feedback value of the comparator, and outputting a difference result to the proportional-integral controller to obtain the required magnitude of the voltage amplitude of the rotation vector; theta_refThe value range of (0 degrees, 90 degrees);

step 4.4: the selector judges whether the motor is in a dead zone or not, and if the motor is in the dead zone, the motor rotor is controlled to rotate according to the fixed voltage output amplitude; if the motor rotor is not in the dead zone, the motor rotor is controlled according to the amplitude of the rotating vector voltage obtained in the step 4.3, so that the turntable is controlled; the value range of the fixed voltage output amplitude is manually set according to specific working conditions, and specific reference standards are rated voltage of the motor, the friction condition of an object and the like.

Further, the step 5 is performed by using a positioning control mode of a variable stabilization point, and the specific process is as follows:

step 5.1: setting the final positioning target point O and the allowable error range of the final positioning target point O as [ -d1, + d1 ];

step 5.2: judging the current position of the motor rotor, and adjusting the current position to a final target point O;

the first condition is as follows: if the current motor rotor position is less than-d 1, setting the temporary control target to be-d 1 position, so that the motor rotor rotates towards-d 1 position, and starting to execute the third condition when the motor rotor position enters the interval of [ -d1, + d1 ];

case two: if the current motor rotor position is greater than + d1, setting the temporary control target to be + d1 position, so that the motor rotor rotates towards-d 1 position, and starting to execute the third condition when the motor rotor position enters the range of [ -d1, + d1 ];

case three: if the current motor rotor position is in the range of [ -d1, + d1], if the current motor rotor moves towards the position of + d1, the temporary control target is adjusted to be the position of-d 1, if the current motor rotor moves towards the position of-d 1, the temporary control target is adjusted to be the position of + d1, and after repeated exchange of the temporary control target for multiple times, the motor rotor position finally reaches the final target point O, so that the control of the rotary table is realized.

The invention has the beneficial effects that:

1. the method of the invention can realize the accurate control of the motor by the positioning correction of the motor shaft by the Hall sensor because the Hall sensor is arranged at the end of the motor shaft and the high-precision encoder is arranged on the turntable, and can accurately detect the dead zone of the system transmission and the position of the motor by the data analysis of the positive and negative rotation, thereby realizing the directional control of the magnetic field. The scheme can meet the requirements of the system on high precision and low cost, and has good control performance.

2. The method of the invention provides a speed difference angle control algorithm when carrying out speed loop control on the output shaft of the transmission mechanism with high reduction ratio, the method adopts a mode of combining open-loop control and closed-loop control, and the open-loop part comprises the following steps: the phase angle of the rotating vector voltage (current) is determined by a given speed, and the open-loop control utilizes the robustness of a high reduction ratio system to external disturbance and the stress characteristic of the motor (the motor rotor is always pulled to a position parallel to the vector voltage), so that the motor can stably run in a speed mode; a closed loop part: the motor is ensured to stably rotate along with the vector voltage (current) all the time in a mode of controlling the phase angle of the rotating vector voltage (current) by controlling the amplitude value of the rotating vector voltage (current) and the position difference angle of the motor rotor. The control mode enables the system to have the characteristics of good stability, robustness and low power consumption.

3. The method of the invention provides a variable stable point control algorithm for the control precision range.

1) When the controlled object is out of the allowable error, the system takes the position closest to the allowable error range as the control target position, and has higher quick performance compared with the traditional mode of changing the gain (the controller gain is different at different speeds);

2) when the system enters the allowable error range, the system quickly calls back to quickly stop the controlled object so as to prevent overshoot, and the method is equivalent to increasing the system damping in the allowable error range of the system to quickly stop the system in the allowable error range;

3) since the force for returning to the target position is greater than the force for adjusting in the opposite direction within the allowable error range, the system gradually adjusts to the target position within the allowable error range until the error is eliminated.

The method is extremely effective in dead zone control, and can ensure control precision and rapidity and stability of a controlled object.

Drawings

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

FIG. 2 is a schematic diagram of the speed difference angle control principle;

FIG. 3 is a schematic diagram of a rotating vector voltage magnitude control module.

FIG. 4 is a schematic diagram of a variable stable point control principle;

FIG. 5 is a flow chart of a variable stability point control algorithm.

Detailed Description

To make the objects, advantages and features of the present invention more apparent, a control method for a portable turntable according to the present invention will be described in detail with reference to the accompanying drawings and specific embodiments. The advantages and features of the present invention will become more apparent from the following description. It should be noted that: the drawings are in simplified form and are not to precise scale, the intention being solely for the convenience and clarity of illustrating embodiments of the invention; second, the structures shown in the drawings are often part of actual structures.