TWI460564B - Controlling method using pid controller, controlling device thereof and robot with same - Google Patents

Description

PID controller control method and control device and robot

The present invention relates to a control method and a control device, and a robot having the same, and more particularly to a control method and control device using a PID controller and a robot having the same.

In the automatic control system, when the structure and parameters of the controlled object cannot be fully grasped, or it is difficult to obtain an accurate mathematical model, some traditional control theories are difficult to adopt. PID (proportional, differential, integral) controllers can be controlled by parameters such as proportional gain (Kp), integral time constant (Ti), and differential time constant (Td) because they do not depend on the mathematical model of the controlled object. , trial and error or empirical formula to determine, can be widely used. The PID controller is a linear controller that linearly combines the ratio, integral and derivative of the deviation between the system set value and the actual output value to form a control amount. In practical applications, a part of the proportional (P) regulator, proportional integral (PI) regulator, proportional integral derivative (PID) regulator, etc. may be formed according to the characteristics of the controlled object.

However, the setting of each control parameter (Kp, Ti, Td) of the PID controller is based on the "rule of thumb" obtained from the experience of skilled engineers. Taking the proportional regulator of the PID controller used to control the position of the robot arm in the robot as an example, the strength of the proportional regulator depends on the magnitude of the proportional gain Kp, and increasing the Kp can reduce the steady-state error. Poor, however, Kp over the assembly causes the controlled amount to oscillate, and even leads to system instability, while reducing Kp, the system response speed will be slower. In order to meet the requirements of system response speed and stability, and to determine a better Kp, engineers often need to experience the vibration of the arm by experience or by hand to adjust Kp until the system performance requirements are met. However, this practice takes a long time and requires a high level of skill for the engineer. In addition, when the initial condition changes when the process starts to start or the system introduces new interference, it is necessary to readjust the above various control parameters.

In view of the above, it is necessary to provide a control method and control device that can more conveniently adjust the control parameters of the PID controller to a preferred value to meet the system performance index requirements, and a robot having the control device.

A control method using a PID controller, comprising: the displacement sensing unit sensing a displacement signal of the controlled object to obtain an actual displacement value; the vibration sensing unit sensing a vibration signal of the controlled object; and the adjusting unit is configured according to the Adjusting the difference between the actual displacement value and the preset displacement value of the controlled object set by the PID controller, the vibration signal and the preset performance index of the control device, the control parameter including the proportional gain, And adjust the value range of the proportional gain, within the range of values, gradually adjust the proportional gain from a small value to a larger value, when the vibration signal obtained by the vibration sensing unit is greater than the set value, the adjustment unit reduces the ratio Gain, when the vibration signal obtained by the vibration sensing unit is less than the set value, the adjustment unit increases the proportional gain.

A control device using a PID controller includes a PID controller, a displacement sensing unit, a vibration sensing unit, and an adjustment unit. The displacement sensing unit is configured to acquire a displacement signal of the controlled object and feed the displacement signal to the PID controller. PID controller output control The signal controls the controlled object. The vibration sensing unit is configured to acquire the vibration signal of the controlled object. The adjusting unit adjusts the control parameter of the PID controller according to the difference between the actual displacement value corresponding to the displacement signal and the preset displacement value of the controlled object set by the PID controller, the vibration signal and the performance index preset by the control device . The PID controller includes a position control module, a speed control module and a current control module which are sequentially connected, and the adjustment unit is used for adjusting the proportional gain of the position control module.

A robot includes a mechanical arm, a stepping motor for driving the mechanical arm, a stepping motor driver for controlling the stepping motor, and the above control device. The PID controller of the above control device is disposed in the stepper motor driver. The displacement sensing unit is configured to sense the displacement of the mechanical arm to obtain the actual displacement value of the mechanical arm, and the vibration sensing unit is disposed on the mechanical arm for sensing the vibration of the mechanical arm to obtain the vibration signal. The adjusting unit adjusts the control parameter of the PID controller according to the difference between the actual displacement value and the preset displacement value of the mechanical arm set by the PID controller, the vibration signal and the performance index preset by the control device, and the control parameter includes a ratio Gain, and set the range of proportional gain when adjusting, within the range of values, gradually adjust the proportional gain from a small value to a larger value. When the vibration signal obtained by the vibration sensing unit is greater than the set value, the adjustment unit is reduced. The small proportional gain, when the vibration signal obtained by the vibration sensing unit is less than the set value, the adjusting unit increases the proportional gain, and the PID controller outputs a control signal to control the stepping motor.

The control device and the control method using the PID controller obtain the vibration signal reflecting the stability of the system by the vibration sensing unit, and obtain the displacement signal reflecting the steady state error of the system by the displacement sensing unit, and the adjusting unit combines the vibration signal and Displace the signal and adjust the control parameters of the PID controller according to the performance requirements of the control device. The above method can conveniently realize the dynamic adjustment and adjust the control parameters to Preferred value. By applying the above control method, the control device can adjust the control parameters of the PID controller according to the immediate response, and does not depend on the subjective judgment of the engineer, and is easy to obtain better parameters and can improve the efficiency of the adjustment. A robot having the above control device can have a high control precision.

100‧‧‧ Robot

11‧‧‧Base

12‧‧‧Rack

13‧‧‧First manipulator

14‧‧‧Second robotic arm

15‧‧‧3rd manipulator

16‧‧‧Connecting Department

21‧‧‧Stepper motor

200‧‧‧Control device

22‧‧‧Stepper motor driver

23‧‧‧ Displacement sensing unit

24‧‧‧Vibration sensing unit

25‧‧‧Sports Control Card

26‧‧‧Host

2231‧‧‧Location Control Module

2232‧‧‧Speed Control Module

2235‧‧‧ Current Control Module

261‧‧‧Adjustment unit

262‧‧‧Human interaction unit

Fig. 1 is a view of a robot having a control device using a PID controller of the present invention.

2 is a schematic diagram of an embodiment of a control device using a PID controller of the present invention.

FIG. 3 is a structural block diagram of an embodiment of a control device using a PID controller according to the present invention.

4 is a flow chart of a control method using a PID controller of the present invention.

The control method and control device of the PID controller and the robot having the same according to the present invention will be further described in detail below with reference to the accompanying drawings and embodiments. This embodiment is described by taking a control method and a control device using a PID controller applied to an industrial robot as an example.

FIG. 1 shows a robot 100. In this embodiment, the robot 100 is a six-axis industrial robot including a base 11, a frame 12 rotatably disposed on the base 11, a first mechanical arm 13 rotatably disposed on the frame 12, and a first A connecting portion 16 to which the mechanical arm 13 is rotatably coupled, a second mechanical arm 14 rotatably coupled to the connecting portion 16, and a third mechanical arm 15 rotatably coupled to the second mechanical arm 14.

The base 11 is used to mount the robot 100 to the floor or the support, and the frame 12 is rotatable about the first rotation axis a. The first robot arm 13, the second robot arm 14, and the third robot arm 15 can respectively rotate around the rotation axis. b, d, e rotate. The robot 100 further includes other two axes represented by c and f, wherein the sixth axis f can be mounted with a fixture, a tool or a detecting instrument. The device works.

Each end of the rotating shaft of the robot 100 is provided with a stepping motor. The output shaft of the stepping motor is connected with the robot arm to drive the arm to rotate. In FIG. 1 , only the rotating shaft e is mounted for driving the third arm. 15 stepper motor 21.

2 shows a schematic diagram of the control device 200 of the present invention applied to the robot 100 shown in FIG. 1 (only the control of the third robot arm 15 is taken as an example). The control device 200 includes a stepping motor driver 22, a displacement sensing unit 23, a vibration sensing unit 24, a motion control card 25, and a host computer 26.

The stepping motor driver 22 is configured to convert the pulse signal from the motion control card 25 into an angular displacement signal of the stepping motor 21 to move the robot arms of the robot 100 to a preset position. The stepping motor driver 22 includes a PID controller 223 disposed therein. The PID controller 223 includes a position loop, a speed loop, and a sequence control module 2231, a speed control module 2232, and a current control module 2235. The current loop constitutes a three-loop control circuit. The control parameters (Kp, Ti, Td) of the PID controller 223 can be set.

The displacement sensing unit 23 is configured to acquire the actual displacement value (the angle of rotation) of the third robot arm 15 , and the signal output end thereof is connected to the host 26 . The displacement sensing unit 23 used in this embodiment is a photoelectric encoder, which is mounted on the output shaft of the stepping motor 21 and rotates synchronously with the output shaft of the stepping motor 21, so that the synchronous rotation of the third robot arm 15 can be obtained. Signal.

The vibration sensing unit 24 is configured to sense the vibration of the third robot arm 15 , and the signal output end thereof is connected to the host 26 . The vibration sensing unit 24 used in this embodiment is a three-axis acceleration sensor, which is mounted on the third mechanical arm 15 for seating the third mechanical arm 15 in the space. The vibration in the three-axis direction is sensed, and the output signal includes the amplitude and vibration frequency signal of the third robot arm 15 in the three-axis direction.

The motion control card 25 is used to issue a control signal to the stepper motor driver 22 to drive the stepper motor 21. The motion control card 25 can generate pulse and direction signals, etc., and can perform automatic lifting speed and sensing of the origin signal. A motion control card 25 can individually control one or both of the plurality of stepper motor drivers 22. In this embodiment, a six-axis motion control card 25 that can simultaneously control six stepper motor drivers of the six-axis industrial robot 100 is employed.

The host 26 includes an adjustment unit 261 and a human-machine interaction unit 262. The adjusting unit 261 acquires the sensing signals of the displacement sensing unit 23 and the vibration sensing unit 24, and compares the preset displacement value of the third robot arm 15 set by the PID controller with the actual displacement value obtained by the displacement sensing unit 23. The system obtains the steady state position error of the system, and adjusts the control parameters (Kp, Ti, Td) of the preferred PID controller 223 in combination with the dynamic performance indicators required by the control device 200, and transmits the above preferred control parameters to the PID. The controller 223 is configured to achieve better control performance of the control device 200. In this embodiment, the preferred control parameters are transmitted through the serial port, and the preferred dynamic performance index refers to the stability of the system and the speed of response. The human-machine interaction unit 262 mainly displays the dynamic response of the control device 200, such as a time domain response map, by an image, and provides an interactive window for setting parameters of the control device 200.

The specific method for adjusting the above preferred control parameters is described below, and the Kp parameter adjustment of the PID controller of the third robot arm 15 of the robot 100 is taken as an example. The stepping motor driver 22 is set to the semi-automatic mode, and only There are Kp for dynamic setting.

FIG. 3 is a block diagram showing the structure of a control device 200 according to an embodiment of the present invention. PID controller The 223 supports position control, speed control and current control, and its output signal is used to control the stepping motor 21 connected thereto, and the input signal is the pulse and direction signal of the motion control card 25.

The adjusting unit 261 of the main unit 26 adjusts the control parameter Kp of the position control module 2231 according to the actual displacement value acquired by the displacement sensing unit 23 and the vibration signal acquired by the vibration sensing unit 24, so that the control device 200 has better stability. With faster response speeds, the required dynamic performance metrics are achieved.

The position control module 2231 immediately reacts the difference between the actual displacement value of the stepping motor 21 and the preset displacement value set by the PID controller, so that the displacement value changes in the direction of decreasing the deviation, and the strength of the control depends on Kp. size. Increasing Kp can increase the open-loop gain of the system, reduce the steady-state error, and increase the rapid response of the system. However, it is easy to reduce the stability of the system and increase the oscillation. By reducing the Kp value, the system response will be slower, but stability will increase. The preferred Kp should meet the requirements of system speed and stability.

The control method of the PID controller of the embodiment of the present invention can semi-automatically adjust the Kp parameter of the PID controller 223. Referring to FIG. 4, the control method includes the following steps:

Step S31: Setting the parameter adjustment mode. In this embodiment, the parameter adjustment mode of the PID controller 223 is set to a semi-automatic mode. In the semi-automatic mode, only the Kp of the position control module 2231 of the PID controller 223 can be adjusted.

Step S32: setting the load of the controlled object. In the present embodiment, the load of the six-axis industrial robot 100 is set to determine initial conditions of parameter setting and external disturbances.

Step S34: sensing the displacement signal of the controlled object. Sensing by the displacement sensing unit 23 The displacement signal of the three robot arms 15 is used to obtain the actual displacement value of the third robot arm 15.

Step S35: Sensing the vibration signal of the controlled object. The vibration signal of the third robot arm 15 is sensed by the vibration sensing device 25, and the vibration signal includes amplitude and frequency signals.

Step S36: The adjustment unit 261 obtains the vibration obtained by the vibration sensing unit 24 according to the difference between the actual displacement value of the robot arm 15 corresponding to the displacement signal acquired by the displacement sensing unit 23 and the preset displacement value set by the PID controller 223. The signal and the performance indicator of the control device 200 adjust and adjust the Kp value.

Specifically, in step S36, the value range of the control parameter Kp of the PID controller 223 may be first set, and within the range of values, the Kp is gradually adjusted from a smaller value to a larger value, and the adjustment process, such as vibration sensing. The vibration signal obtained by the unit 24 is strong, that is, the amplitude is large or the frequency is high, and the adjustment unit 261 automatically reduces the Kp. If the vibration signal is weak, the adjustment unit 261 automatically increases the Kp to speed up the response speed of the system. Until the vibration signal and the response speed fall within the set value range, so as to meet the requirements of system rapidity and stability, the Kp value is recorded, and the Kp value of the PID controller 223 is set by the serial port. As a preferred solution, the time domain response map of the observation control device 200 can be combined with the adjustment (the human-computer interaction unit 262 of the host 26 can display the time domain response map), so that the system can be visually observed after the parameter adjustment. Respond to the situation and adjust the Kp value accordingly.

Step S37: changing the load of the robot 100, that is, changing its initial condition and external disturbance, repeating steps S32 to S36 to obtain a preferred Kp value under the load and saving the Kp value.

By repeating step S37, a better Kp value corresponding to each load under different loads can be obtained. As a preferred solution, the control method may further include establishing the load and The step S38 of the Kp value knowledge base corresponding thereto can be stored in the host 26. When it is necessary to set the Kp value of the PID controller 223 of the other robot 100, the knowledge base established above can be used to directly select the matching of the load, the vibration value and the steady-state error value (response speed). The Kp value, thereby reducing the adjustment time, can be further achieved by fuzzy logic.

The above only gives the adjustment method of the Kp of the position control module 2231 of the stepping motor driver 223 on the third axis e of the robot 100. The PID control parameters of the stepping motor driver on the other rotating axes of the robot 100 can be the same. The method is set in order.

The control method obtains the vibration signal by the vibration sensing unit 24, and combines the vibration signal with the displacement signal acquired by the displacement sensing unit 23 to semi-automatically adjust the Kp parameter of the position control module 2231 of the stepping motor driver 223.

In summary, the present invention has indeed met the requirements of the invention patent, and has filed a patent application according to law. However, the above description is only a preferred embodiment of the present invention, and it is not possible to limit the scope of the patent application of the present invention. Equivalent modifications or variations made by persons skilled in the art in light of the spirit of the invention are intended to be included within the scope of the following claims.

Claims (8)

A control method using a PID controller, comprising: the displacement sensing unit sensing a displacement signal of the controlled object to obtain an actual displacement value; the vibration sensing unit sensing a vibration signal of the controlled object; and the adjusting unit is configured according to the Adjusting the difference between the actual displacement value and the preset displacement value of the controlled object set by the PID controller, the vibration signal and the preset performance parameter of the control system, the control parameter includes a proportional gain, and the control parameter includes a proportional gain, and During the adjustment, the range of the proportional gain is set, and within the range of values, the proportional gain is gradually adjusted from a smaller value to a larger value. When the vibration signal obtained by the vibration sensing unit is greater than the set value, the adjustment unit reduces the proportional gain. When the vibration signal obtained by the vibration sensing unit is less than the set value, the adjusting unit increases the proportional gain. The control method using the PID controller as described in claim 1, wherein the control method further comprises the steps of: setting a load of the controlled object; and adjusting the unit according to the actual displacement value and being controlled by the PID controller The difference between the preset displacement values of the object, the vibration signal and the performance index of the preset control system adjust the control parameters of the PID controller under the load. The control method using the PID controller as described in claim 2, wherein the control method further comprises the steps of: setting different loads, and establishing a knowledge base according to control parameters of the PID controller corresponding to each load. A control device using a PID controller, comprising a PID controller and a displacement sensing unit, the displacement sensing unit is configured to acquire a displacement signal of the controlled object and feed the displacement signal to the PID controller, and the PID controller outputs the control The signal controls the controlled object, wherein the control device further includes vibration a sensing unit and an adjusting unit, wherein the vibration sensing unit is configured to acquire a vibration signal of the controlled object, and the adjusting unit is configured according to an actual displacement value corresponding to the displacement signal and a preset displacement of the controlled object set by the PID controller The difference between the value, the vibration signal and the preset performance index of the control device adjust the control parameter of the PID controller, and the PID controller comprises a position control module, a speed control module and a current control module which are sequentially connected, the adjustment The unit is used to adjust the proportional gain of the position control module. A control device using a PID controller as described in claim 4, wherein the displacement sensing unit is a photoelectric encoder. The control device using the PID controller as described in claim 4, wherein the vibration sensing unit is an acceleration sensor for acquiring a vibration signal of a three-axis direction of the space coordinate of the controlled object. A control device using a PID controller as described in claim 6 wherein the vibration signal comprises an amplitude and a vibration frequency signal. A robot comprising a mechanical arm, a stepping motor for driving the robot arm, and a stepping motor driver for controlling the stepping motor, wherein the robot further comprises the control device according to any one of claims 4 to 7. The PID controller is disposed in the stepping motor driver, the displacement sensing unit is configured to sense the displacement of the robot arm to obtain an actual displacement value of the robot arm, and the vibration sensing unit is disposed on the robot arm for sensing Measuring the vibration of the arm to obtain a vibration signal, the adjusting unit is based on the difference between the actual displacement value and the preset displacement value of the arm set by the PID controller, the vibration signal, and a preset performance index of the control device Adjusting the control parameter of the PID controller, the control parameter includes a proportional gain, and setting a range of the proportional gain during the adjustment, in which the proportional gain is gradually adjusted from a smaller value to a larger value, when the vibration is sensed The vibration signal obtained by the measuring unit is greater than the set value, and the adjusting unit reduces the proportional gain. When the vibration signal obtained by the vibration sensing unit is less than the set value, the adjusting unit is increased. Gain embodiment, the PID controller outputs a control signal for controlling the stepping motor.