阅读说明：本技术 一种速度伺服系统的控制方法 (Control method of speed servo system ) 是由 姚坤鹏 张金萍 殷飞 娄亚飞 吴琛 于 2019-09-26 设计创作，主要内容包括：一种速度伺服系统的控制方法,包括以下步骤：获得当前速度控制迭代周期的目标速度,记为S1；根据所述S1计算出当前速度控制迭代周期内的虚拟位移,获得该虚拟位移与该时刻被控对象反馈位置的差值,并将该差值记为A1；根据A1计算出目标电流,该目标电流被处理后作用在被控对象上；获得下一速度控制迭代周期的目标速度,记为S2；根据所述S2计算出下一个速度控制迭代周期内的虚拟位移,获得该虚拟位移与该时刻被控对象反馈位置的差值,并将该差值记为A2；根据A2计算出目标电流,该目标电流被处理后作用在被控对象上。在保证控制精度的前提下,提高了位置控制功能的响应速度,改善了位置控制功能的动态性能。(A method of controlling a velocity servo system, comprising the steps of: obtaining a target speed of a current speed control iteration cycle, and recording as S1; calculating the virtual displacement in the current speed control iteration cycle according to the S1, obtaining the difference value between the virtual displacement and the feedback position of the controlled object at the moment, and recording the difference value as A1; calculating a target current according to A1, wherein the target current is processed and acts on a controlled object; obtaining a target speed of the next speed control iteration cycle, and recording as S2; calculating the virtual displacement in the next speed control iteration cycle according to the S2, obtaining the difference value between the virtual displacement and the feedback position of the controlled object at the moment, and recording the difference value as A2; and calculating a target current according to A2, wherein the target current is processed and acts on the controlled object. On the premise of ensuring the control precision, the response speed of the position control function is improved, and the dynamic performance of the position control function is improved.)

1. A method of controlling a velocity servo system, comprising the steps of:

step 1: obtaining a target speed of a current speed control iteration cycle, and recording as S1;

step 2: calculating the virtual displacement in the current speed control iteration cycle according to the S1, obtaining the difference value between the virtual displacement and the feedback position of the controlled object at the moment, and recording the difference value as A1;

and step 3: calculating a target current according to A1, wherein the target current is processed and acts on a controlled object;

and 4, step 4: obtaining a target speed of the next speed control iteration cycle, and recording as S2;

and 5: calculating the virtual displacement in the next speed control iteration cycle according to the S2, obtaining the difference value between the virtual displacement and the feedback position of the controlled object at the moment, and recording the difference value as A2;

step 6: calculating a target current according to A2, wherein the target current is processed and acts on a controlled object; jump to step 4.

2. A control method of a velocity servo system according to claim 1, characterized in that: in the step 5, when the difference value between the virtual displacement and the feedback position of the controlled object is greater than a certain threshold value B, recording the value of A1 or A2 as the threshold value B, and executing the step 6; otherwise, step 6 is performed directly.

3. A control method of a velocity servo system according to claim 1, characterized in that: in the step 1 and the step 4, the target position is received, the distance between the target position and the feedback position of the controlled object at the moment is obtained, and the target speed is obtained according to the distance and a set strategy.

4. A control method of a velocity servo system according to claim 1, characterized in that: in the step 3 and the step 6, the target current minus the motor feedback current is sequentially acted on the controlled object through the PID operation, the motor driving circuit and the motor.

Technical Field

The invention relates to the technical field of speed servo system control based on a position sensor, in particular to a control method of a speed servo system.

Background

Servo systems, also known as servo systems, are feedback control systems used to accurately follow or replicate a process. The servo system is an automatic control system which can make the output controlled quantity of the position, the direction, the state and the like of an object follow the arbitrary change of an input target (or a given value). It has wide application in aerospace, military, industrial and agricultural fields.

In a speed servo actuator, the conventional implementation is a two-closed-loop method, i.e. a typical two-closed-loop control method of rotating speed and current. The method needs to receive a speed instruction and then realize speed control through regulation of two closed loops of rotating speed and current. The control quantity needs to be transmitted in different closed loops, so that the adjusting speed is slow and the dynamic error is large.

Disclosure of Invention

The invention provides a control method of a speed servo system, which improves the response speed of a speed servo actuating mechanism based on a position sensor to a speed control command.

A method of controlling a velocity servo system, comprising the steps of:

step 1: obtaining a target speed of a current speed control iteration cycle, and recording as S1;

step 2: calculating the virtual displacement in the current speed control iteration cycle according to the S1, obtaining the difference value between the virtual displacement and the feedback position of the controlled object at the moment, and recording the difference value as A1;

and step 3: calculating a target current according to A1, and sequentially performing PID operation, a motor drive circuit and a motor on a controlled object after subtracting the motor feedback current from the target current;

and 4, step 4: obtaining a target speed of the next speed control iteration cycle, and recording as S2;

and 5: calculating the virtual displacement in the next speed control iteration cycle according to the S2, obtaining the difference value between the virtual displacement and the feedback position of the controlled object at the moment, and recording the difference value as A2;

step 6: calculating a target current according to A2, and sequentially performing PID operation, a motor drive circuit and a motor on a controlled object after subtracting the motor feedback current from the target current; jump to step 4.

Further comprises the following steps: in the step 5, when the difference between the virtual displacement and the feedback position of the controlled object is greater than a certain threshold B, and when the difference between the virtual displacement and the feedback position of the controlled object is greater than the certain threshold B, the value of a1 or a2 is recorded as the threshold B, and step 6 is executed; otherwise, step 6 is performed directly.

Further comprises the following steps: in the step 1 and the step 4, receiving a target position, obtaining a distance between the target position and a feedback position of the controlled object at the moment, and obtaining a target speed according to a set strategy according to the distance; the target speed is calculated from the target bit permutation to execute the speed control method of the present invention.

The invention has the beneficial effects that: a new control algorithm is adopted, and a virtual position instruction is calculated by comparing the received speed instructions; the virtual position instruction is compared with the actual position after amplitude limiting, and the position deviation for control is calculated; and calculating the applied motor current according to the position deviation so as to solve the problem of slow reaction speed of the traditional two closed loops. In the operation process of the compensation algorithm, the requirement on the resolution ratio of the position sensor is reduced, and the response speed of the position servo executing mechanism to the position instruction is improved. When the target position is approached, the method can be switched to the three-closed-loop control method smoothly according to the requirement, so that the adjustment precision is ensured, meanwhile, on the premise of ensuring the control precision, the response speed of the position control function is improved, and the dynamic performance of the position control function is improved.

Drawings

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

fig. 2 is a main system block diagram of the present invention.

Detailed Description

The present invention will be described in detail with reference to the accompanying drawings. It should be noted that the terms of orientation such as left, middle, right, up and down in the examples of the present invention are only relative concepts or reference to the normal use state of the product, and should not be considered as limiting.

A method of controlling a velocity servo system, as shown in fig. 1, comprising the steps of:

step 1: obtaining a target speed of a current speed control iteration cycle, and recording as S1;

step 2: calculating the virtual displacement in the current speed control iteration cycle according to the S1, obtaining the difference value between the virtual displacement and the feedback position of the controlled object at the moment, and recording the difference value as A1;

and step 3: calculating a target current according to A1, and sequentially performing PID operation, a motor drive circuit and a motor on a controlled object after subtracting the motor feedback current from the target current;

and 4, step 4: obtaining a target speed of the next speed control iteration cycle, and recording as S2;

and 5: calculating the virtual displacement in the next speed control iteration cycle according to the S2, obtaining the difference value between the virtual displacement and the feedback position of the controlled object at the moment, and recording the difference value as A2;

step 6: calculating a target current according to A2, and sequentially performing PID operation, a motor drive circuit and a motor on a controlled object after subtracting the motor feedback current from the target current; jump to step 4.

In the step 1 and the step 4, a target position instruction is received, the distance between the target position and the feedback position of the controlled object at the moment is obtained, and the target speed is obtained according to the distance and a set strategy.

In the step 5, when the difference between the virtual displacement and the feedback position of the controlled object is greater than a certain threshold B, and when the difference between the virtual displacement and the feedback position of the controlled object is greater than the certain threshold B, the value of a1 or a2 is recorded as the threshold B, and step 6 is executed; otherwise, step 6 is performed directly. And limiting the target current so as to protect the motor.

The three closed loop position control method has a slow response speed but can eliminate steady state position errors. The invention adopts direct speed control to have faster reaction speed, but steady-state position error may exist. In order to combine the advantages of the two methods, the control method needs to be switched under specific conditions to obtain higher control effect, and the switching process is controlled by the B module.

The main working principle of the invention is as follows: as shown in fig. 2, the speed control part of the present invention is mainly composed of three parts, wherein part a functions to calculate a virtual target position signal by a target speed, and part B functions to calculate a difference pos _ err between the virtual target position signal and a feedback position; and the part C calculates the target current according to the set difference-current curve according to the size of the difference pos _ err. The calculation method of the part A is that the step length Pstep of virtual position change of each iteration, namely the virtual target position signal, is calculated through the speed control iteration frequency Fs and the given speed Vref. And circulating in such a way until all speed control iteration cycles in the target speed are executed.

In addition, it is worth to be noted that the conventional servo system adopts a control mechanism with three closed loops, namely a position loop, a speed loop and a moment loop. The inputs to the position loop are the target position and the actual position, and the output is the target velocity. The position ring calculates how high the current servo system should operate to achieve the control target, i.e. the target speed, according to the difference between the target position and the actual position and according to a set algorithm (table lookup or calculation or other). However, the position ring only calculates the target speed and does not adjust the system operation speed.

The input of the speed loop is the target speed and the actual speed, and the output is the target torque (target current). The speed loop calculates how much torque the current servo system should operate at, i.e., the target torque, according to the interpolation of the target speed and the actual speed. However, the speed loop also only calculates the target torque, but does not adjust the actual torque.

The inputs to the torque ring are the target torque and the actual torque. And adjusting the control quantity according to the difference value of the target torque and the target torque so as to enable the output torque of the power source of the servo system to track the change of the target torque. In the operation process, the division of work of the three closed loops is clear, and each link is only responsible for the state of the link. If the position ring only ensures that the actual position can track the change of the target position, the method is to change the speed of the target; the speed ring only ensures that the actual speed can track the change of the target speed, and the method is to change the magnitude of the target torque; the torque ring only ensures that the actual torque can track the change of the target torque, and the means is to change the control quantity of the power source of the servo system.

The method of the invention focuses on a speed loop, and according to the magnitude of the target speed and the iteration period of the controller, the moving distance of the virtual target position in each control period is calculated, and the virtual target position is compared with the actual position to determine the output of the speed loop. Of primary concern is how to make the actual speed follow the change in target speed.

The foregoing illustrates and describes the principles, general features, and advantages of the present invention. It will be understood by those skilled in the art that the present invention is not limited to the embodiments described above, which are described in the specification and illustrated only to illustrate the principle of the present invention, but that various changes and modifications may be made therein without departing from the spirit and scope of the present invention, which fall within the scope of the invention as claimed. The scope of the invention is defined by the appended claims and equivalents thereof.