CN106249600A - The model reference adaptive position control method of supersonic motor and system - Google Patents

Abstract

The invention relates to a model reference adaptive position control method and system of an ultrasonic motor, belonging to the technical field of ultrasonic motor control. The method includes: outputting an actual position value y _p according to the position command y _r ; outputting a position reference value y _m according to the position command y _r ; outputting a reference error e ₁ according to the actual position value y _p and the position reference value y _m ; Adjust the actual position value y _p according to the reference error e ₁ ; according to the position reference value y _m , make a differential to obtain the speed reference value n _m corresponding to the position reference value y _m ; when the speed reference value n _m is greater than the maximum speed N of the ultrasonic motor, The position reference value y _m is replaced by the corresponding position reference value y _m when the rotational speed reference value n _m is not greater than N. By adopting the method and system of the present invention, the reference model can be better matched with the ultrasonic motor with a maximum speed limit, which fundamentally limits the position control overshoot and oscillation process caused by the large saturation of the model reference adaptive position output, and improves the control performance.

Description

Model reference adaptive position control method and system for ultrasonic motor

technical field

The invention relates to a model reference adaptive position control method and system of an ultrasonic motor, belonging to the technical field of ultrasonic motor control.

Background technique

Ultrasonic motors have broad application prospects in the fields of automotive electronics, precision instruments, robots, aerospace, and weaponry. However, due to the nonlinearity of the piezoelectric material inside the ultrasonic motor and the frictional transmission of mechanical energy between the stator and rotor, the ultrasonic motor has stronger time-varying nonlinear operating characteristics than the traditional electromagnetic motor. At the same time, the ultrasonic motor drive circuit works in the switch state, and its control relationship also has nonlinear characteristics, which makes the time-varying nonlinearity of the ultrasonic motor system more obvious, and it is difficult to obtain good motion control performance. In order to improve its control performance, a control strategy with adaptive characteristics should be adopted to adjust the controller parameters or structure in real time.

At present, control strategies such as model reference adaptive control (MRAC), fuzzy control, and neural network control have been used in the motion control research of ultrasonic motors. For example, the ultrasonic motor model reference adaptive (MRAC) position control system is designed according to the traditional design method, as shown in Figure 1. In the figure, y _r is the rotation angle of the motor (that is, the given value of the position), and the position model refers to the given value of the motor speed n _r by the adaptive position controller. Because the motors actually used will have a maximum allowable speed value (for example, the maximum speed value of the experimental motor used is 120r/min), and n _r may exceed this limit, so set the "speed given value" after the position controller "Limiting" link, which limits the value of n _r below the maximum speed value allowed by the motor. W _p (s) is the transfer function of the speed control inner loop including the ultrasonic motor, and its output is the actual speed n _p of the motor, and the motor speed is passed through the integration link 1/s to obtain the rotation angle of the motor, that is, the actual position value y _p . In the figure, W _m (s) is a reference model, and its output is a motor position reference value y _m . The difference between y _m and _{y p} is obtained to obtain the reference error e ₁ , which is used to adjust the adjustable parameters in the model reference adaptive position controller online to realize adaptive control.

Taking the Shinsei USR60 two-phase traveling wave ultrasonic motor as the control object, the designed MRAC position control strategy is programmed to study its control performance.

Figure 2 shows the position output response curves when the given value of the position step is 360°, and the transfer functions of the reference model are respectively W _m1 with a slower response speed and W _m2 with a faster response speed. It can be seen from the solid line in Figure 2 that when the reference model is selected as W _m1 , the actual position value can track the output of the reference model well, and the output has no overshoot, but the response speed is slow, and the adjustment time is about 3.575s, which does not conform to the ultrasonic The short-term and fast working characteristics of the motor; when the reference model is selected as W _m2 , the dotted line in Figure 2 indicates that the position output has a large overshoot, but the adjustment time is only 0.936s. Overshoot occurs because the performance of the selected reference model is too high, and the adjustable system will make the position MRAC controller too strong in the process of trying to track the change of the reference model. Since the output of the position MRAC controller is the reference speed, and the speed limit of the ultrasonic motor is 120r/min, the control system only limits the output speed of the controller but has no effect on the calculation process of the control amount, resulting in relatively large position output. Big overshoot.

Contents of the invention

The purpose of the present invention is to provide a model reference adaptive position control method and system for an ultrasonic motor to solve the problems of position output overshoot and oscillation caused by the speed limit of the ultrasonic motor.

In order to achieve the above object, the model reference adaptive position control method of the ultrasonic motor of the present invention includes: outputting an actual position value _yp according to the position command _yr of the ultrasonic motor _; outputting a position reference value according to the position command yr of the ultrasonic motor y _m ; output a reference error e ₁ according to the actual position value y _p and the position reference value y _m , the reference error e ₁ is the difference between the position reference value y _m and the actual position value y _p ; adjust the actual position according to the reference error e ₁ value y _p ; it also includes differentially obtaining the speed reference value n _m corresponding to the position reference value y _m according to the position reference value y _m ; when the speed reference value n _m is greater than the actual maximum speed N of the ultrasonic motor, the position reference value y _m is replaced by the corresponding position reference value y _m when the speed reference value n _m is not greater than the actual maximum speed N of the ultrasonic motor.

Furthermore, the step response curve of the model reference adaptive position output of the ultrasonic motor includes three areas in turn, which are the start-up low-speed area, the speed-up area, and the speed-down area, wherein the speed reference value n of the start-up low-speed area and the speed drop area _m is not greater than the actual maximum rotational speed N of the ultrasonic motor, and the rotational speed reference value n _m in the rotational speed rising zone is greater than the actual maximum rotational speed N of the ultrasonic motor.

Further, it also includes performing linear interpolation on the position reference value y _m in the speed drop zone:

Suppose the interpolation interval is [k1, N], the sampling time is Ts, y(k) and y(k+1) represent the position reference value output by the reference model at time k and k+1 respectively, T(k) and T( k+1) represent the time points of time k and k+1 respectively, the interpolation point is represented by (x, y), and x=T(k)+a*Ts, a is the interpolation interval, then the interpolation calculation formula can be Expressed as:

$\begin{array}{c}\mathrm{<span\; class="notranslate">\; the\; y</span>}<span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; the\; y</span>}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; k</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; +</span>\frac{\mathrm{<span\; class="notranslate">\; the\; y</span>}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; k</span>}<span\; class="notranslate">\; +</span>\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; the\; y</span>}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; k</span>}<span\; class="notranslate">\; )</span>}{\mathrm{<span\; class="notranslate">\; T</span>}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; k</span>}<span\; class="notranslate">\; +</span>\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; T</span>}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; k</span>}<span\; class="notranslate">\; )</span>}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; T</span>}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; k</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; +</span>\mathrm{<span\; class="notranslate">\; a</span>}<span\; class="notranslate">\; *</span>\mathrm{<span\; class="notranslate">\; T</span>}\mathrm{<span\; class="notranslate">\; the\; s</span>}<span\; class="notranslate">\; )</span>\\ <span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; the\; y</span>}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; k</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; +</span>\mathrm{<span\; class="notranslate">\; the\; y</span>}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; k</span>}<span\; class="notranslate">\; +</span>\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; the\; y</span>}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; k</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; *</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; k</span>}<span\; class="notranslate">\; +</span>\mathrm{<span\; class="notranslate">\; a</span>}<span\; class="notranslate">\; )</span>\end{array}$

In the formula, when y _r <360°, 0<a<1; when y _r =360°, a=1; when y _r >360°, a>1.

Further, the driving voltage frequency of the ultrasonic motor is used as the adjustment variable.

The model reference adaptive position control system of the ultrasonic motor of the present invention includes: a unit for outputting an actual position value _yp according to the position command _yr of the ultrasonic motor; for outputting a position reference according to the position command _yr of the ultrasonic motor The unit of value y _m ; used to output a unit of reference error e ₁ according to the actual position value y _p and the position reference value y _m , the reference error e ₁ is the difference between the position reference value y _m and the actual position value y _p ; use It is a unit for adjusting the actual position value y _p according to the reference error e ₁ ; it also includes a unit for differentially obtaining the speed reference value n _m corresponding to the position reference value y _m according to the position reference value y _m ; it is used when the speed reference When the value n _m is greater than the actual maximum speed N of the ultrasonic motor, the position reference value y _m is replaced by the corresponding position reference value y _m when the speed reference value n _m is not greater than the actual maximum speed N of the ultrasonic motor.

Furthermore, the step response curve of the model reference adaptive position output of the ultrasonic motor includes three areas in turn, which are the start-up low-speed area, the speed-up area, and the speed-down area, wherein the speed reference value n of the start-up low-speed area and the speed drop area _m is not greater than the actual maximum rotational speed N of the ultrasonic motor, and the rotational speed reference value n _m in the rotational speed rising zone is greater than the actual maximum rotational speed N of the ultrasonic motor.

Further, it also includes a unit for performing linear interpolation on the position reference value y _m in the rotational speed drop zone:

Suppose the interpolation interval is [k1, N], the sampling time is Ts, y(k) and y(k+1) represent the position reference value output by the reference model at time k and k+1 respectively, T(k) and T( k+1) represent the time points of time k and k+1 respectively, the interpolation point is represented by (x, y), and x=T(k)+a*Ts, a is the interpolation interval, then the interpolation calculation formula can be Expressed as:

$\begin{array}{c}\mathrm{<span\; class="notranslate">\; the\; y</span>}<span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; the\; y</span>}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; k</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; +</span>\frac{\mathrm{<span\; class="notranslate">\; the\; y</span>}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; k</span>}<span\; class="notranslate">\; +</span>\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; the\; y</span>}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; k</span>}<span\; class="notranslate">\; )</span>}{\mathrm{<span\; class="notranslate">\; T</span>}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; k</span>}<span\; class="notranslate">\; +</span>\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; T</span>}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; k</span>}<span\; class="notranslate">\; )</span>}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; T</span>}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; k</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; +</span>\mathrm{<span\; class="notranslate">\; a</span>}<span\; class="notranslate">\; *</span>\mathrm{<span\; class="notranslate">\; T</span>}\mathrm{<span\; class="notranslate">\; the\; s</span>}<span\; class="notranslate">\; )</span>\\ <span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; the\; y</span>}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; k</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; +</span>\mathrm{<span\; class="notranslate">\; the\; y</span>}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; k</span>}<span\; class="notranslate">\; +</span>\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; the\; y</span>}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; k</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; *</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; k</span>}<span\; class="notranslate">\; +</span>\mathrm{<span\; class="notranslate">\; a</span>}<span\; class="notranslate">\; )</span>\end{array}$

In the formula, when y _r <360°, 0<a<1; when y _r =360°, a=1; when y _r >360°, a>1.

Further, the driving voltage frequency of the ultrasonic motor is used as the adjustment variable.

The beneficial effects of the present invention are: adopting the model reference adaptive position control method and system of the ultrasonic motor of the present invention enables the reference model to better match with the motor with the maximum rotational speed limit while reflecting the control expectation, thereby in The position control overshoot and oscillation process caused by the large saturation of the output of the model reference adaptive position controller are fundamentally limited, and the control performance is improved.

Since the present invention adopts the motor drive voltage frequency as the adjustment variable, the operation efficiency of the ultrasonic motor system and the instability of the motor rotation position caused when the drive voltage phase difference is used as the adjustment variable are avoided, thereby improving the position control performance of the motor.

Description of drawings

Figure 1 is a structural block diagram of a traditional ultrasonic motor position control system;

Figure 2 is the corresponding position step response curve of the traditional ultrasonic motor position control system;

Fig. 3 is the structural block diagram of the position control system of embodiment 1 of the model reference adaptive position control method of the ultrasonic motor;

Fig. 4 is the position step response curve of the reference model of the model reference adaptive position control method embodiment 1 of the ultrasonic motor;

Fig. 5 is the rotational speed output curve of the reference model of the model reference adaptive position control method embodiment 1 of the ultrasonic motor;

Fig. 6 is the position step response curve of the model reference adaptive position control method embodiment 1 of the ultrasonic motor;

Fig. 7 is the multi-position step response curve of the model reference adaptive position control method embodiment 1 of the ultrasonic motor;

Fig. 8 is a multi-position step response curve of Embodiment 2 of the model reference adaptive position control method of an ultrasonic motor.

detailed description

The present invention will be further described below in conjunction with accompanying drawing.

Example 1 of a model reference adaptive position control method for an ultrasonic motor

The model reference adaptive position control method of the ultrasonic motor of the present embodiment 1, as shown in Figure 3, outputs an actual position value y _p according to the position command y _r of the ultrasonic motor; outputs a position reference according to the position command y _r of the ultrasonic motor value y _m ; according to the actual position value y _p and the position reference value y _m , output a reference error e ₁ , the reference error e ₁ is the difference between the position reference value y _m and the actual position value y _p ; adjust the actual position according to the reference error e ₁ position value y _p ; it also includes differentially obtaining the speed reference value n _m corresponding to the position reference value y _m according to the position reference value y _m ; when the speed reference value n _m is greater than the actual maximum speed N of the ultrasonic motor, the position reference The value y _m is replaced by the corresponding position reference value y _m when the speed reference value n _m is not greater than the actual maximum speed N of the ultrasonic motor.

In order to facilitate the analysis of the influence of the reference model on the control performance, Figure 4 shows the simulation curve of the step response of the reference model at a given 360°, and Figure 5 shows the corresponding speed output curve. The solid line in Fig. 4 is the step response simulation curve of the present embodiment 1, the dotted line represents the step response simulation curve when the reference model is _Wm2 , and the dotted line represents the step response simulation curve when the reference model is _Wm1 . Taking the maximum speed of the reference model as 120r/min as the boundary, the step response curve when the reference model is W _m2 can be divided into three areas, namely the low speed area when the motor starts (the OA area in Figure 4), and the speed rising area (Area AB in Figure 4) and the speed drop zone (BE area in Figure 4) when the motor is about to reach a steady state position. Referring to Figure 5, the OA region is the initial stage of the position step response, the speed output is lower than 120r/min, the AB region is the rising stage of the position response, and the speed output during the period is higher than 120r/min, and the BE region indicates that the position output is close to the given position, the speed of the reference model is reduced to less than 120r/min.

Since the speed output of the reference model in the OA region is lower than 120r/min, which is within the operable range of the motor, the value of the OA region is still used in the initial stage of the output of the reference model in Embodiment 1. The ultrasonic motor model reference adaptive position control method mainly improves the AB region where the speed increases and the BE region where the speed decreases.

The speed output in the AB area is higher than 120r/min, that is, it exceeds the maximum operating speed allowed by the motor. The part of the reference model whose speed output is higher than 120r/min is replaced by a speed output equal to or slightly lower than 120r/min, as shown in Figure 4 It is 120r/min instead of the speed output in the AB area, as shown in the AC area on the solid line curve in Figure 4. Obviously, after this change, the speed is relatively low, and the position rises relatively slowly. The position output only reaches the position output value corresponding to point C within the same time period, and it will take a certain amount of time to reach the position output value corresponding to point B. In order to achieve position tracking, the improved reference model still keeps running at a constant speed until it reaches the position output at the same height as point B, which is shown by point D on the solid line curve in Figure 4. After the position response curve reaches point D, the position output in the DE area has approached the given value, the motor speed drops from 120r/min to zero, and the speed is within the allowable operating speed range of the motor. Therefore, the output of the DE region in the model reference adaptive position control method still uses the output of the BE region of the original reference model. By making such an improvement on the output of the reference model, the position overshoot phenomenon caused by the too fast response speed of the reference model and the strong control effect is avoided, which can also be seen from Figure 5. In Fig. 5, the dotted line represents the speed change process when the reference model W _m2 is used, and the speed output changes greatly in the AB region, with a maximum of about 700r/min; if this reference model is used, the position output must be caused by severe control effects. overshoot. The speed output after adopting the model reference adaptive position control method is shown by the solid line in Figure 6, and the speed is always within the allowable range of the motor.

Example 2 of a model reference adaptive position control method for an ultrasonic motor

The difference between Embodiment 2 of the model reference adaptive position control method for an ultrasonic motor of the present invention and Embodiment 1 of the model reference adaptive position control method for an ultrasonic motor is that it also includes performing linear interpolation on the output of the reference model in the rotational speed drop zone The unit of : perform linear interpolation on the output of the reference model in the speed drop area, and the specific realization is as follows:

Let the interpolation interval be [k1, N], and the sampling time be Ts. y(k) and y(k+1) represent the reference model output at time k and k+1, respectively, and T(k) and T(k+1) represent the time points at time k and k+1, respectively. The interpolation point is represented by (x, y), and x=T(k)+a*Ts, a is the interpolation interval.

Then the interpolation formula can be expressed as:

$\begin{array}{c}\mathrm{<span\; class="notranslate">\; the\; y</span>}<span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; the\; y</span>}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; k</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; +</span>\frac{\mathrm{<span\; class="notranslate">\; the\; y</span>}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; k</span>}<span\; class="notranslate">\; +</span>\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; the\; y</span>}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; k</span>}<span\; class="notranslate">\; )</span>}{\mathrm{<span\; class="notranslate">\; T</span>}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; k</span>}<span\; class="notranslate">\; +</span>\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; T</span>}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; k</span>}<span\; class="notranslate">\; )</span>}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; T</span>}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; k</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; +</span>\mathrm{<span\; class="notranslate">\; a</span>}<span\; class="notranslate">\; *</span>\mathrm{<span\; class="notranslate">\; T</span>}\mathrm{<span\; class="notranslate">\; the\; s</span>}<span\; class="notranslate">\; )</span>\\ <span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; the\; y</span>}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; k</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; +</span>\mathrm{<span\; class="notranslate">\; the\; y</span>}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; k</span>}<span\; class="notranslate">\; +</span>\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; the\; y</span>}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; k</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; *</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; k</span>}<span\; class="notranslate">\; +</span>\mathrm{<span\; class="notranslate">\; a</span>}<span\; class="notranslate">\; )</span>\end{array}<span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; )</span>$

In the formula, when y _r <360°, 0<a<1; when y _r =360°, a=1; when y _r >360°, a>1.

The model of the ultrasonic motor refers to the step response curves of Embodiment 1 of the adaptive position control method under other given position values, as shown in FIG. 7 , and Table 1 gives the corresponding performance index parameters. It can be seen from Figure 7 that after using the model reference adaptive position control method, the tracking control of different positions can be realized, but when the position setting is small, the position output has overshoot, and when the position setting is large, the steady-state fluctuation is relatively small. Big.

Table 1 Performance indicators under different step settings (e<5%)

Analyzing the data in Table 1, it can also be seen that the position output is prone to overshoot when the position given value is small, indicating that the control effect of the position controller is still relatively strong; while the position output has no overshoot when the position given value is large , but the position fluctuates greatly in steady state, indicating that the control action is frequent. This is because in the entire position control range, when the speed of the reference model is lower than 120r/min, it is selected according to the expected speed output when the position given value is 360°. In the process of setting the value, the speed is usually relatively low and the response speed is slow. If the response speed of the reference model is too fast when it is close to the steady state, in order to track the changes of the reference model, the controller will have a greater control effect. Because the motor The speed is limited, which leads to overshooting of the position output; when the position reference value is large, the response speed when the speed is lower than 120r/min is usually faster than that of 360°. If the original reference model is used, the response will be The slower the speed, the longer the adjustment time of the step response.

In Embodiment 2, linear interpolation is performed on the output of the reference model when the rotational speed is lower than 120 r/min, that is, linear interpolation is used to enlarge or reduce the output of the reference model in the speed drop interval. After such improvement to the offline output of the reference model, when the given position value is small, the response speed becomes slower when it is close to the steady state to suppress overshoot; The response speed can be accelerated, improving the overall response speed of the system.

Figure 8 shows the step response of the improved reference model when the position reference value is different. It can be seen from the figure that there is no overshoot in the position output, and there is no steady-state output when the position reference value is large. fluctuation. Table 2 gives the corresponding performance index values, and the data in the table also verifies the previous analysis.

Table 2 Performance indicators under different step settings (e<5%)

Embodiment 3 of a model reference adaptive position control method for an ultrasonic motor

The difference between Embodiment 3 of the model reference adaptive position control method for ultrasonic motors of the present invention and Embodiment 1 of the model reference adaptive position control method for ultrasonic motors is that the motor drive voltage frequency is used as the adjustment variable of the position controller module.

Using the motor drive voltage frequency as the adjustment variable avoids the problem of the operation efficiency of the ultrasonic motor system and the instability of the motor rotation position caused by using the drive voltage phase difference as the adjustment variable, thereby improving the position control performance of the motor.

Embodiment of model reference adaptive position control system for ultrasonic motor

The model reference adaptive position control system of the ultrasonic motor in this embodiment is used to output a unit of actual position value y _p according to the position command y _r of the ultrasonic motor; it is used to output a position reference value according to the position command y _r of the ultrasonic motor The unit of y _m ; used to output a unit of reference error e ₁ according to the actual position value y _p and the position reference value y _m , the reference error e ₁ is the difference between the position reference value y _m and the actual position value y _p ; used for A unit for adjusting the actual position value y _p according to the reference error e ₁ ; it also includes a unit for differentially obtaining the speed reference value n _m corresponding to the position reference value y _m according to the position reference value y _m ; used for when the speed reference value When n _m is greater than the actual maximum speed N of the ultrasonic motor, the position reference value y _m is replaced by the corresponding position reference value y _m when the speed reference value n _m is not greater than the actual maximum speed N of the ultrasonic motor.

Each of the above units is a functional module corresponding to each step in the above method embodiment. The method of the present invention runs in the corresponding control system unit, and all or part of the processes in the method embodiments are completed through computer programs or computer programs in cooperation with hardware. The system embodiment is a functional module framework corresponding to the method embodiment.

Claims (8)

1. the model reference adaptive position control method of supersonic motor, including

Position command (y according to supersonic motor_r) one actual position value (y of output_p)；

Position command (y according to supersonic motor_r) one reference by location value (y of output_m)；

According to actual position value (y_p) and reference by location value (y_m), export a reference error (e₁), described reference error (e₁) it is Reference by location value (y_m) and actual position value (y_p) difference；

According to reference error (e₁) regulation actual position value (y_p)；

It is characterized in that: also include according to described reference by location value (y_m), try to achieve reference by location value (y as differential_m) corresponding rotating speed Reference value (n_m)；As described speed reference (n_m) more than actual maximum (top) speed (N) of supersonic motor time, by reference by location value (y_m) with speed reference (n_m) corresponding reference by location value (y when being not more than actual maximum (top) speed (N) of supersonic motor_m) generation Replace.

Model reference adaptive position control method the most according to claim 1, it is characterised in that: the mould of supersonic motor The step response curve of type reference adaptive position output includes three regions successively, respectively starts low regime, rotating speed rising District and rotating speed decline district, wherein start low regime and the speed reference (n in rotating speed decline district_m) it is not more than supersonic motor reality Maximum (top) speed (N), the speed reference (n of rotating speed rising area_m) more than the actual maximum (top) speed (N) of supersonic motor.

Model reference adaptive position control method the most according to claim 2, it is characterised in that: it is additionally included under rotating speed Fall district is to position reference value (y_m) carry out linear interpolation:

If interpolation section is [k1, N], the sampling time is that Ts, y (k) and y (k+1) represent that k moment and k+1 moment are with reference to mould respectively The reference by location value of type output, T (k) and T (k+1) represents k moment and the time point in k+1 moment, interpolation point (x, y) table respectively Show, and have x=T (k)+a*Ts, a be interpolation interval, then interpolation expressions is represented by:

$\begin{array}{c}y=y\left(k\right)+\frac{y(k+1)-y\left(k\right)}{T(k+1)-T\left(k\right)}\left(T\right(k)+a*Ts)\\ =y\left(k\right)+y(k+1)-y\left(k\right)*(k+a)\end{array}$

In formula, as the position command (y of supersonic motor_r) less than 360 ° time, 0 < a < 1；Position command (y when supersonic motor_r) During equal to 360 °, a=1；Position command (y when supersonic motor_r) more than 360 ° time, a > 1.

Model reference adaptive position control method the most according to claim 1, it is characterised in that: use supersonic motor Driving voltage frequency is regulated variable.

5. the model reference adaptive position control system of supersonic motor, including

For the position command (y according to supersonic motor_r) one actual position value (y of output_p) unit；

For the position command (y according to supersonic motor_r) one reference by location value (y of output_m) unit；

For according to actual position value (y_p) and reference by location value (y_m), export a reference error (e₁) unit, described reference Error (e₁) it is reference by location value (y_m) and actual position value (y_p) difference；

For according to reference error (e₁) regulation actual position value (y_p) unit；

It is characterized in that: also include for according to described reference by location value (y_m), try to achieve reference by location value (y as differential_m) corresponding Speed reference (n_m) unit；For as described speed reference (n_m) more than the actual maximum (top) speed (N) of supersonic motor Time, by reference by location value (y_m) with speed reference (n_m) corresponding position when being not more than actual maximum (top) speed (N) of supersonic motor Put reference value (y_m) unit that replaces.

Model reference adaptive position control system the most according to claim 5, it is characterised in that: the mould of supersonic motor The step response curve of type reference adaptive position output includes three regions successively, respectively starts low regime, rotating speed rising District and rotating speed decline district, wherein start low regime and the speed reference (n in rotating speed decline district_m) it is not more than supersonic motor reality Maximum (top) speed (N), the speed reference (n of rotating speed rising area_m) more than the actual maximum (top) speed (N) of supersonic motor.

Model reference adaptive position control system the most according to claim 6, it is characterised in that: also include for turning Speed declines district to position reference value (y_m) carry out the unit of linear interpolation:

If interpolation section is [k1, N], the sampling time is that Ts, y (k) and y (k+1) represent that k moment and k+1 moment are with reference to mould respectively The reference by location value of type output, T (k) and T (k+1) represents k moment and the time point in k+1 moment, interpolation point (x, y) table respectively Show, and have x=T (k)+a*Ts, a be interpolation interval, then interpolation expressions is represented by:

$\begin{array}{c}y=y\left(k\right)+\frac{y(k+1)-y\left(k\right)}{T(k+1)-T\left(k\right)}\left(T\right(k)+a*Ts)\\ =y\left(k\right)+y(k+1)-y\left(k\right)*(k+a)\end{array}$

In formula, as the position command (y of supersonic motor_r) less than 360 ° time, 0 < a < 1；Position command (y when supersonic motor_r) During equal to 360 °, a=1；Position command (y when supersonic motor_r) more than 360 ° time, a > 1.

Model reference adaptive position control system the most according to claim 5, it is characterised in that: use supersonic motor Driving voltage frequency is regulated variable.