Double-linear-motor driving pair for optical adjusting frame and control method

Abstract

The invention provides a double-linear-motor driving pair for an optical adjusting frame and a control method.The driving pair comprises tubular linear motors distributed on the two sides of a truss, stators of the tubular linear motors are fixed to the truss, one end of a rotor of each tubular linear motor penetrates through the corresponding stator and is connected with the adjusting frame through a universal ball head, and the other end of the rotor of each tubular linear motor penetrates through the corresponding truss; a displacement sensor is mounted on the stator side of the tubular linear motor, current is introduced into a stator of the tubular linear motor to generate a stator magnetic field, and the rotor reciprocates back and forth under the action of the stator magnetic field to drive the adjusting frame to pitch and deflect. According to the method, the influence caused by backlash errors and position synchronization differences can be eliminated on the premise of ensuring the resolution.

Description

Technical Field

[0001] The invention relates to the field of adjustment of an optical adjustment frame, and in particular to a dual linear motor driving pair and a control method for the optical adjustment frame. Background Art

[0002] Traditional optical equipment uses manual adjustment mechanical devices to adjust the two-dimensional angle of the optical frame in space to adjust the direction of the optical path. This adjustment method cannot achieve precise adjustment of the optical path, and the operation is cumbersome and depends on the operator's experience. With the development of electric drive, motor drive is used to replace manual adjustment.

[0003] Patent CN104180133A provides a precision electric adjustment frame structure, in which a stepper motor is connected to a planetary gear reducer, the reducer output shaft is connected to an elastic bellows coupling, and the coupling output end is connected to a precision screw, and the adjustment of the optical frame is achieved by moving the precision screw.

[0004] The above patent uses a stepper motor drive, which is an open-loop control. Due to the existence of the gap between the screw and reducer and the processing error, the position synchronization performance of the drive pairs on both sides will be poor. In addition, although the addition of a bellows coupling can effectively reduce the return error and maintain stability, it still cannot eliminate it. Finally, the assembly process of the series structure of stepper motor, planetary reducer, elastic bellows coupling and screw is relatively complicated, and the consistency of the structural assembly is poor. Summary of the invention

[0005] Aiming at the backlash error and position synchronization problems existing in the existing stepper motor driving mode, the present invention provides a dual linear motor driving pair and control method for an optical adjustment frame, which can eliminate the influence of backlash error and position synchronization difference while ensuring the resolution.

[0006] To achieve the above object, the embodiments of the present invention adopt the following technical solutions:

[0007] In a first aspect, the present invention provides a dual linear motor drive pair for an optical adjustment frame, comprising tubular linear motors distributed on both sides of a truss, wherein the stator of the tubular linear motor is fixed on the truss, one end of the mover of the tubular linear motor passes through the stator and is connected to the adjustment frame through a universal ball head, a displacement sensor is installed on the stator side of the tubular linear motor, current is passed through the stator of the tubular linear motor to generate a stator magnetic field, and the mover performs reciprocating motion back and forth under the action of the stator magnetic field, driving the adjustment frame to perform pitch and yaw motions.

[0008] Furthermore, the end of the mover of the tubular linear motor is connected to the universal ball head through an interference fit.

[0009] Furthermore, the displacement sensor is a grating ruler.

[0010] In a second aspect, the present invention provides a control method for a dual linear motor drive pair for an optical adjustment frame, and designs a position planning control mode of the linear motor drive pair. Each linear motor drive pair uses a closed-loop control circuit to make the position of the linear motor drive pair reach the command position according to the planning control mode.

[0011] Furthermore, the position planning control mode is: given a relative displacement, the speed is accelerated to a set speed limit according to a set acceleration, and then controlled according to the speed. When approaching the end position, it is decelerated to zero according to a set deceleration, and reaches the command position within the planned time.

[0012] Furthermore, the closed-loop control circuit uses the real-time position signal measured by the displacement sensor as a feedback signal to form a closed loop.

[0013] Furthermore, a position synchronization control loop is added to the position loop of the two closed-loop control loops, the set value of the synchronization control loop is 0, and 1 / 2 of the position difference of the real-time position signals measured by the two displacement sensors is used as the feedback signal of the synchronization control loop. The difference between the set value and the feedback signal is output through the position difference regulator as a position given compensation, which is input into each closed-loop control loop respectively, and the position synchronization of the two linear motor drive pairs is controlled through the position synchronization control loop.

[0014] Furthermore, if the output signal of the position difference regulator is positive, the output signal is used as the position given compensation of the smaller of the two linear motor drive positions, and after being inverted, it is used as the position given compensation of the larger of the two positions; if the output of the position difference regulator is negative, it is used as the position given compensation of the larger of the two positions, and after being inverted, it is used as the position given compensation of the smaller of the two positions.

[0015] Compared with the prior art, the present invention has the following beneficial effects:

[0016] (1) The dual linear motor drive method used for the optical adjustment frame adopted by the present invention is simpler in structure and has better assembly processability than the traditional stepper motor drive method, and directly eliminates the backlash error;

[0017] (2) The position planning control mode adopted by the present invention can effectively reduce position overshoot and provide adjustment resolution;

[0018] (3) The dual linear motor position synchronization closed-loop control strategy proposed in the present invention improves the consistency of the swing of the adjustment frame, reduces the structural force dispute caused by the asynchronous drive of the left and right sides, and indirectly increases the service life of the product;

[0019] (4) The position synchronization closed-loop control strategy proposed in the present invention can be extended to the field of dual-motor or multi-motor coordinated control for application. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 The left and right linear motor drive pairs in the optical adjustment frame provided by the embodiment of the present invention;

[0021] Figure 2 A speed-time curve diagram of a position planning control mode provided by an embodiment of the present invention;

[0022] Figure 3 A block diagram of the synchronous control of the left and right linear motor drive positions provided by an embodiment of the present invention;

[0023] Figure 4 A comparison chart of simulation results of linear motor position synchronization control and stepper motor + screw open-loop control provided in an embodiment of the present invention. DETAILED DESCRIPTION

[0024] Example 1

[0025] like Figure 1 As shown, a dual linear motor drive pair for an optical adjustment frame includes two tubular linear motors, which are located on the left and right sides of a truss 1. The tubular linear motors are composed of a first linear motor stator 3 and a second linear motor stator 7, which are respectively fixed on both sides of the truss, a first linear motor mover 2 and a second linear motor mover 8, a first universal ball head 4 and a second universal ball head 6. Current is passed through the first linear motor stator 3 and the second linear motor stator 7 to generate a stator magnetic field, and the movers reciprocate back and forth under the action of the stator magnetic field, thereby driving the swing of the adjustment frame 5. When the first linear motor movers 2 and the second linear motor movers 8 on the left and right sides move forward or backward synchronously, the adjustment frame 5 performs a pitching motion; when the first linear motor movers 2 and the second linear motor movers 8 on the left and right sides move forward and backward, the adjustment frame 5 performs a deflection motion, thereby realizing a two-dimensional angle adjustment of the adjustment frame 5.

[0026] The grating ruler is installed on each stator side to measure the displacement of the mover;

[0027] The universal ball joint is installed at the ends of the shafts of the first linear motor mover 2 and the second linear motor mover 8 by interference fit.

[0028] Example 2

[0029] This embodiment provides a linear motor driven position planning control mode. Given a relative displacement, the speed is accelerated to the planned speed limit according to a certain planned acceleration, and then controlled according to the speed. When approaching the end position, it is decelerated to zero according to another planned acceleration and reaches the command position. Figure 2 The speed-time curve shown in the figure shows that the command position is reached within the specified time t3 according to the given relative displacement S, the planned acceleration is a1, the planned deceleration is a2, and the command position is reached within the specified time t3. This position planning control method, when a certain absolute displacement is traveled within the specified time, corresponds to different speed limits, which effectively reduces the overshoot caused by the speed step response and improves the position control accuracy.

[0030] Example 3

[0031] An embodiment of the present invention provides a loop control method, including left and right linear motor drive pair position synchronization control, adding position difference control, also known as Δθ*=0 control, and the output of the position difference regulator is used as a given negative compensation to the larger position of the two and a positive compensation to the smaller position, and the position synchronization of the two drive pairs is ensured through closed-loop control.

[0032] like Figure 3 The above is a block diagram of the position synchronization control of the left and right linear motor drive pairs of the optical adjustment frame. In the figure, the inverter provides current for the motor drive pair. Each motor drive pair adopts closed-loop control, and the real-time position signal measured by each grating ruler is used as the feedback signal of the closed-loop control loop. * The error, the position regulator calculates the predicted speed, and the speed calculated based on the actual value is input to the speed regulator. The difference between the output of the speed regulator and the detected value of the actual current is used as the input of the current regulator. The current regulator outputs the predicted current signal, which is input into the PWM control, and then controls the inverter to obtain the control signal of the motor drive pair. The control of the inverter belongs to the well-known part in the field and will not be elaborated in detail here. At the same time, the drive pairs on both sides of the present invention receive the same position instruction, and the feedback position information is the real-time position measured by each grating ruler. A position synchronization control loop is added to the position loop of the linear motors on both sides. 1 / 2 of the feedback position difference on both sides is the loop feedback signal, the given signal is 0, and the output obtained by the regulator is positive, then it is used as the position given compensation of the smaller position of the two, and after being inverted, it is used as the position given compensation of the larger position of the two; if the obtained output is negative, it is used as the position given compensation of the larger position of the two, and after being inverted, it is used as the position given compensation of the smaller position of the two. The position synchronization of both sides is improved through closed-loop regulation.

[0033] like Figure 4 As stated, Figure 4 (a) is the simulation result of the optical adjustment frame deflection motion under the open-loop control of the stepper motor. Figure 4(b) is the simulation result of the deflection motion of the optical adjustment frame under the linear motor position synchronization control. The horizontal coordinate represents the deflection displacement of the reflected light spot, and the vertical coordinate represents the pitch displacement. When performing the deflection action, the vertical coordinate fluctuation range on the left side of the figure is 1661um-1699um, and the vertical coordinate fluctuation range on the right side of the figure is 1685um-1689um. This shows that the linear motor position synchronization control method is better.

[0034] The present invention realizes precise adjustment of the optical adjustment frame by applying the linear motor drive and its position synchronization control algorithm to the optical adjustment frame. The dual linear motor drive pair and position synchronization control method for the optical adjustment frame proposed by the present invention replace the traditional stepper motor drive mode, realize the position synchronization control of the optical adjustment frame; under the premise of ensuring the position control accuracy, the return error is eliminated. In addition, the linear motor drive pair structure is simpler, easy to assemble, and the process design is optimized.

[0035] The preferred specific implementation modes and embodiments of the present invention are described in detail above in conjunction with the accompanying drawings, but the present invention is not limited to the above implementation modes and embodiments, and various changes can be made within the knowledge scope of those skilled in the art without departing from the concept of the present invention.

Claims

1. A dual linear motor drive pair for an optical adjustment frame, characterized in that: It comprises tubular linear motors distributed on both sides of a truss, wherein the stator of the tubular linear motor is fixed on the truss, one end of the mover of the tubular linear motor penetrates the stator and is connected to an adjustment frame through a universal ball head, a displacement sensor is installed on the stator side of the tubular linear motor, current is passed through the stator of the tubular linear motor to generate a stator magnetic field, and the mover performs a back-and-forth reciprocating motion under the action of the stator magnetic field to drive the swing of the adjustment frame.

2. A dual linear motor drive pair for an optical adjustment frame according to claim 1, characterized in that: The end of the mover of the tubular linear motor is connected to the universal ball head through interference fit.

3. The dual linear motor drive pair for an optical adjustment frame according to claim 1, characterized in that: The displacement sensor is a grating ruler.

4. A control method for a dual linear motor drive pair for an optical adjustment frame, characterized in that: Design a position planning control mode for the linear motor drive pair as described in any one of claims 1-3, and each linear motor drive pair uses a closed-loop control circuit to make the position of the linear motor drive pair reach the command position according to the planning control mode.

5. The control method of the dual linear motor drive pair according to claim 4, characterized in that: The position planning control mode is: given a relative displacement, the speed is accelerated to a set speed limit according to a set acceleration, and then controlled according to the speed. When approaching the end position, it is decelerated to zero according to a set deceleration, and reaches the command position within the planned time.

6. The control method of the dual linear motor drive pair according to claim 4, characterized in that: The closed-loop control loop uses the real-time position signal measured by the displacement sensor as a feedback signal to form a closed loop.

7. The control method of the dual linear motor drive pair according to claim 4, characterized in that: A position synchronization control loop is added to the position loop of the two closed-loop control loops. The setting value of the synchronization control loop is 0. 1 / 2 of the position difference of the real-time position signals measured by the two displacement sensors is used as the feedback signal of the synchronization control loop. The difference between the setting value and the feedback signal is output through the position difference regulator as a position given compensation and input into each closed-loop control loop respectively. The position synchronization of the two linear motor drive pairs is controlled through the position synchronization control loop.

8. The control method of the dual linear motor drive pair according to claim 7, characterized in that: If the output signal of the position difference regulator is positive, the output signal is used as the position given compensation of the smaller position of the two linear motor drive pairs, and after being inverted, it is used as the position given compensation of the larger position of the two; if the output of the position difference regulator is negative, it is used as the position given compensation of the larger position of the two, and after being inverted, it is used as the position given compensation of the smaller position of the two.

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