CN1323486C - Servo controller for scanning in constant speed - Google Patents

Abstract

The invention belongs to the technical field of control, and is a constant-speed scanning servo controller driven by a DC torque motor. Including power driver, current regulator, precision full-wave rectifier, speed setter, frequency setting module, power supply, direction start controller. The output of the speed setter is connected to the given input terminal of the current regulator; the speed signal given by the tachometer is input to the precision full-wave rectifier, and the output of the precision full-wave rectifier is connected to the feedback input terminal of the current regulator; the frequency setting module 5 The output of the current regulator is connected to the frequency input terminal of the current regulator; the direction and starter 7 are connected to the direction input terminal and the starting terminal of the current regulator; the two control output terminals of the current regulator are connected to the two input terminals of the power driver; the power supply is connected to The power input terminal of the power driver. The invention satisfies the requirement of the speed stability of constant speed scanning by controlling the frequency of the current regulator. The scanning speed is controlled by adjusting the potentiometer, which is convenient for debugging and low in cost.

Description

Isokinetic scanning servo controller

technical field

The invention belongs to the technical field of control, and relates to the scanning servo control of a DC torque motor, in particular to a constant-speed scanning servo controller driven by a DC torque motor.

Background technique

In the control constant speed scanning system, the speed stability is generally required to be high, and the DC torque motor is generally used to drive, the tachometer is used as speed feedback, and the closed-loop mode controlled by the microprocessor is used. The speed voltage fed back by the tachometer is sent to the microprocessor after A/D conversion. After the speed adjustment is completed by the microprocessor, the power drive part is controlled through digital output or analog output through D/A conversion. This device has complex structure, high cost, poor debugging and maintainability.

Contents of the invention

In view of the above problems, the present invention combines a full-bridge power driver, a current regulator and a precision full-wave rectifier, together with a simple peripheral circuit, to realize a bidirectional constant-speed scanning function within a specified angle range, and the purpose is to provide a constant-speed scanning servo controller.

The structural block diagram of the present invention is shown in Figure 1.

The invention includes a power driver 1, a current regulator 2, a precision full-wave rectifier 3, a speed setter 4, a frequency setting module 5, a power source 6, and a direction start controller 7.

The given speed signal of the present invention is given by the speed setter 4, and the speed setter 4 is an adjustable potentiometer, and the speed can be achieved by adjusting the potentiometer as required. The output of the speed setter 4 is connected to the given input terminal of the current regulator 2; the power supply 6 supplies power to the power driver 1; the speed signal given by the tachometer is input to the precision full-wave rectifier 3, and is rectified by the precision full-wave rectifier 3 . The output of the precision full-wave rectifier 3 is connected to the feedback input terminal of the current regulator 2 , and the output of the frequency setting module 5 is connected to the frequency input terminal of the current regulator 2 . The direction of the present invention and the signal of the starter 7 are externally input and connected to the direction input terminal and the starting terminal of the current regulator 2 . The two control output terminals of the current regulator 2 are connected to the two input terminals of the power driver 1 to control the output of the power driver 1 . The power source 6 supplies power to the power driver 1 and is connected to the power input terminal of the power driver 1 .

The control logic principle of the present invention and the connection relationship between the current regulator 2 and other devices are shown in FIG. 2 .

Three AND gates, RS flip-flops, comparators and 555 timers are integrated inside the current regulator 2. The speed given device 4 is an adjustable potentiometer, and its output voltage represents the size of the given speed. The output voltage of the speed setter 4 is connected to one end of the comparator of the current regulator 2, and the other end of the comparator is connected to the output of the precision full-wave rectifier 3, and the output of the comparator is connected to the R reset of the RS flip-flop inside the current regulator 2 end. The frequency setting module 5 is generated by RC oscillation, connected to the oscillation frequency input terminal of the 555 timer of the current regulator 2, and the frequency generated by the 555 timer is connected to the RS flip-flop through the external frequency input pin of the current regulator 2 S set terminal. The two direction and start signals of the direction and start controller 7 are respectively connected to the direction input terminal and the start terminal of the current regulator 2, and are connected together with the Q terminal output of the RS flip-flop in the current regulator 2 inside the current regulator 2 To the input of the three-AND gate, the outputs of the two three-AND gates are respectively connected to the two drive signal input terminals of the power driver 1 as the control signal of the power driver 1 .

The tachometer signal voltage of the constant-speed scanning system is positive or negative, and must be rectified when entering the comparator input of the current regulator 2, so that the tachometer voltage becomes a positive value, which is the core of realizing constant-speed bidirectional scanning. The rectification of the tachometer signal is done by a precision full-wave rectifier 3.

The structure of the precision full-wave rectifier 3 of the present invention and the connection relationship with other devices are shown in FIG. 3 .

The precision full-wave rectifier 3 consists of two operational amplifiers, two resistors and two diodes. One of the two operational amplifiers is operational amplifier A, and the other is operational amplifier B. The positive input terminal of the operational amplifier A is directly connected to the tachometer, and the signal voltage signal is input by the tachometer; the negative input terminal is connected to the rectifier output terminal. The output of the operational amplifier A is connected to the rectified output terminal through the positive diode D6. The negative input terminal of the operational amplifier B is connected to the tachometer through the resistor R1, and the voltage signal is input from the tachometer, and connected to the rectified output terminal through the resistor R2. The positive input terminal is connected to 5V ground. The output of the operational amplifier B is connected to the rectified output terminal through the positive diode D5. When the voltage of the tachometer is greater than 0V, the output of the operational amplifier B is negative, and the diode D5 reverse-biases to block its output; the output of the operational amplifier A is positive, and this non-inverting amplifier outputs the voltage of the tachometer at unity gain. When the tachometer voltage is less than 0V, the output of the operational amplifier B is positive, and the diode D5 is positively connected. The operational amplifier B works in the reverse amplification state, and the gain is R2 to R1. If the resistance values of R2 and R1 are the same, it is unity gain; operation The output of amplifier A is negative, and diode D6 is reverse-biased to block its output.

The working process of the present invention is that the voltage of the tachometer is rectified by the precision full-wave rectifier 3 and enters the comparator for comparison with the voltage of the speed setter 4. If the voltage of the tachometer is less than the voltage of the speed setter 4, the output of the comparator is 0. The reset terminal of the RS flip-flop is not set; the output of the Q terminal of the RS flip-flop is set by the signal of the set terminal, and remains until the reset terminal of the RS flip-flop is set, and the output of the comparator is 1. The output of the Q terminal of the RS flip-flop, the direction signal and the start signal are phase-ANDed to control the control terminal of the full-bridge driver.

The start-up and direction control of the constant-speed scan in the present invention are controlled by an external input, and the speed stability requirement of the constant-speed scan is met by controlling the frequency of the current regulator. The scanning speed is controlled by adjusting the potentiometer, which is convenient for debugging and low in cost.

Description of drawings

Fig. 1 is a structural schematic diagram of the present invention. In the figure, 1 is the power driver, 2 is the current regulator, 3 is the precision full-wave rectifier, 4 is the speed setting device, 5 is the frequency setting module, 6 is the power supply, 7 is the direction and starting controller.

FIG. 2 is a schematic diagram of the control logic principle and the connection relationship between the current regulator 2 and other devices.

FIG. 3 is a diagram showing the structure of the precision full-wave rectifier 3 and its connections with other devices. A and B in the figure are operational amplifiers.

Detailed ways

The specific embodiment will be described with reference to the accompanying drawings.

As shown in Figures 1 and 2, the power driver 1 is a full-bridge driver, the present invention uses a SGS L6203 full-bridge driver, and the current regulator 2 uses a SGS L6506.

As shown in Figure 3, the operational amplifiers A and B in the precision full-wave rectifier 3 use TL062. The precision full-wave rectifier 3 integrates two operational amplifiers, that is, operational amplifiers A and B. The 8 pins of the operational amplifiers A and B are connected to the positive power supply, and the 4 pins are connected to the power ground. The resistors R2 and R1 have the same resistance value, which is 10KΩ in the present invention. Diodes D5 and D6 in precision full-wave rectifier 3 use In4007. The positive input terminal 3 of the operational amplifier A is directly connected to the voltage signal of the speedometer, and the negative input terminal 2 is connected to the rectification output terminal; the output terminal 1 of the operational amplifier A is connected to the rectification output terminal through the positive diode D6. The negative input terminal 6 of the operational amplifier B is connected to the voltage signal of the tachometer through the resistor R1, connected to the rectified output terminal through the resistor R2, and the positive input terminal 5 is connected to the 5V ground; the output 7 pin of the operational amplifier B is connected to the positive diode D5 and rectified connected to the output.

The frequency of the frequency setting module 5 is f=1/0.69RC, wherein R is a resistor, and C is a capacitor. Adjust R and C to obtain a suitable frequency. In the present invention, the resistor R is 22kΩ, the capacitor C is 3.3nf, and the frequency f is 20kHz. Connect the frequency output signal of the frequency setting module 5 to the trigger frequency input terminal of the current regulator 2 .

The two direction and start signals of the direction and start controller 7 are respectively connected to the direction input end and the start end of the current regulator 2; when the start end input is 1, the system works, when the start end input is 0, the system does not work; the two direction signal 1, 0 controls one direction, 0, 1 controls the opposite direction.

The two control output terminals of the current regulator 2 are connected to the two input terminals of the power driver 1 . Connect the speed given voltage signal to the speed given end of the current regulator 2. When the invention works, the function of speed regulation is achieved by changing the potentiometer to adjust the speed given voltage.

The invention has been successfully applied to a certain CCD scanning turntable. High speed stability, can realize two-way constant speed scanning function.

Claims (5)

1, a kind of servo controller for scanning in constant speed is characterized in that comprising analog line driver (1), current regulator (2), accurate full-wave rectifier (3), speed setter (4), frequency setting module (5), power power-supply (6), direction and starter controller (7); The output of speed setter (4) is connected to the given input of current regulator (2); The rate signal that tachometer provides is input to accurate full-wave rectifier (3) and carries out rectification, and accurate full-wave rectifier (3) output connects the feedback input end of current regulator (2); The output of frequency setting module (5) connects the frequency input of current regulator (2); The signal of direction and starter controller (7) is imported by the outside, is connected to current regulator (2) direction input and starting end; The output of the two-way power controlling driver (1) of current regulator (2) is linked analog line driver (1) two-way input; Power power-supply (6) is linked the power input of analog line driver (1).

2, servo controller for scanning in constant speed according to claim 1 is characterized in that speed setter (4) is a potentiometer according to adjustable-speed; Current regulator (2) inside be integrated with three with door, rest-set flip-flop, comparator and 555 timers; Accurate full-wave rectifier (3) is made up of two-way amplifier, two resistance and two diodes, and a road of two-way amplifier is an operational amplifier A, and another road is operational amplifier B; Speed setter (4) output voltage is linked an end of the comparator of current regulator (2), the output of the accurate full-wave rectifier of another termination (3) of comparator; The output of comparator is at the inner R reset terminal that connects rest-set flip-flop of current regulator (2), the output of Q end, initiating signal and the direction signal of rest-set flip-flop together be connected in current regulator 2 inside three with the input of door; The frequency setting module (5) that produces frequency of oscillation by RC is linked the frequency of oscillation input of 555 timers of current regulator (2), and the frequency that 555 timers produce is linked the S set end of rest-set flip-flop by the foreign frequency input pin of current regulator (2); The S set end of rest-set flip-flop; The two-way direction of direction and starter controller (7) and initiating signal are connected respectively to current regulator (2) direction input and starting end, and with current regulator (2) in rest-set flip-flop Q end output current regulator (2) inner together be connected to three with the input of door, the two-way driving signal input of analog line driver (1) is linked in the output of two-way three and door respectively, as the control signal of analog line driver (1); The positive input terminal of the operational amplifier A in the accurate full-wave rectifier (3) tachometer direct and by input voltage signal links to each other, and negative input end is linked rectification output end, and the output of operational amplifier A is linked rectification output end through just connecing second diode (D6); The negative input end of operational amplifier B in the accurate full-wave rectifier (3) links to each other with tachometer by input voltage signal by first resistance (R1), and link to each other with rectification output end by resistance second resistance (R2), positive input termination 5V ground, output links to each other with rectification output end through just connecing first diode (D5).

3, servo controller for scanning in constant speed according to claim 2 is characterized in that analog line driver (1) is the L6203 full bridge driver, and current regulator (2) is L6506; Operational amplifier A and B in the accurate full-wave rectifier (3) are TL062, and first diode (D5) and second diode (D6) are selected In4007 for use, and first resistance (R1) is identical with second resistance (R2) resistance.

4, servo controller for scanning in constant speed according to claim 3, it is characterized in that operational amplifier A in the accurate full-wave rectifier (3) and 8 pin of B connect positive supply, 4 pin connect power supply ground, positive input terminal 3 pin directly link to each other with the tachometer voltage signal, negative input end 2 pin are linked rectification output end, export 1 pin and link rectification output end through just connecing second diode (D6); Negative input end 6 pin of operational amplifier B in the accurate full-wave rectifier (3) link to each other with the tachometer voltage signal by first resistance (R1), (R2) links to each other with rectification output end by second resistance, positive input terminal 5 pin connect 5V ground, export 7 pin and link to each other with rectification output end through just connecing first diode (D5).

5, servo controller for scanning in constant speed according to claim 2 is characterized in that the circuit of accurate full-wave rectifier (3) is input to the output delay time minimum and positive and negative input is had the same delay time; When tachometer voltage during greater than 0V, the output of operational amplifier B is born, anti-its output of blocking-up partially of first diode (D5), the output of operational amplifier A is positive, this in the same way amplifier tachometer voltage by unit gain output; When tachometer voltage during less than 0V, the output of operational amplifier B is positive, first diode (D5) just connects, operational amplifier B is operated in reverse magnifying state, gain be second resistance (R2) than first resistance (R1), get second resistance (R2), first resistance (R1) resistance is identical, then is unit gain, the output of operational amplifier A is born, its output of the anti-blocking-up partially of second diode (D6).