Servo valve control system and robot

Abstract

The present disclosure provides a servo valve control system and a robot. The system comprises a controller and a plurality of voltage output digital-to-analog converters, the chip select signal input ends of the plurality of voltage output digital-to-analog converters are connected to the same chip select signal output end of the controller, the clock signal input ends of the plurality of voltage output digital-to-analog converters are connected to the same clock signal output end of the controller, the serial data input ends and the serial data output ends of the controller and the plurality of voltage output digital-to-analog converters are connected in sequence in a ring, the controller is configured to output the digital signals required by the plurality of voltage output digital-to-analog converters in sequence through the serial data output end thereof, and the plurality of voltage output digital-to-analog converters are configured to transmit the digital signals received thereby to the serial data output ends thereof and convert the digital signals received thereby within a set period into analog voltage signals to drive corresponding servo valves. The system saves the number of ports and wiring space.

Description

Technical Field

[0001] This disclosure belongs to the field of robot control technology, specifically relating to a servo valve control system and a robot. Background Technology

[0002] This section is intended to provide background or context for the embodiments set forth in the claims. The description herein is not an admission that it is prior art simply because it is included in this section.

[0003] In the deep-sea environment, robotic arms operate under high pressure. The hydraulic robotic arm control system must be able to automatically balance and compensate for environmental pressure, and match external operational characteristics over a wide range. Therefore, hydraulically driven multi-jointed robotic arms have become the primary operational tool for deep-sea submersibles. However, maintaining optimal performance of the hydraulic robotic arm hinges on effective control of the hydraulic servo valves. This requires both real-time actuation of the multi-channel servo valves and consideration of the control system's compatibility. Summary of the Invention

[0004] This disclosure provides a servo valve control system and a robot.

[0005] This disclosure adopts the following technical solution: a servo valve control system, comprising: a controller and multiple voltage output digital-to-analog converters (DACs), wherein the chip select signal input terminals of the multiple voltage output DACs are all connected to the same chip select signal output terminal of the controller, and the clock signal input terminals of the multiple voltage output DACs are all connected to the same clock signal output terminal of the controller. The serial data input terminals and serial data output terminals of the controller and the multiple voltage output DACs are sequentially connected end-to-end to form a loop. The controller is configured to sequentially output the digital signals required by the multiple voltage output DACs through its serial data output terminal. The multiple voltage output DACs are configured to transmit the received digital signals to their serial data output terminals and convert the digital signals received within a set time period into analog voltage signals to drive the corresponding servo valves. The multiple voltage output DACs are used to be connected one-to-one with the servo valves.

[0006] In some embodiments, the system further includes a sensor, a voltage-to-current converter, and a current-input analog-to-digital converter. The sensor outputs an analog voltage signal at its analog voltage signal output terminal. The voltage-to-current converter converts the analog voltage signal into an analog current signal. The current-input analog-to-digital converter is used to convert the analog current signal into a digital signal. The voltage-to-current converter includes:

[0007] The system comprises a first resistor, a second resistor, a sixth resistor, a first operational amplifier, and a first transistor. The first resistor is connected in series between the reference voltage terminal and the non-inverting input terminal of the first operational amplifier. The second resistor is connected in series between the analog voltage signal output terminal and the non-inverting input terminal of the first operational amplifier. The output terminal of the first operational amplifier is electrically connected to the base of the first transistor. The two current detection terminals of the current input analog-to-digital converter are connected in series between the first power supply terminal and the collector of the first transistor. The emitter of the first transistor is electrically connected to the inverting input terminal of the first operational amplifier. The sixth resistor is connected between the emitter of the first transistor and the second power supply terminal.

[0008] In some embodiments, the voltage-to-current converter further includes: a third resistor, wherein the two current detection terminals of the current input analog-to-digital converter are connected in series between the first power supply terminal and the collector of the first transistor via the third resistor; and / or,

[0009] The voltage-to-current converter further includes: a fourth resistor, the first end of which is connected to the output terminal of the first operational amplifier, and the second end of which is connected to the base of the first transistor; and / or,

[0010] The voltage-to-current converter further includes a fifth resistor, the first end of which is connected to the inverting input of the first operational amplifier, and the second end of which is connected to the emitter of the first transistor.

[0011] In some embodiments, the resistance values ​​of the first resistor and the second resistor are equal.

[0012] In some embodiments, an AC / DC voltage conversion circuit is further included to convert the external AC power supply voltage into a DC power supply voltage to power the controller. The AC / DC voltage conversion circuit includes: a second operational amplifier, a third operational amplifier, an RS flip-flop, a second transistor, a seventh resistor, a transformer primary, a transformer secondary, and an AC-to-DC conversion circuit. The output terminal of the DC-to-AC conversion circuit serves as the power output terminal.

[0013] The non-inverting input of the second operational amplifier receives a reference voltage signal, its inverting input is connected to the power supply output, and its output is connected to the non-inverting input of the third operational amplifier.

[0014] The inverting input terminal of the third operational amplifier is connected to the emitter of the second transistor, and the output terminal of the third operational amplifier is connected to the R terminal of the RS flip-flop.

[0015] The S terminal of the RS flip-flop receives a clock signal, and the Q terminal of the RS flip-flop is connected to the base of the second transistor.

[0016] The seventh resistor is connected between the emitter of the second transistor and the second power supply terminal;

[0017] The primary winding of the transformer is connected between the power input terminal and the collector of the second transistor.

[0018] The primary and secondary windings of the transformer are coupled to form a transformer, and the secondary winding is connected between the second power supply terminal and the input terminal of the AC-to-DC conversion circuit.

[0019] In some embodiments, the AC-to-DC converter circuit includes: a first diode, a second diode, an inductor, and a capacitor;

[0020] The anode of the first diode serves as the input terminal of the AC-to-DC converter circuit, the anode of the second diode is connected to the second power supply terminal, the anodes of both the first and second diodes are connected to the first terminal of the inductor, the second terminal of the inductor is connected to the power output terminal, and the capacitor is connected between the power output terminal and the second power supply terminal.

[0021] The present disclosure adopts the following technical solution: a robot, including the above-mentioned servo valve control system.

[0022] The controller and multiple voltage output digital-to-analog converters (DACs) are connected in a daisy-chain configuration. The controller acts as the master device, and the DACs act as slave devices. Multiple DACs are connected in series. A single set of ports on the controller used to control one DAC can be used to control multiple DACs, effectively controlling multiple servo valves. This significantly reduces the number of controller ports, the required wiring space, and the size of the circuit board used in the system. Attached Figure Description

[0023] Figure 1 This is a block diagram of a servo valve control system according to an embodiment of the present disclosure.

[0024] Figure 2 This is a schematic diagram showing the connection relationship between the underwater controller and the servo driver in an embodiment of this disclosure.

[0025] Figure 3 This is a circuit diagram of a voltage-current converter in an embodiment of this disclosure.

[0026] Figure 4 This is a circuit diagram of the AC / DC voltage conversion circuit in an embodiment of this disclosure. Detailed Implementation

[0027] The present disclosure will be further described below with reference to the embodiments shown in the accompanying drawings.

[0028] Figure 1 This is a block diagram of a servo valve control system according to an embodiment of this disclosure. This system is a servo valve control system for an underwater robot. However, the system is not limited to underwater robots. The controller includes, for example, a central processing unit (CPU), a microprocessor unit (MCU), etc. The communication terminal is, for example, a computer, which is connected to the controller via an RS485 bus. The communication terminal can send commands to the controller, which then controls the servo drive according to the commands. An external power supply provides the controller with three power sources: ±12V and two 24V power sources. Sensors can be used to collect environmental parameters. The servo valve control system is typically sealed inside an oil pan. A water inlet sensor is used to detect whether water has entered the oil pan. A proportional valve is used to control the flow rate of oil entering and leaving the oil pan, etc. A temperature sensor collects the ambient temperature.

[0029] Figure 2 This is a schematic diagram showing the connection relationship between the underwater controller and the servo driver in an embodiment of this disclosure. Figure 2 The master device in the SPI Master is Figure 1 The controller in the system. Figure 2 The system consists of three SPI slave devices (specifically, three voltage-output digital-to-analog converters). Figure 1 The servo driver in the system. Combined with... Figure 1 and Figure 2 The servo valve control system provided in this embodiment includes: a controller and multiple voltage output digital-to-analog converters, with chip select signal input terminals for the multiple voltage output digital-to-analog converters. All are connected to the same chip select signal output terminal of the controller. The clock signal input terminals SCLK of multiple voltage output digital-to-analog converters are all connected to the same clock signal output terminal SCLK of the controller. The serial data input terminals SDI, MOSO and serial data output terminals SDO, MOSI of the controller and multiple voltage output digital-to-analog converters are connected end to end in a loop. The controller is configured to output the digital signals required by the multiple voltage output digital-to-analog converters in sequence through its serial data output terminal MOSI. The multiple voltage output digital-to-analog converters are configured to transmit the digital signals they receive to their serial data output terminals SDO and convert the digital signals they receive within a set time period into analog voltage signals to drive the corresponding servo valves (not shown). The multiple voltage output digital-to-analog converters are used to connect one-to-one with the servo valves.

[0030] In some embodiments, the voltage output digital-to-analog converter (DAC) is provided by the AD5754 chip. The analog voltage signal output by the DAC controls the opening degree of the servo valve. The controller uses a daisy-chain configuration to control multiple DACs (equivalent to controlling multiple servo valves). Each DAC uses SPI communication to use the output value of the previous DAC as the input value of the next DAC. A set of serial ports on the controller can control multiple servo valves simultaneously or drive only a specific servo valve. By connecting multiple servo valves using a limited number of signal transmission lines, underwater servo valve operations can be completed efficiently and in real time, without bus contention or congestion.

[0031] The voltage-output digital-to-analog converter (DAC) SPI Slave operates in daisy-chain mode. All voltage-output DACs share the chip select signal output of the controller SPI Slave. The clock signal output terminal SCLK and its corresponding wiring are connected, while the serial data output terminal SDO of the voltage output DAC is connected to the serial data input terminal SDI of the next voltage output DAC. A single 16-bit SPI frame instruction puts all voltage output DACs into daisy-chain mode. In daisy-chain mode, the serial data output terminal SDO is an 8-cycle delayed version of the serial data input terminal SDI signal.

[0032] The controller and multiple voltage output digital-to-analog converters (DACs) are connected in a daisy-chain configuration. The controller acts as the master device, and the DACs act as slave devices. Multiple DACs are connected in series. A single set of ports on the controller used to control one DAC can be used to control multiple DACs, effectively controlling multiple servo valves. This significantly reduces the number of controller ports, the required wiring space, and the size of the circuit board used in the system. Figure 3 This is a circuit diagram of a voltage-current converter in an embodiment of this disclosure.

[0033] Figure 3 This is a circuit diagram of a voltage-to-current converter according to an embodiment of this disclosure. In some embodiments, combined with Figure 1 and Figure 3 The servo valve control system also includes a sensor, a voltage-to-current converter, and a current input analog-to-digital converter. The sensor outputs an analog voltage signal. The voltage-to-current converter converts the analog voltage signal into an analog current signal. The current input analog-to-digital converter (not shown, for example, integrated in the controller) converts the analog current signal into a digital signal. The voltage-to-current converter includes:

[0034] The first resistor R1, the second resistor R2, the third resistor R3, the fourth resistor R4, the fifth resistor R5, the sixth resistor R6, the first operational amplifier A1, and the first NPN transistor B1 are connected in series with the reference voltage terminal V. n A second resistor R2 is connected in series with the non-inverting input of the first operational amplifier A1 at the analog voltage signal output terminal V. i Between the non-inverting input terminal of the first operational amplifier A1 and the output terminal of the first operational amplifier A1, the fourth resistor R4 is connected in series between the output terminal of the first operational amplifier A1 and the base of the first transistor B1. The third resistor R3 and the two current sensing terminals of the current input analog-to-digital converter (equivalent resistance R) are connected in series between the first power supply terminal (providing +12V voltage) and the collector of the first transistor B1. The fifth resistor R5 is connected between the emitter of the first transistor B1 and the inverting input terminal of the first operational amplifier A1. The sixth resistor R6 is connected between the emitter of the first transistor B1 and the second power supply terminal.

[0035] In this embodiment, the second power supply terminal is ground, and the first power supply terminal provides a 12V voltage.

[0036] In other embodiments, the first transistor B1 is a PNP transistor.

[0037] In some embodiments, the resistance values ​​of the first resistor R1 and the second resistor R2 are equal.

[0038] Specifically, the first operational amplifier A1 is an LM324 chip, and the first transistor B1 is a BG9013 chip. Reference voltage terminal V n A bias voltage is provided, and the analog voltage signal output terminal V_i receives the analog voltage signal to be converted. The equivalent resistance R is the input resistance of the current input analog-to-digital converter. The first operational amplifier A1 acts as a comparator, comparing the voltage signal at its non-inverting input terminal with the voltage signal at its inverting input terminal. The comparison result is amplified by the first operational amplifier A1 and then by the first transistor B1. The emitter current Ie of the BG9013 chip acts on the sixth resistor R6 (specifically a potentiometer). According to the properties of the operational amplifier, V- = Ie·Rw = (1+k)Ib·Rw; where V- is the voltage at the inverting input terminal of the first operational amplifier; Ie is the emitter current of the first transistor B1; Rw is the resistance of the sixth resistor; Ib is the base current of the first transistor B1; and k is the amplification factor.

[0039] The current Io flowing through the load R (i.e., the collector current of chip BG9013) is equal to k·Ib. Let R1 = R2, then we have: 0.5*(Vn+Vi)=(V+)=(V-)=(1+k)Ib·Rw=(1+1 / k)Io·Rw.

[0040] Since k >> 1, Io ≈ 0.5(Vn + V i ) / Rw.

[0041] As can be seen from the above analysis, when the bias voltage Vn and the sixth resistor R6 are constant, the magnitude of the output current Io is related to the input voltage Vin, but not to the magnitude of the load resistor R, indicating that the voltage-current converter has good constant current performance.

[0042] Based on the above relationships, for example, to convert a 0-5V voltage signal into a 0-5mA current signal, we can set Vn = 0V and Rw = 1kΩ. If we convert a 0-5V voltage signal into a 1-5mA current signal, we can determine Vn = 1.25V and Rw = 1.25kΩ. Similarly, to convert a 4-20mA current signal into a 1-5mA current signal, we only need to first convert the 4-20mA current signal into a voltage signal, and then determine the parameters Vn and Rw according to the above relationships. Other conversions can be deduced similarly.

[0043] It should be noted that the third resistor R3 serves to limit current. In some embodiments, the third resistor R3 can be omitted. The fifth resistor R5 improves circuit stability. In some embodiments, the fifth resistor R5 can be omitted. The fourth resistor serves to limit current. In some embodiments, the fourth resistor R4 can be omitted.

[0044] To ensure a good linear relationship between the input voltage signal and the output current signal, special attention must be paid to the selection of components. For example, the first resistor R1, the second resistor R2, and the sixth resistor R6 should be low-temperature drift precision resistors or precision potentiometers. Components must be measured before soldering and carefully adjusted. According to the inventor's experiments, the nonlinear distortion of the above voltage-to-current conversion circuit is generally less than 0.03%, and the conversion accuracy meets the requirements. The voltage-to-current converter is equivalent to a constant current source controlled by the input voltage signal, and its output current remains stable regardless of load changes. The voltage-to-current converter is inexpensive, simple in structure, easy to debug, and easy to implement, making it well-suited for complex signal acquisition applications in deep-sea environments.

[0045] Figure 4 This is a circuit diagram of the AC / DC voltage conversion circuit in an embodiment of this disclosure. Combined with... Figure 1 The AC / DC voltage conversion circuit converts the AC power supply voltage provided by the external power supply into a DC power supply voltage before outputting it. This AC / DC voltage conversion circuit can be integrated into the controller or operate independently. The power supply voltage output by the AC / DC voltage conversion circuit powers the controller.

[0046] In some embodiments, an AC / DC voltage conversion circuit is further included to convert the external AC power supply voltage into a DC power supply voltage to power the controller. The AC / DC voltage conversion circuit includes: a second operational amplifier A2, a third operational amplifier A3, an RS flip-flop 1, an NPN type second transistor B2, a seventh resistor R7, a transformer primary N1, a transformer secondary N2, a first diode D1, a second diode D2, an inductor N3, and a capacitor C.

[0047] The non-inverting input of the second operational amplifier A2 receives the reference voltage signal, and its inverting input is connected to the power supply output V. out Its output terminal is connected to the non-inverting input terminal of the third operational amplifier A3;

[0048] The inverting input of the third operational amplifier A3 is connected to the emitter of the second transistor B2, and the output of the third operational amplifier A3 is connected to the R terminal of the RS flip-flop 1.

[0049] The S terminal of RS flip-flop 1 receives the clock signal, and the Q terminal of RS flip-flop 1 is connected to the base of the second transistor B2.

[0050] The seventh resistor R7 is connected between the emitter of the second transistor B2 and the second power supply terminal;

[0051] The primary winding of the transformer, N1, is connected to the power input terminal V. cc Between the collector of the second transistor B2;

[0052] The primary winding N1 and the secondary winding N2 of the transformer are coupled to form a transformer. The secondary winding N2 is connected between the second power supply terminal and the anode of the first diode D1. The anode of the second diode D2 is connected to the second power supply terminal. The cathodes of both the first diode D1 and the second diode D2 are connected to the first terminal of the inductor N3. The second terminal of the inductor N3 is connected to the power output terminal V. out Capacitor C is connected to the power output terminal V. out Between the second power supply terminal and the second power supply terminal.

[0053] This AC / DC voltage converter circuit adds a current feedback control loop inside the ordinary voltage feedback PWM control loop. Therefore, in addition to the functions of a voltage-type PWM controller, it can also detect inductor current, realizing dual-loop control of voltage and current. RS flip-flop 1 serves to eliminate switching bounce. This AC / DC voltage converter circuit has two control closed loops: one feeds the output voltage back to the error amplifier (i.e., the second operational amplifier A2) to generate an error voltage after comparison with the reference voltage; the other compares the voltage generated by the current in the transformer primary across R7 with the error voltage, generates the pulse width of the modulation pulse based on the comparison result, and then passes through an RS flip-flop 1 to eliminate switching bounce, so that the error signal plays an actual control role in the peak inductor current.

[0054] refer to Figure 4 Assuming the input voltage terminal V cc The voltage drops, the rectified DC voltage drops, and the inductor delays the output voltage V. out The voltage drops, and after being delayed by the error amplifier, its output V... ca Rise, output V ca The duty cycle of the voltage signal changes, thus maintaining a constant output voltage. In the current loop, the peak current of inductor N3 also decreases with the input voltage, and the slope of the inductor current, di / dt, decreases, causing the ramp voltage to delay reaching the output terminal V. ca This increases the PWM duty cycle of the output voltage of the second operational amplifier A2, thereby adjusting the output voltage.

[0055] In some other embodiments, the second transistor B2 is an NPN transistor.

[0056] It should be noted that the first diode D1, the second diode D2, the third inductor N3, and the capacitor C constitute an AC-to-DC converter circuit. Other known circuit structures can also be used for the AC-to-DC converter circuit.

[0057] Since changes in input voltage are immediately reflected as changes in inductor current, the output pulse width can be changed in the comparator without going through an error amplifier, resulting in excellent voltage regulation of the system. Due to the fast response and high stability of this AC / DC voltage conversion circuit, the feedback loop has high gain, which does not cause a contradiction between stability and gain, resulting in high accuracy of the output voltage.

[0058] The present disclosure adopts the following technical solution: a robot, including the above-mentioned servo valve control system.

[0059] The various embodiments in this disclosure are described in a progressive manner. The same or similar parts between the various embodiments can be referred to each other. Each embodiment focuses on describing the differences from other embodiments.

[0060] The scope of protection of this disclosure is not limited to the embodiments described above. Obviously, those skilled in the art can make various modifications and variations to this disclosure without departing from its scope and spirit. If such modifications and variations fall within the scope of the claims of this disclosure and their equivalents, then the intent of this disclosure also includes such modifications and variations.

Claims

1. A servo valve control system, characterized in that, include: The system includes a controller and multiple voltage-output digital-to-analog converters (DACs). The chip select signal inputs of the multiple voltage-output DACs are all connected to the same chip select signal output of the controller. The clock signal inputs of the multiple voltage-output DACs are all connected to the same clock signal output of the controller. The serial data inputs and serial data outputs of the controller and the multiple voltage-output DACs are connected in a loop. The controller is configured to sequentially output the digital signals required by the multiple voltage-output DACs through its serial data output. The multiple voltage-output DACs are configured to transmit the received digital signals to their serial data outputs and convert the digital signals received within a set time period into analog voltage signals to drive the corresponding servo valves. The multiple voltage-output DACs are used to connect one-to-one with the servo valves.

2. The system according to claim 1, characterized in that, It also includes a sensor, a voltage-to-current converter, and a current input analog-to-digital converter. The sensor outputs an analog voltage signal at its analog voltage signal output terminal. The voltage-to-current converter converts the analog voltage signal into an analog current signal. The current input analog-to-digital converter is used to convert the analog current signal into a digital signal. The voltage-to-current converter includes: a first resistor, a second resistor, a sixth resistor, a first operational amplifier, and a first transistor. The first resistor is connected in series between the reference voltage terminal and the non-inverting input terminal of the first operational amplifier. The second resistor is connected in series between the analog voltage signal output terminal and the non-inverting input terminal of the first operational amplifier. The output terminal of the first operational amplifier is electrically connected to the base of the first transistor. The two current detection terminals of the current input analog-to-digital converter are connected in series between the first power supply terminal and the collector of the first transistor. The emitter of the first transistor is electrically connected to the inverting input terminal of the first operational amplifier. The sixth resistor is connected between the emitter of the first transistor and the second power supply terminal.

3. The system according to claim 2, characterized in that, The voltage-to-current converter further includes: a third resistor, wherein the two current detection terminals of the current input analog-to-digital converter are connected in series between the first power supply terminal and the collector of the first transistor through the third resistor; and / or, The voltage-to-current converter further includes: a fourth resistor, the first end of which is connected to the output terminal of the first operational amplifier, and the second end of which is connected to the base of the first transistor; and / or, The voltage-to-current converter further includes a fifth resistor, the first end of which is connected to the inverting input of the first operational amplifier, and the second end of which is connected to the emitter of the first transistor.

4. The system according to claim 2, characterized in that, The resistance values ​​of the first resistor and the second resistor are equal.

5. The system according to claim 1, characterized in that, It also includes an AC / DC voltage conversion circuit, which is used to convert the external AC power supply voltage into DC voltage to power the controller. The AC / DC voltage conversion circuit includes: a second operational amplifier, a third operational amplifier, an RS flip-flop, a second transistor, a seventh resistor, a transformer primary, a transformer secondary, and an AC-to-DC conversion circuit. The output terminal of the AC-to-DC conversion circuit serves as the power output terminal. The non-inverting input of the second operational amplifier receives a reference voltage signal, its inverting input is connected to the power supply output, and its output is connected to the non-inverting input of the third operational amplifier. The inverting input terminal of the third operational amplifier is connected to the emitter of the second transistor, and the output terminal of the third operational amplifier is connected to the R terminal of the RS flip-flop. The S terminal of the RS flip-flop receives a clock signal, and the Q terminal of the RS flip-flop is connected to the base of the second transistor. The seventh resistor is connected between the emitter of the second transistor and the second power supply terminal; The primary winding of the transformer is connected between the power input terminal and the collector of the second transistor. The primary and secondary windings of the transformer are coupled to form a transformer, and the secondary winding is connected between the second power supply terminal and the input terminal of the AC-to-DC converter circuit.

6. The system according to claim 5, characterized in that, The AC-to-DC converter circuit includes: a first diode, a second diode, an inductor, and a capacitor; The anode of the first diode serves as the input terminal of the AC-to-DC converter circuit, the anode of the second diode is connected to the second power supply terminal, the anodes of both the first and second diodes are connected to the first terminal of the inductor, the second terminal of the inductor is connected to the power output terminal, and the capacitor is connected between the power output terminal and the second power supply terminal.

7. A robot, characterized in that, include: The servo valve control system according to any one of claims 1 to 6.

Images