Multi-loop air pressure regulating and monitoring system for pneumatic manipulator

Abstract

The invention relates to the field of control systems, in particular to a multi-loop air pressure regulating and monitoring system for a pneumatic manipulator. An upper computer is used for sending a control instruction to a single-chip microcomputer, the single-chip microcomputer sends a processed signal to a photoelectric coupling module, the photoelectric coupling module controls an electromagnetic valve through a 3.3 V-24V signal sent by the single-chip microcomputer, voltage information collected by an air pressure sensor is converted into air pressure information through AD sampling, and the air pressure information is sent to the single-chip microcomputer. The single-chip microcomputer transmits the processed data to an upper computer, so that a user can carry out air pressure regulation and control and air pressure monitoring on the upper computer. The air pump is connected with a power source through a switch to control opening and closing of the air pump, the air pump is connected to the electromagnetic valve through a pressure maintaining valve, connectors of the electromagnetic valve are connected to pneumatic loops of the mechanical arm, and the precision in each pneumatic loop is superior to + / -2kPa.

Description

Technical Field

[0001] The present invention relates to the field of control systems, and more specifically to a multi-circuit air pressure control and monitoring system for a pneumatic manipulator. Background Art

[0002] In recent years, with the rapid development of robotics technology, manipulators are widely used in machinery manufacturing, metallurgy, electronics, light industry, atomic energy and other sectors. Pneumatic manipulators, as one of the main driving methods of manipulators, usually have lower response speed and accuracy than electric manipulators. Therefore, how to improve the control accuracy of pneumatic manipulators to perform fine operations is a key technical challenge facing pneumatic manipulators. Summary of the invention

[0003] The present invention provides a multi-circuit air pressure control and monitoring system for a pneumatic manipulator, the purpose of which is to achieve control of the pressure in each pneumatic path of the manipulator.

[0004] The above purpose is achieved through the following technical solutions:

[0005] A multi-circuit air pressure control and monitoring system for a pneumatic manipulator includes: an upper computer and a lower computer. The lower computer is used to detect the air pressure in each pneumatic circuit of the pneumatic manipulator. The pressure command of the upper computer is sent to the lower computer, and the lower computer realizes the control of the pressure in each pneumatic path.

[0006] It also includes an inflation circuit solenoid valve and an exhaust circuit solenoid valve. The lower computer includes a PCB board, and a single-chip microcomputer, an air pressure sensor, a photoelectric coupling module, a power module and a serial port module connected to the PCB board. The inflation circuit solenoid valve is electrically connected to a photoelectric coupling module, and the exhaust circuit solenoid valve is electrically connected to another photoelectric coupling module. The air pressure sensor, the inflation circuit solenoid valve and the exhaust circuit solenoid valve are respectively connected to three paths in the four-way conversion terminal through a hose. The remaining path of the four-way conversion terminal is used as an output end, and the serial port module is connected to the upper computer.

[0007] The air pressure sensor is connected to the four-way conversion terminal to monitor the air pressure in each pneumatic circuit and feed it back to the microcontroller.

[0008] It also includes an air pump, which is connected to a positive pressure stabilizing valve, and the positive pressure stabilizing valve is connected to an air charging circuit solenoid valve through a hose; a vacuum pump, which is connected to a negative pressure stabilizing valve, and the negative pressure stabilizing valve is connected to an air exhaust circuit solenoid valve through a hose. Multiple groups of positive pressure stabilizing valve-air charging circuit solenoid valves or negative pressure stabilizing valve-air exhaust circuit solenoid valves can be connected in parallel on the air pump or the vacuum pump.

[0009] The gas sensor will monitor the air pressure value in the pneumatic circuit in real time and feed it back to the microcontroller. The microcontroller uses feedback control to make the air pressure value in the air circuit accurate and stable, and transmits the air pressure value monitored by the air pressure sensor to the host computer through the serial port.

[0010] The beneficial effects of the multi-circuit air pressure control and monitoring system for a pneumatic manipulator of the present invention are:

[0011] The host computer sends control instructions to the microcontroller, and the microcontroller sends the processed signal to the photoelectric coupling module. The 3.3V sent by the photoelectric coupling module microcontroller is converted into a 24V signal to control the solenoid valve. The voltage information collected by the air pressure sensor is converted into air pressure information through AD sampling and sent to the microcontroller. The microcontroller then transmits the processed data to the host computer, so that the user can perform air pressure regulation and air pressure monitoring on the host computer. The air pump is connected to the power supply through a switch to control the opening and closing of the air pump. The air pump is connected to the solenoid valve through a pressure regulating valve. The interfaces of the solenoid valve are connected to the pneumatic circuits of the manipulator. The accuracy of each pneumatic circuit is better than ±2kPa. BRIEF DESCRIPTION OF THE DRAWINGS

[0012] Figure 1 It is a schematic diagram of the overall structure of the multi-circuit air pressure control and monitoring system for a pneumatic manipulator of the present invention;

[0013] Figure 2 It is a schematic diagram of a multi-circuit air pressure control and monitoring system for a pneumatic manipulator of the present invention;

[0014] Figure 3 It is a schematic diagram of the control strategy of the multi-loop air pressure regulation and monitoring system for a pneumatic manipulator of the present invention.

[0015] In the figure: power supply 1; switch 2; air pump 3; vacuum pump 4; PCB board 5; single chip microcomputer 501; air pressure sensor 502; photoelectric coupling module 503; power module 504; serial port module 505; positive pressure stabilizing valve 6; negative pressure stabilizing valve 7; air charging circuit solenoid valve 8; air extraction circuit solenoid valve 9; four-way conversion terminal 10; host computer 11. DETAILED DESCRIPTION

[0016] A multi-circuit air pressure control and monitoring system for a pneumatic manipulator, comprising:

[0017] The air pump 3 is connected to the positive pressure stabilizing valve 6 through a hose, and the positive pressure stabilizing valve 6 is connected to the air charging circuit electromagnetic valve 8 through the hose;

[0018] The vacuum pump 4 is connected to the negative pressure stabilizing valve 7 through a hose, and the negative pressure stabilizing valve 7 is connected to the air extraction circuit electromagnetic valve 9 through a hose;

[0019] The lower computer includes a PCB board 5, and a single-chip microcomputer 501, an air pressure sensor 502, a photoelectric coupling module 503, a power module 504 and a serial port module 505 connected to the PCB board 5; the power module 504 is used to supply power to the PCB board 5, the single-chip microcomputer 501, the air pressure sensor 502, the photoelectric coupling module 503 and the serial port module 505;

[0020] Among them, the inflation circuit solenoid valve 8 is electrically connected to the photoelectric coupling module 503 through wires, and the exhaust circuit solenoid valve 9 is electrically connected to the photoelectric coupling module 503 through wires. The photoelectric coupling module 503 can convert the 3.3V signal into a 24V signal to control the solenoid valve, namely the inflation circuit solenoid valve 8 and the exhaust circuit solenoid valve 9. Preferably, the solenoid valve adopts a miniature high-frequency three-way solenoid valve, which can be controlled by a single-chip microcomputer to realize one-way input and three-way output; the air pressure sensor 502, the inflation circuit solenoid valve 8 and the exhaust circuit solenoid valve 9 are respectively connected through hoses The three paths in the four-way conversion terminal 10 are connected, and the remaining path of the four-way conversion terminal 10 is used as an output end; the serial port module 505 is connected to the host computer 11, that is, the communication between the host computer 11 and the slave computer is realized in the connection mode of serial port communication, and the air pressure sensor 502 is an XGZP6847A gas pressure sensor, which is connected to the four-way conversion terminal 10 to monitor the air pressure in each pneumatic circuit and feed it back to the single-chip microcomputer 501. The model of the single-chip microcomputer 501 is preferably stm32F407ZGT6;

[0021] The air pump 3, the vacuum pump 4 and the power module 504 are electrically connected to the power supply 1 through wires, and the power supply 1 is used to supply power to the air pump 3, the vacuum pump 4 and the power module 504. The power supply 1 is provided with a switch 2;

[0022] like Figure 3 As shown, the control strategy adopts pressure closed-loop control. The specific strategy is: the host computer 11 sends the pressure command to the single-chip microcomputer 501, the gas charging circuit solenoid valve 8 and the gas extraction circuit solenoid valve 9 are used as pressure controllers, the single-chip microcomputer 501 converts the pressure command into an air pressure signal and transmits it to the pressure controller, the pressure controller converts the pressure difference into a control command to control the opening and closing time of the solenoid valve, and realizes the control of the pressure in each pneumatic path. At the same time, the air pressure sensor 502 feeds back the pressure signal in the pneumatic path to the single-chip microcomputer 51. Such a closed-loop control strategy can detect and feedback the actual output value in time, and compensate and control the system error, so as to maintain the stability and accuracy of the system.

[0023] When the switch 2 is closed, the power supply 1 supplies power to the power units such as the air pump 3, the vacuum pump 4 and the PCB board 5 in the circuit. The air pump 3 starts to continuously inflate the air path, and the vacuum pump 4 starts to continuously extract air from the air path. The positive pressure and negative pressure values ​​provided by the air pump 3 and the vacuum pump 4 to the air path can be controlled respectively by adjusting the positive pressure regulating valve 6 and the negative pressure regulating valve 7. After the user operates the host computer 11 to send an air pressure control instruction to the PCB board 5 through the serial port, the single-chip microcomputer 501 processes the received instruction into a 3.3V signal and sends it to the photoelectric coupling module 503. The photoelectric coupling module 503 The coupling module 503 converts the 3.3V signal into a 24V signal to control the opening and closing time of the inflation circuit solenoid valve 8 and the exhaust circuit solenoid valve 9 to achieve control of the output pressure; at the same time, the gas sensor 503 will monitor the air pressure value in the pneumatic circuit in real time and feed it back to the single-chip microcomputer 501. The single-chip microcomputer 501 uses feedback control to make the air pressure value in the air circuit accurate and stable, and transmits the air pressure value monitored by the air pressure sensor 502 to the host computer through the serial port. The user can observe the actual air pressure value in each pneumatic path through the air pressure monitoring and quick control interface of the host computer 11.

[0024] Preferably, each pneumatic path is respectively connected to a positive pressure input, a negative pressure input and an air pressure monitoring, and each pneumatic path is independently controlled.

[0025] Since the single-chip microcomputer is easily affected by external interference, and the pneumatic system itself has certain delays and instability, the system control accuracy and stability are usually low. To solve this technical problem, the single-chip microcomputer 51 adopts a digital filtering method to eliminate the influence of possible external interference on the data acquisition process, and adopts a feedforward PID algorithm to ensure the accuracy and stability of the control process.

[0026] There is an exponential relationship of 2 between the positive pressure circuit PWM and the output pressure (P), that is:

[0027] PWM=Ae BP +Ce DP

[0028] Where PWM is the duty cycle, which changes with the pressure P, and A, B, C, and D are constants. When the negative pressure circuit PWM is taken as a certain value, the specific functional relationship between the positive pressure circuit PWM and P can be obtained. In the present invention, this control system is applied to a pneumatic manipulator, preferably a symmetrical six-finger manipulator. When the negative pressure circuit PWM=100, the relationship between the positive pressure circuit PWM and P is:

[0029] PWM = 45.215e 0.0038P +0.025e 0.0371P

[0030] According to this functional relationship, the feedforward PID algorithm is integrated, that is, when the negative pressure circuit PWM is controlled to a certain value, the expected value of the output pressure is given, and the accurate positive pressure circuit PWM can be obtained. The function expression can be expressed as:

[0031] PWM=A×e B×Pe +C×e D×Pe +KP×Bias+KI+Integral_Bias

[0032] The following is a further explanation of the variables in the function expression. Pe is the expected value of the output pressure, Bias is the deviation value, KP is the proportional coefficient, KI is the integral coefficient, Integral_Bias is the cumulative deviation value, KP=Pe / 100, KI=5, Bias=Pe-P, the overall cumulative deviation value Integral_Bias=∑Bias×0.03. This control method can be used to keep the control accuracy of the pneumatic circuit within ±2kPa.

[0033] It is understandable that the pneumatic circuits are more than the three shown in the figure. Within the allowable range of the air pressure of the air pump 3 and the vacuum pump 4, multiple groups of positive pressure stabilizing valves 6-inflation circuit solenoid valves 8 or negative pressure stabilizing valves 7-exhaust circuit solenoid valves 9 can be connected in parallel on the air pump 3 or the vacuum pump 4 to achieve multi-circuit air pressure control with adjustable quantity.

[0034] Preferably, the host computer 11 is designed with QT software, and three interfaces are designed: a serial communication interface, an air pressure monitoring and quick control interface, and a monitoring and fine-tuning interface, which respectively realize the functions of serial communication, air pressure monitoring and control, and manipulator motion trajectory display.

Claims

1. A multi-circuit air pressure control and monitoring system for a pneumatic manipulator, characterized in that: include: The upper computer (11) and the lower computer, the lower computer is used to detect the air pressure in each pneumatic circuit of the pneumatic manipulator, the pressure command of the upper computer (11) is sent to the lower computer, and the lower computer realizes the control of the pressure in each pneumatic path.

2. The multi-circuit air pressure control and monitoring system for a pneumatic manipulator according to claim 1 is characterized in that: The host computer 11 includes a serial communication interface, an air pressure monitoring and quick control interface for realizing air pressure monitoring and control, and a monitoring and fine-tuning interface for displaying and adjusting the motion trajectory of the manipulator.

3. The multi-circuit air pressure control and monitoring system for a pneumatic manipulator according to claim 2 is characterized in that: The invention also comprises an air charging circuit electromagnetic valve (8) and an air extraction circuit electromagnetic valve (9); the lower computer comprises a PCB board (5), and a single chip computer (501), an air pressure sensor (502), a photoelectric coupling module (503), a power module (504) and a serial port module (505) connected to the PCB board (5); the air charging circuit electromagnetic valve (8) is electrically connected to one photoelectric coupling module (503); the air extraction circuit electromagnetic valve (9) is electrically connected to another photoelectric coupling module (503); the air pressure sensor (502), the air charging circuit electromagnetic valve (8) and the air extraction circuit electromagnetic valve (9) are respectively connected to three passages in a four-way conversion terminal (10) through a hose; the remaining passage of the four-way conversion terminal (10) serves as an output end; and the serial port module (505) is connected to the upper computer (11).

4. The multi-circuit air pressure control and monitoring system for a pneumatic manipulator according to claim 3 is characterized in that: The model of the single chip microcomputer (501) is stm32F407ZGT6.

5. The multi-circuit air pressure control and monitoring system for a pneumatic manipulator according to claim 3 is characterized in that the air pressure The sensor (502) is a XGZP6847A gas pressure sensor, which is connected to the four-way conversion terminal (10) to monitor the gas pressure in each pneumatic circuit and feed it back to the single chip computer (501).

6. The multi-circuit air pressure control and monitoring system for a pneumatic manipulator according to claim 3 is characterized in that: The gas charging circuit electromagnetic valve (8) and the gas exhaust circuit electromagnetic valve (9) adopt miniature high-frequency three-way electromagnetic valves.

7. The multi-circuit air pressure control and monitoring system for a pneumatic manipulator according to claim 3 is characterized in that: The invention also comprises an air pump (3), the air pump (3) being connected to a positive pressure stabilizing valve (6), the positive pressure stabilizing valve (6) being connected to an air charging circuit electromagnetic valve (8) via a hose; and a vacuum pump (4), the vacuum pump (4) being connected to a negative pressure stabilizing valve (7), the negative pressure stabilizing valve (7) being connected to an air extraction circuit electromagnetic valve (9) via a hose, and a plurality of groups of positive pressure stabilizing valve (6)-air charging circuit electromagnetic valve (8) or negative pressure stabilizing valve (7)-air extraction circuit electromagnetic valve (9) being connected in parallel on the air pump (3) or the vacuum pump (4).

8. The multi-circuit air pressure control and monitoring system for a pneumatic manipulator according to claim 3 is characterized in that: The photoelectric coupling module (503) converts the 3.3V signal into a 24V signal to control the opening and closing time of the gas charging circuit electromagnetic valve (8) and the gas exhaust circuit electromagnetic valve (9), so as to realize the control of the output pressure.

9. The multi-circuit air pressure control and monitoring system for a pneumatic manipulator according to claim 3 is characterized in that: The gas sensor (502) monitors the air pressure value in the pneumatic circuit in real time and feeds back to the single chip microcomputer (501). The single chip microcomputer (501) makes the air pressure value in the air circuit accurate and stable through feedback control, and transmits the air pressure value monitored by the air pressure sensor (502) to the host computer through the serial port.

10. The multi-circuit air pressure control and monitoring system for a pneumatic manipulator according to claim 3, characterized in that: Each pneumatic path is respectively connected to a positive pressure input, a negative pressure input and an air pressure monitoring, and each pneumatic path is independently controlled.

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