Hydraulic swing joint testing system and motion control method thereof

Abstract

The invention relates to a hydraulic swing joint testing system and a motion control method thereof. The system is composed of a hydraulic driving device, a loading device, a measuring device and a control processing device. Firstly, the hydraulic driving device controls the hydraulic swing joint and provides power for the hydraulic swing joint, then rotation of the hydraulic swing joint is converted into linear motion through a sliding block and a connecting rod structure in the loading device, and data are collected through the measuring device. The control processing device processes the data to adjust the motion states of the hydraulic swing joint and the double-acting piston cylinder, the dynamic response and dynamic characteristics of the hydraulic swing joint are recorded in real time, test results are obtained, and the test results comprise the positioning precision, the load capacity and the dynamic response capacity of the hydraulic swing joint. Compared with the prior art, the method has the advantages of low measurement cost, high measurement precision, wide application and the like.

Description

Technical Field

[0001] The present invention relates to the technical field of measurement and control, and in particular, to a hydraulic swing joint test system and a motion control method thereof. Background Art

[0002] The hydraulic swing joint is suitable for the joints of robotic arms or legged robots that pursue load capacity. It is an electro-mechanical-hydraulic integrated component with a hydraulic swing cylinder as the driving element, integrated with an encoder, a pressure sensor, a controller, and a hydraulic drive circuit. It uses hydraulic power to generate swing and output torque, and has the advantages of large output torque, high power ratio, long service life, and self-overload protection compared with electric joints.

[0003] The core component of the hydraulic swing joint is the hydraulic swing cylinder. Existing swing cylinders include vane type, rack type, etc. Among them, the double helix swing cylinder is a new type of hydraulic drive component that uses two-stage helical pairs to convert the linear motion of the piston into the rotation of the output shaft. It has the advantages of high positioning accuracy, large output torque, compact structure, and smooth motion. However, compared with foreign countries, the positioning accuracy and load capacity of domestic double helix swing cylinders need to be further improved, which requires accurate measurement of their relevant performance parameters to analyze the influencing factors. In addition, to achieve the automatic control of robot joints, it is necessary to measure the output torque in real time. However, due to the large output torque of hydraulic joints, it is not feasible to integrate a torque sensor inside the joint, and indirect measurement can only be carried out through the input fluid pressure.

[0004] Most of the existing comprehensive test platforms for robot joints are aimed at electric joints with RV (Rotary Vector) reducers as the core, and are not suitable for the test of hydraulic swing joints. For example, an industrial robot joint reducer comprehensive test platform disclosed in CN105181329B, the axes of the tested joint, sensor, and load are all connected in series, with high requirements for the coaxiality of installation and great influence on the measurement accuracy. Summary of the Invention

[0005] The purpose of the present invention is to overcome the above-mentioned defects existing in the prior art and provide a hydraulic swing joint test system and a motion control method thereof.

[0006] The purpose of the present invention can be achieved by the following technical solutions:

[0007] According to one aspect of the present invention, a hydraulic swing joint test system is provided. The system consists of a hydraulic drive device, a loading device, a measuring device, and a control and processing device. The loading device includes a double-acting piston cylinder 2, a slider 5, a hydrostatic guide 3, a bearing block 10, a first connecting rod 6, and a second connecting rod 8. The hydraulic swing joint 7 to be tested is fixed between the first connecting rod 6 and the second connecting rod 8 via a flange. The other end of the first connecting rod 6 is connected to the slider 5, which is placed on the hydrostatic guide 3 and connected to the piston rod of the double-acting piston cylinder 2. The other end of the second connecting rod 8 is connected to the bearing block 10.

[0008] As a preferred technical solution, the hydraulic drive device includes a motor, a fixed-displacement hydraulic pump 13, an electro-hydraulic servo valve 15, an oil tank 11, a filter 12, a check valve 14, and a relief valve 18.

[0009] As a preferred technical solution, the measuring device includes an incremental photoelectric encoder 9, a tension and compression sensor 4, and a liquid pressure sensor.

[0010] As a preferred technical solution, the incremental photoelectric encoder 9 is arranged between the second connecting rod 8 and the bearing block 10. The tension and compression sensor 4 is arranged between the slider 5 and the piston rod of the double-acting piston cylinder 2. The liquid pressure sensor is arranged at the oil inlet and outlet of the hydraulic swing joint 7.

[0011] As a preferred technical solution, the control and processing device includes a photoelectric encoder counting card, a liquid pressure sensor A / D acquisition card, a tension and compression sensor 4 A / D acquisition card, a computer, and a servo amplifier. Among them, the computer is electrically connected to the other four parts via a CAN bus.

[0012] As a preferred technical solution, a test bench is provided in the test system. The double-acting piston cylinder 2, the hydrostatic guide 3, and the bearing block 10 are all fixed to the test bench by threads.

[0013] According to another aspect of the present invention, a hydraulic swing joint test method is provided. This method is applied to a hydraulic swing joint test system as described above. First, the hydraulic drive device provides power for the hydraulic swing joint 7 to control the steering and output torque of the hydraulic swing joint 7. Then, the slider 5 and the connecting rod structure in the loading device convert the rotation of the hydraulic swing joint 7 into linear motion. The measuring device collects data and transmits the data to the control and processing device. The control and processing device processes the data to adjust the motion states of the hydraulic swing joint 7 and the double-acting piston cylinder 2. The control and processing device records the dynamic response and dynamic characteristics of the hydraulic swing joint 7 in real time to obtain the test results. The test results include the positioning accuracy, load capacity, and dynamic response ability of the hydraulic swing joint 7.

[0014] As a preferred technical solution, a hydraulic drive device provides power for the hydraulic swing joint 7. The process of controlling the steering and output torque of the hydraulic swing joint 7 is as follows: First, the fixed-displacement hydraulic pump 13 in the hydraulic drive device sucks the oil filtered by the filter 12 from the oil tank 11 under the drive of the motor and pressurizes it. Then, the check valve 14 prevents the oil from flowing back when the fixed-displacement hydraulic pump 13 stops working, and the relief valve 18 ensures that the outlet pressure of the fixed-displacement hydraulic pump 13 is always constant. At this time, the hydraulic joint electro-hydraulic servo valve 15 controls the flow direction and pressure of the liquid flowing into the hydraulic swing joint 7 according to the electrical signal provided by the corresponding servo amplifier, thereby controlling the steering and output torque of the hydraulic swing joint 7.

[0015] As a preferred technical solution, the control processing device processes the data to adjust the motion states of the hydraulic swing joint 7 and the double-acting piston cylinder 2. The specific process is as follows: First, the photoelectric encoder counter card, the liquid pressure sensor A / D (analog / digital) acquisition card, and the tension and compression sensor 4 A / D acquisition card respectively collect the output data of the incremental photoelectric encoder 9, the liquid pressure sensor, and the tension and compression sensor 4, and transmit the combined data to the computer through the Controller Area Network (CAN) bus. The computer obtains the target signal, and this target signal is transmitted to the servo amplifier through the CAN bus. Then, the servo amplifier generates electrical signals corresponding to the target signal respectively, and then transmits the electrical signals to the hydraulic joint electro-hydraulic servo valve 15 and the piston cylinder electro-hydraulic servo valve 15 to control the output torque of the hydraulic swing joint 7, the angular displacement of the hydraulic swing joint 7, or the output force of the double-acting piston cylinder 2.

[0016] As a preferred technical solution, the dynamic response includes torque, angular displacement, and angular velocity, and the dynamic characteristics include response speed and stability.

[0017] Compared with the prior art, the present invention has the following beneficial effects:

[0018] 1. The system in the present invention is composed of a hydraulic drive device, a loading device, a measuring device, and a control processing device. Among them, the loading device includes a double-acting piston cylinder, a slider, a hydrostatic guide rail, a bearing block, a first connecting rod, and a second connecting rod. The hydraulic swing joint to be measured is fixed between the first connecting rod and the second connecting rod via a flange. The other end of the first connecting rod is connected to the slider, which is placed on the hydrostatic guide rail and connected to the piston rod of the double-acting piston cylinder. The other end of the second connecting rod is connected to the bearing block. The slider and connecting rod structure is used in this system to convert rotation into linear motion, and then a pressure sensor is used for measurement, which makes the measurement cost of this system low and the measurement accuracy high.

[0019] 2. In the present invention, the incremental photoelectric encoder is arranged between the second connecting rod and the bearing block, the tensile and compressive force sensor is arranged between the slider and the piston rod of the double-acting piston cylinder, and the liquid pressure sensor is arranged in the hydraulic driving device. When testing this system, there is no need to reinstall the encoder, and there is no requirement for coaxiality between components. This enables the present invention to be widely applied to the measurement of hydraulic swing joints in multiple scenarios, making the present invention have wide applicability.

[0020] 3. In the control processing device of the present invention, first, the output data of the incremental photoelectric encoder, the liquid pressure sensor, and the tensile and compressive force sensor are respectively collected, and the combined data is transmitted to the computer through the CAN bus; the target signal is obtained by the computer, and this target signal is transmitted to the servo amplifier through the CAN bus; then the servo amplifier generates electrical signals corresponding to the target signal respectively, and then transmits the electrical signals to the electro-hydraulic servo valve of the hydraulic joint and the electro-hydraulic servo valve of the piston cylinder to control the output torque of the hydraulic swing joint, the angular displacement of the hydraulic swing joint, or the output force of the double-acting piston cylinder, so that this method can be used to calibrate the relationship between the actual output torque of the hydraulic swing joint and the input oil pressure. Description of the Drawings

[0021] Figure 1 It is a schematic structural diagram of the hydraulic swing joint test system in the present invention;

[0022] Figure 2 It is a schematic flow diagram of the control processing device in the present invention;

[0023] Figure 3 It is a schematic structural diagram of the hydraulic driving device in the present invention;

[0024] In the figure, 1 is the loading platform, 2 is the double-acting piston cylinder, 3 is the hydrostatic guide rail, 4 is the tensile and compressive force sensor, 5 is the slider, 6 is the first connecting rod, 7 is the hydraulic swing joint, 8 is the second connecting rod, 9 is the incremental photoelectric encoder, 10 is the bearing block, 11 is the fuel tank, 12 is the filter, 13 is the quantitative hydraulic pump, 14 is the one-way valve, 15 is the electro-hydraulic servo valve, 16, 17, 19, and 20 are the liquid pressure sensors, and 18 is the overflow valve. Detailed Embodiments

[0025] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, rather than all the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention.

[0026] The hydraulic swing joint is an electro-mechanical-hydraulic integrated component that uses a hydraulic swing cylinder as the driving element and integrates an encoder, a pressure sensor, a controller, and a hydraulic drive circuit. It uses hydraulic pressure as the power to generate swing and output torque, and has the advantages of large output torque, high power ratio, long service life, and built-in overload protection compared with electric joints. It is suitable for the joints of robotic arms or legged robots that pursue load capacity.

[0027] The core component of the hydraulic swing joint is the hydraulic swing cylinder. Existing swing cylinders include vane type, rack type, etc. Among them, the double helix swing cylinder is a new type of hydraulic drive component that uses two-stage screw pairs to convert the linear motion of the piston into the rotation of the output shaft. It has the advantages of high positioning accuracy, large output torque, compact structure, and smooth movement. However, compared with foreign countries, the positioning accuracy and load capacity of domestic double helix swing cylinders need to be further improved, which requires accurate measurement of their relevant performance parameters to analyze the influencing factors. In addition, to achieve the automatic control of robotic joints, it is necessary to measure their output torque in real time. However, due to the large output torque of hydraulic joints, it is not feasible to integrate a torque sensor inside the joint, and indirect measurement can only be carried out through the input fluid pressure. To ensure the accuracy and reliability of indirect measurement, it is obviously very necessary to calibrate the relationship between the actual output torque of the joint and the input pressure. Most of the existing comprehensive test platforms for robotic joints are aimed at electric joints with RV reducers as the core and are not suitable for the testing of hydraulic swing joints. Moreover, the axes of the tested joints, sensors, and loads are connected in series, which requires high coaxiality for installation and has a great impact on the measurement accuracy. Therefore, it is very necessary to invent a comprehensive test device suitable for the performance testing of hydraulic swing joints.

[0028] Embodiment 1

[0029] In this embodiment, a hydraulic swing joint test system is applied. As shown in Figure 1 , it is composed of a hydraulic drive device, a loading device, a measuring device, and a control and processing device;

[0030] The loading device includes a double-acting piston cylinder 2, a slider 5, a hydrostatic guide 3, a bearing block 10, a first connecting rod 6 and a second connecting rod 8. The hydraulic swing joint 7 to be measured is fixed between the first connecting rod 6 and the second connecting rod 8 via a flange. The other end of the first connecting rod 6 is connected to the slider 5, which is placed on the hydrostatic guide 3 and connected to the piston rod of the double-acting piston cylinder 2. The other end of the second connecting rod 8 is connected to the bearing block 10. The hydraulic drive device includes a motor, a fixed-displacement hydraulic pump 13, an electro-hydraulic servo valve 15, an oil tank 11, a filter 12, a check valve 14 and a relief valve 18. The measuring device includes an incremental photoelectric encoder 9, a tensile and compressive force sensor 4 and a liquid pressure sensor. The incremental photoelectric encoder 9 is arranged between the second connecting rod 8 and the bearing block 10. The tensile and compressive force sensor 4 is arranged between the slider 5 and the piston rod of the double-acting piston cylinder 2. The liquid pressure sensor is arranged at the oil inlet and outlet of the hydraulic swing joint 7. The control and processing device includes a photoelectric encoder counting card, a liquid pressure sensor A / D acquisition card, a tensile and compressive force sensor 4 A / D acquisition card, a computer and a servo amplifier. Among them, the computer is electrically connected to the other four parts via a CAN bus.

[0031] In this embodiment, the swing of the hydraulic swing joint 7 is converted into the linear motion of the slider 5 and the swing of the connecting rod through the slider 5 connecting rod mechanism. The incremental photoelectric encoder 9 installed between the second connecting rod 8 and the bearing block 10 can measure the angular displacement and angular velocity of the connecting rod. If the lengths of the first connecting rod 6 and the second connecting rod 8 are equal, then the angular displacement and angular velocity of the second connecting rod 8 are half of the angular displacement and angular velocity of the hydraulic swing joint 7. Thus, the motion parameters of the hydraulic swing joint 7 can be indirectly measured.

[0032] In this embodiment, a tensile and compressive force sensor 4 is installed between the slider 5 and the piston rod of the double-acting piston cylinder 2, and the tensile and compressive forces between the two can be measured. During the test, the slider 5 connecting rod mechanism is in force balance and moves at a constant speed. The relationship between the tensile or compressive force received by the slider 5 and the output torque of the hydraulic swing joint 7 can be obtained by the virtual displacement principle. Thus, the output torque of the hydraulic swing joint 7 can be indirectly measured. By controlling the output force of the double-acting piston cylinder 2 to change according to a certain law, the output torque of the hydraulic swing joint 7 can also be made to change according to a certain law, so as to analyze its dynamic characteristics.

[0033] In this embodiment, the measurement results of the incremental photoelectric encoder 9, the liquid pressure sensor and the tensile and compressive force sensor 4 are converted into digital signals by their respective corresponding acquisition cards and transmitted to the computer via the CAN bus. After being processed by the computer program, the angular displacement and angular velocity of the hydraulic swing joint 7, the ideal output torque of the hydraulic swing joint 7, the output force of the double-acting piston cylinder 2, and the actual output torque of the hydraulic swing joint 7 are obtained.

[0034] The computer generates a target signal based on the output torque of the hydraulic swing joint 7 and the load force of the double-acting piston cylinder 2 required by the test, in combination with the feedback signals from each sensor. The target signal is transmitted to the corresponding servo amplifier via the CAN bus. The servo amplifiers respectively generate sufficiently large electrical signals according to their respective target signals to control the movement of the spools of the electro-hydraulic servo valve 15 of the hydraulic joint and the electro-hydraulic servo valve 15 of the piston cylinder, so as to control the flow direction and pressure of the hydraulic fluid input to the hydraulic swing joint 7 and the double-acting piston cylinder 2, thereby controlling the output torque of the hydraulic swing joint 7 and the output force of the double-acting piston cylinder 2. Or control the flow rate of the hydraulic fluid input to the hydraulic swing joint 7, thereby controlling its angular displacement.

[0035] In summary, in this system, the slider 5 and the connecting rod structure are used to convert rotational motion into linear motion, and then a pressure sensor is used for measurement, making the measurement cost low and the measurement accuracy high. And it can be widely applied to the measurement of hydraulic swing joints in multiple scenarios, with wide applicability.

[0036] Embodiment 2

[0037] In this embodiment, a test method for a hydraulic swing joint is applied. In this method, first, a hydraulic drive device provides power for the hydraulic swing joint 7 to control the steering and output torque of the hydraulic swing joint 7; then, the slider 5 and the connecting rod structure in the loading device convert the rotational motion of the hydraulic swing joint 7 into linear motion, and a measuring device is used to collect data and transmit the data to a control and processing device. The control and processing device processes the data to adjust the motion states of the hydraulic swing joint 7 and the double-acting piston cylinder 2, and the control and processing device records the dynamic response and dynamic characteristics of the hydraulic swing joint 7 in real time to obtain the test results; the test results include the positioning accuracy, load capacity, and dynamic response ability of the hydraulic swing joint 7.

[0038] In this embodiment, the dynamic response includes torque, angular displacement, and angular velocity, and the dynamic characteristics include response speed and stability.

[0039] In this embodiment, a hydraulic drive device provides power for the hydraulic swing joint 7. The schematic structural diagram of the hydraulic drive device is as Figure 3 shown. The process of controlling the steering and output torque of the hydraulic swing joint 7 is as follows: First, the fixed-displacement hydraulic pump 13 in the hydraulic drive device sucks the oil fluid filtered by the filter 12 from the oil tank 11 under the drive of the motor and pressurizes it; then, the check valve 14 prevents the oil fluid from flowing back when the fixed-displacement hydraulic pump 13 stops working, and the relief valve 18 ensures that the outlet pressure of the fixed-displacement hydraulic pump 13 is always constant. At this time, the electro-hydraulic servo valve 15 of the hydraulic joint controls the flow direction and pressure of the hydraulic fluid flowing into the hydraulic swing joint 7 under the drive of the electrical signal provided by the corresponding servo amplifier, thereby controlling the steering and output torque of the hydraulic swing joint 7.

[0040] In this embodiment, the control processing device processes the data to adjust the motion states of the hydraulic swing joint 7 and the double-acting piston cylinder 2 as follows: Figure 2 As shown in the figure, the specific process is as follows: First, the photoelectric encoder counting card, the liquid pressure sensor A / D acquisition card, and the tension-compression direction sensor 4 A / D acquisition card respectively collect the output data of the incremental photoelectric encoder 9, the liquid pressure sensor, and the tension-compression direction sensor 4, and transmit the combined data to the computer through the CAN bus; the computer obtains the target signal, and this target signal is transmitted to the servo amplifier through the CAN bus; then the servo amplifier generates the corresponding electrical signals respectively, and then transmits the electrical signals to the electro-hydraulic servo valve 15 of the hydraulic joint and the electro-hydraulic servo valve 15 of the piston cylinder to control the output torque of the hydraulic swing joint 7, the angular displacement of the hydraulic swing joint 7, or the output force of the double-acting piston cylinder 2.

[0041] In this embodiment, its mechanical structure includes a loading table 1, a double-acting piston cylinder 2, a hydrostatic guide rail 3, a tension-compression direction sensor 4, a slider 5, a connecting rod, a hydraulic swing joint 7, an incremental photoelectric encoder 9, and a bearing block 10. Its test parameters include positioning accuracy, load capacity, and dynamic response ability, and its components include a loading device, a measuring device, a hydraulic drive circuit, and a control processing device.

[0042] In this embodiment, the working principle of the loading device is that the slider 5 connecting rod mechanism is used to convert the rotation of the joint into the linear motion of the slider 5, and a linear piston cylinder is used for loading, and the output load size is adjusted by the corresponding controller. The measuring device includes an incremental encoder connected to the hinge support shaft for measuring angular displacement and angular velocity; a piezoelectric sensor installed at the output end of the piston cylinder for measuring tensile and compressive forces. The hydraulic drive circuit includes the oil supply circuit of the hydraulic joint and the oil supply circuit of the linear piston cylinder, which are specifically composed of a fixed-displacement hydraulic pump 13, an electro-hydraulic servo valve 15, and other oil circuit auxiliary devices. The control processing device includes the sensor of the test bench, the data acquisition and transmission module of the internal sensor of the hydraulic joint, and the controller of the electro-hydraulic servo valve 15.

[0043] In this embodiment, both ends of the hydraulic swing joint 7 are connected to the large end of the connecting rod through flanges and are also connected to the large end of the connecting rod through the housing base. The small end of the connecting rod is installed on the bearing block 10 and can swing within a certain range. The incremental photoelectric encoder 9 is fixed on the bearing block 10, and the input shaft is connected to the shaft of the small end of the connecting rod. The bearing block 10 is fixed to the loading table 1 by threaded connection. The small end of the connecting rod is hinged to the slider 5, and the two can rotate relative to each other. The slider 5 moves linearly on the hydrostatic guide rail 3, and the hydrostatic support between the two results in very little friction. The hydrostatic guide rail 3 is fixed to the loading table 1 by threaded connection. The tension-compression direction sensor 4 is connected to the slider 5 and the piston rod of the double-acting piston cylinder 2 by threads to measure the tensile or compressive force between the two. The double-acting piston cylinder 2 is fixed to the loading table 1 by threaded connection.

[0044] In this embodiment, the quantitative hydraulic pump 13 sucks the oil filtered by the filter 12 from the oil tank 11 under the drive of the motor and pressurizes it. The check valve 14 prevents the oil from flowing back when the quantitative hydraulic pump 13 stops working. The relief valve 18 ensures that the outlet pressure of the quantitative hydraulic pump 13 is always constant. The hydraulic joint electro-hydraulic servo valve 15 controls the flow direction and pressure of the liquid flowing into the hydraulic swing joint 7 under the drive of the electrical signal provided by the corresponding servo amplifier, so as to control the steering and output torque of the hydraulic swing joint 7. The liquid pressure sensor measures the pressures at the inlet and outlet ports of the hydraulic swing joint 7, and thus calculates its output torque. The piston cylinder electro-hydraulic servo valve 15 controls the flow direction and pressure of the liquid flowing into the double-acting piston cylinder 2 under the drive of the electrical signal provided by the corresponding servo amplifier, so as to control the movement direction and output force of the double-acting piston cylinder 2. The liquid pressure sensor measures the pressures at the inlet and outlet ports of the double-acting piston cylinder 2, and thus calculates its output force.

[0045] In this embodiment, as Figure 2 shown, the photoelectric encoder counting card, the liquid pressure sensor A / D acquisition card, and the tension and compression direction sensor 4 A / D acquisition card respectively collect the output data of the incremental photoelectric encoder 9, the liquid pressure sensor, and the tension and compression direction sensor 4, and transmit them to the computer through the CAN bus. The computer generates a target signal and transmits it to the servo amplifier through the CAN bus. The servo amplifier generates corresponding electrical signals respectively and transmits them to the hydraulic joint electro-hydraulic servo valve 15 and the piston cylinder electro-hydraulic servo valve 15 to control the output torque of the hydraulic swing joint 7 and the output force of the double-acting piston cylinder 2, or the angular displacement of the hydraulic swing joint 7.

[0046] In summary, this method uses a slider and connecting rod structure to convert rotation into linear motion, and then uses sensors for measurement. Its measurement cost is low and the measurement accuracy is high. Moreover, this method can also be used to calibrate the relationship between the actual output torque of the hydraulic swing joint and the input oil pressure.

[0047] The above is only the specific implementation manner of the present invention, but the protection scope of the present invention is not limited thereto. Any person skilled in the art within the technical scope disclosed by the present invention can easily think of various equivalent modifications or substitutions, and these modifications or substitutions should all be covered within the protection scope of the present invention. Therefore, the protection scope of the present invention shall be subject to the protection scope of the claims.

Claims

1. A hydraulic swing joint testing system, characterized in that: The system consists of a hydraulic drive device, a loading device, a measuring device and a control processing device; wherein the control processing device is connected to the hydraulic drive device and is used to process data to generate a control signal and input the control signal to the hydraulic drive device; the hydraulic drive device is connected to the loading device and is used to control a double-acting piston cylinder (2) and a hydraulic swing joint (7) in the loading device and provide power therefor; a slider (5) and a connecting rod in the loading device convert the rotation of the hydraulic swing joint into a linear motion of the slider; the measuring device is distributed in the loading device and is used to measure the state data of the hydraulic swing joint (7); it is connected to the control processing device and inputs the measured state data into the control processing device.

2. A hydraulic swing joint testing system according to claim 1, characterized in that: The loading device comprises a double-acting piston cylinder (2), a slider (5), a hydrostatic guide rail (3), a bearing seat (10), a first connecting rod (6) and a second connecting rod (8); the hydraulic swing joint (7) to be tested is fixed between the first connecting rod (6) and the second connecting rod (8) via a flange; the other end of the first connecting rod (6) is connected to the slider (5), the slider (5) is placed on the hydrostatic guide rail (3) and is connected to the piston rod of the double-acting piston cylinder (2); the other end of the second connecting rod (8) is connected to the bearing seat (10).

3. A hydraulic swing joint testing system according to claim 1, characterized in that: The hydraulic drive device comprises an electric motor, a quantitative hydraulic pump (13), an electro-hydraulic servo valve (15), an oil tank (11), a filter (12), a one-way valve (14) and a relief valve (18).

4. A hydraulic swing joint testing system according to claim 1, characterized in that: The measuring device comprises an incremental photoelectric encoder (9), a tension and compression sensor (4) and a liquid pressure sensor; wherein the incremental photoelectric encoder (9) is arranged between the second connecting rod (8) and the bearing seat (10), the tension and compression sensor 4 is arranged between the slider (5) and the piston rod of the double-acting piston cylinder (2), and the liquid pressure sensor is arranged at the oil inlet and the oil outlet of the hydraulic swing joint (7).

5. A hydraulic swing joint testing system according to claim 1, characterized in that: The control processing device comprises a photoelectric encoder counting card, a liquid pressure sensor A / D acquisition card, a tension and compression sensor A / D acquisition card, a computer and a servo amplifier, wherein the computer is electrically connected to the other four parts via a CAN bus.

6. A hydraulic swing joint testing system according to claim 1, characterized in that: The test system is provided with a test bench, and the double-acting piston cylinder (2), the static pressure guide rail (3) and the bearing seat (10) are all fixed on the test bench by means of threads.

7. A motion control method for a hydraulic swing joint test system, characterized in that: The method is applied to a hydraulic swing joint testing system as described in any one of claims 1 to 6, S1, firstly, the control processing device inputs an initial control signal into the hydraulic driving device, and the hydraulic driving device provides power to the hydraulic swing joint (7) to control the steering direction and output torque of the hydraulic swing joint (7); S2, the slider (5) and the connecting rod structure in the loading device convert the rotation of the hydraulic swing joint (7) into linear motion; S3, using a measuring device to measure state data of the hydraulic swing joint (7), and transmitting the state data to a control processing device; S4. Process the state data using the control processing device and output a control signal to the hydraulic drive device, which adjusts the motion state of the hydraulic swing joint (7) and the double-acting piston cylinder (2).

8. A method for testing a hydraulic swing joint according to claim 7, characterized in that: The hydraulic drive device comprises an electric motor, a quantitative hydraulic pump (13), an electro-hydraulic servo valve (15), an oil tank (11), a filter (12), a one-way valve (14) and a relief valve (18), and provides power to the hydraulic swing joint (7). The process of controlling the steering direction and output torque of the hydraulic swing joint (7) is as follows: first, the quantitative hydraulic pump (13) in the hydraulic drive device, driven by the electric motor, draws oil filtered by the filter (12) from the oil tank (11) and pressurizes the oil; The one-way valve (14) prevents the oil from flowing back when the quantitative hydraulic pump (13) stops working, and the overflow valve (18) ensures that the outlet pressure of the quantitative hydraulic pump (13) is always constant. At this time, the hydraulic joint electro-hydraulic servo valve (15) is driven by the electrical signal provided by the corresponding servo amplifier to control the flow direction and pressure of the liquid flowing into the hydraulic swing joint (7), thereby controlling the steering direction and output torque of the hydraulic swing joint (7).

9. A method for testing a hydraulic swing joint according to claim 7, characterized in that: The measuring device comprises an incremental photoelectric encoder (9), a tension and compression sensor (4) and a liquid pressure sensor. The process of measuring the state data of the hydraulic swing joint (7) by the measuring device comprises: using the incremental photoelectric encoder (9) to measure the angular displacement and angular velocity of the hydraulic swing joint (7), using the tension and compression sensor (4) to measure the output force of the double-acting piston cylinder (2), and using the liquid pressure sensor to measure the pressure of the oil inlet and outlet of the hydraulic swing joint (7), thereby calculating its output torque.

10. A method for testing a hydraulic swing joint according to claim 7, characterized in that: The specific process of processing the data by the control processing device to adjust the motion state of the hydraulic swing joint (7) and the double-acting piston cylinder (2) is as follows: first, the output data of the measuring device, i.e., the state data of the hydraulic swing joint (7), is collected by the photoelectric encoder counting card, the liquid pressure sensor A / D acquisition card and the tension and compression direction sensor 4 A / D acquisition card, and then the state data is transmitted to the computer through the CAN bus; the target signal is obtained by the computer, and the target signal is transmitted to the servo amplifier through the CAN bus; Then the servo amplifier generates electrical signals corresponding to the target signals respectively, and transmits the electrical signals to the hydraulic joint electro-hydraulic servo valve (15) and the piston cylinder electro-hydraulic servo valve (15) to control the output torque of the hydraulic swing joint (7), the angular displacement of the hydraulic swing joint (7) or the output force of the double-acting piston cylinder (2).

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