Industrial mechanical arm rigidity measuring system and method

Abstract

The invention discloses an industrial mechanical arm rigidity measuring system and method, relates to the technical field of industrial mechanical arms, and aims at providing the industrial mechanical arm rigidity measuring system and method which can measure the rigidity of the whole joint and a connecting rod of an industrial robot and provide data support for a vibration suppression algorithm of the industrial robot. The industrial mechanical arm rigidity measuring system comprises a force application assembly, a to-be-measured body, a measuring assembly and a driving and collecting assembly, the driving and collecting assembly is connected with the force application assembly, the to-be-measured body and the measuring assembly, the force application assembly comprises a plurality of linear modules, and the linear modules drive a force application seat to apply force to the to-be-measured body. Pressure sensors are arranged around the force application seat, the measuring assembly comprises a laser displacement sensor, the laser displacement sensor is used for collecting the displacement amount of a measured point of the to-be-measured body, and data of the applied force and the displacement amount can be transmitted to the driving and collecting assembly.

Description

Technical Field

[0001] The present invention relates to the technical field of industrial robotic arms, and in particular, to a system and method for measuring the stiffness of an industrial robotic arm. Background Art

[0002] Industrial robots have become extremely important and indispensable equipment in today's modern manufacturing industry. Their performance directly affects production efficiency and product quality. With the continuous progress of industrial robot technology and the continuous expansion of application fields, customers' requirements for the performance of industrial robots are gradually increasing, which prompts industrial robots to have high precision, fast dynamic response speed, and good stability.

[0003] For traditional six-axis industrial robots, due to the particularity of their structures, their overall stiffness and natural frequency are relatively low. During the rapid operation of the robotic arm, process jitter or residual jitter is likely to occur, which greatly limits the application fields of industrial robots.

[0004] With the continuous iteration and update of technology, it has been found in engineering practice that the jitter of the robotic arm can be effectively suppressed by the vibration suppression algorithms of the upper computer or servo. However, the vibration suppression algorithms have a high dependence on the actual stiffness and natural frequency of the robotic arm. Traditionally, the stiffness of the robotic arm link is obtained through modeling, but there is usually a large error between the stiffness obtained by this method and the actual stiffness of the robotic arm. When the modeled stiffness data is imported into the vibration suppression algorithm, it often causes the failure of the vibration suppression algorithm and even has the opposite effect. In the engineering field, there is an urgent need for a system and method that can measure the actual stiffness of the joints and links of industrial robots. Summary of the Invention

[0005] The technical problem to be solved by the present invention is to provide a system and method for measuring the stiffness of an industrial robotic arm, which can measure the stiffness of the entire joints and links of an industrial robot and provide data support for the vibration suppression algorithm of the industrial robot.

[0006] One of the technical solutions provided by the present invention is an industrial robotic arm stiffness measurement system, including a force application component, a to-be-measured body, a measurement component, and a driving and acquisition component. The driving and acquisition component is respectively connected to the force application component, the to-be-measured body, and the measurement component. The force application component includes a plurality of linear modules, and the linear modules drive a force application seat to apply a force to the to-be-measured body. A pressure sensor is arranged around the force application seat. The measurement component includes a laser displacement sensor, and the laser displacement sensor is used to collect the displacement amount at the measured point of the to-be-measured body. The data of the applied force and the displacement amount can be transmitted to the driving and acquisition component.

[0007] An industrial robotic arm stiffness measurement system of the present invention, wherein the force application component includes a base, and a plurality of counterweight blocks are arranged on the base.

[0008] An industrial robotic arm stiffness measurement system of the present invention, wherein the linear module includes a cross-shaped linear module and a vertical linear module. The cross-shaped linear module is arranged on the base of the force application component. A support seat is arranged on the slider of the cross-shaped linear module. The vertical linear module is arranged on the support seat, and a force application seat is arranged on the slider of the vertical linear module.

[0009] An industrial robotic arm stiffness measurement system of the present invention, wherein pressure sensors are arranged at the upper and lower parts and on both side plates of the force application seat.

[0010] An industrial robotic arm stiffness measurement system of the present invention, wherein the measurement component includes a vertical support column. A horizontal support column is installed on the vertical support column through a pillar fixing clamp, and a laser displacement sensor is arranged on the horizontal support column.

[0011] An industrial robotic arm stiffness measurement system of the present invention, wherein the driving and acquisition component includes a control cabinet, a driver, and a data acquisition card.

[0012] An industrial robotic arm stiffness measurement system of the present invention, wherein the control cabinet is connected to the object to be measured and is used to control the posture of the object to be measured. The driver can communicate with the linear module in the force application component.

[0013] An industrial robotic arm stiffness measurement system of the present invention, which further includes a host computer, and the host computer can communicate with the control cabinet and the driver respectively.

[0014] An industrial robotic arm stiffness measurement system of the present invention, wherein the data acquisition card can collect the data of the pressure sensor and the laser displacement sensor respectively.

[0015] Another technical solution provided by the present invention is an industrial robotic arm stiffness measurement method, which includes the following steps:

[0016] S10, System assembly, connect the driving and acquisition component to the force application component, the object to be measured, and the measurement component respectively;

[0017] S20, Preparation before measurement. First, adjust the object to be measured to run to the specified test posture, adjust the pressure sensor on the force application seat to be at the force application point to be measured of the object to be measured, and record the distance Lf between the force application point to be measured and the axis of the measured shaft at the same time; make the laser displacement sensor be at the deformation measurement point of the object to be measured, and record the distance Ll between the deformation measurement point and the axis of the measured shaft at the same time. After adjustment, fix the position of the object to be measured; zero the laser displacement sensor and the pressure sensor.

[0018] S30. Data measurement. Adjust the position of the force - applying seat. When the pressure sensor starts to contact the force - applying point to be measured on the object to be measured, collect the value F of the pressure sensor at this time and the data di of the laser displacement sensor at different measurement points. In this way, the relationship between the force and the deformation of the whole object to be measured can be obtained;

[0019] The force - applying seat moves until the applied force reaches 1.5 times the maximum load of the object to be measured. Then, the force - applying seat moves in the reverse direction to gradually reduce the force applied to the object under test until the applied force drops to 0. The force - applying seat moves in the reverse direction to make the pressure sensor installed on the other side of the force - applying seat contact the object under test, and continue to move in the reverse direction until the applied force reaches 1.5 times the maximum load of the object to be measured, and then gradually reduce the force applied to the object under test until the applied force drops to 0. During the whole process, the laser displacement sensor real - time collects the displacement changes of the measured points and synchronously transmits this data to the driving and acquisition component;

[0020] After zeroing the pressure sensor and the laser displacement sensor, repeat the above actions three times;

[0021] S40. Data processing. Calculate the torque T received by the object to be measured through the data F of the force of the pressure sensor collected and the distance Lf between the force - applying point to be measured and the axis of the measured shaft. The calculation formula is as follows:

[0022] T = F * Lf

[0023] Process the data of the laser displacement sensor. Combine the distance Ll between the measurement point and the measured shaft to convert the displacement di of the measurement point into the torsion angle of the measured shaft. The relevant joint torsion angle calculation formula is as follows:

[0024]

[0025] Average - process the data collected three times. In this way, the relationship between the torsion angle and the torque of the joints and connecting rods of the object to be measured can be obtained.

[0026] The difference between an industrial robotic arm stiffness measurement system and method of the present invention and the prior art is that when measuring, the present invention's industrial robotic arm stiffness measurement system and method synchronously collect the applied force and the deformation of the connecting rod, eliminating the problem of asynchronous force and displacement when manually recording the displacement, with high measurement accuracy; realize the adjustment of the force - applying position with three degrees of freedom through the combination of linear modules, and the test is simple and fast; the overall structure is simple, the cost is low, and the reliability is relatively high; it can be applied to the stiffness test of different models, with high applicability.

[0027] The following further describes an industrial robotic arm stiffness measurement system and method of the present invention with reference to the accompanying drawings. Description of the Drawings

[0028] Figure 1 Schematic structural diagram of a stiffness measurement system for an industrial robotic arm according to the present invention;

[0029] Figure 2 Schematic structural diagram of a force application component in a stiffness measurement system for an industrial robotic arm according to the present invention;

[0030] Figure 3 Schematic structural diagram of a measurement component in a stiffness measurement system for an industrial robotic arm according to the present invention;

[0031] Figure 4 Schematic structural diagram of an acquisition component in a stiffness measurement system for an industrial robotic arm according to the present invention;

[0032] Figure 5 Relationship curve between torque and twist angle during the measurement process of a stiffness measurement system for an industrial robotic arm according to the present invention;

[0033] The markings in the figure are as follows: 1 - force application component; 11 - base; 12 - counterweight; 13 - cross-shaped linear module; 14 - force application seat; 15 - pressure sensor; 16 - vertical linear module; 17 - support seat; 2 - object under test; 3 - measurement component; 31 - measurement base; 32 - vertical support column; 33 - pillar fixing clamp; 34 - horizontal support column; 35 - laser displacement sensor; 36 - sensor fixing seat; 4 - drive and acquisition component; 41 - control cabinet; 42 - driver; 43 - data acquisition card; 44 - host computer. Detailed implementation manners

[0034] The following embodiments are used to illustrate the present invention, but do not limit the scope of the present invention.

[0035] Embodiment 1

[0036] As Figure 1 shown, a stiffness measurement system for an industrial robotic arm according to the present invention includes a force application component 1, an object under test 2, a measurement component 3, and a drive and acquisition component 4. The drive and acquisition component 4 is connected to the force application component 1 through a wire harness, and the position control of the end of the force application component 1 is realized by controlling the movement of the linear module in the force application component 1, so as to realize the application of force at the force application point of the object under test 2; the drive and acquisition component 4 communicates with the object under test 2 through a wire harness to realize the control of the pose of the object under test 2; the drive and acquisition component 4 performs data communication with the measurement component 3 in a wired or wireless manner. When the force application component 1 applies a force to the object under test 2, the measurement component 3 will simultaneously collect the displacement amount at the measured point of the object under test 2 and transmit the measurement data to the drive and acquisition component 4 in real time through the established communication.

[0037] As Figure 2As shown in the figure, the force application component includes a base 11, and a number of counterweight blocks 12 are installed on the base 11. The main function of the counterweight blocks 12 is to lower the center of gravity of the force application component 1, so that the force application component 1 is more stable as a whole when applying a force to the object under test 2. The number of counterweight blocks 12 will change with the magnitude of the force applied by the force application component 1 as a whole, so as to achieve the stability of the system.

[0038] A cross-shaped linear module 13 is installed on the base 11. The cross-shaped linear module 13 can provide translational degrees of freedom in the X and Y directions. A support base 17 placed vertically is installed on the slider of the cross-shaped linear module 13. The support base 17 can move with the slider of the cross-shaped linear module 13 to achieve two degrees of freedom of movement in the horizontal plane.

[0039] A vertical linear module 16 is installed on the support base 17. The vertical linear module 16 can provide a degree of freedom of movement in the vertical direction. A force application seat 14 is installed on the slider of the vertical linear module 16. The force application seat 14 can move up and down with the slider of the vertical linear module 16.

[0040] Mounting points for pressure sensors are provided at the upper and lower positions and on both side plates of the force application seat 14, and pressure sensors 15 are installed in the mounting points. When the force application component 1 applies a force to the object under test 2, the pressure sensors 15 at the corresponding positions can collect the magnitude of the applied force.

[0041] The object under test 2 is mainly a robotic arm whose stiffness is to be measured. The object under test 2 is connected to the drive and acquisition component 4 through a wire harness. The drive and acquisition component 4 can control the movement of each joint of the robotic arm of the object under test 2, and thus can achieve the adjustment of the pose of the object under test 2.

[0042] As Figure 3 As shown in the figure, the measurement component 3 includes a measurement base 31, and a vertical support column 32 is fixedly installed on the measurement base 31. A horizontal support column 34 is installed on the vertical support column 32 through a pillar fixing clamp 33. By adjusting the tightness of the pillar fixing clamp 33, the horizontal support column 34 can slide up and down and back and forth along the vertical support column 32.

[0043] A sensor fixing seat 36 is installed at the end of the horizontal support column 34, and a laser displacement sensor 35 is installed on the sensor fixing seat 36. During measurement, the positions of the measurement base 31 and the pillar fixing clamp 33 can be adjusted to make the laser displacement sensor 35 in a more reasonable position and achieve the measurement of the displacement of the measurement point of the object under test 2.

[0044] As Figure 4As shown in the figure, the driving and acquisition component 4 includes a control cabinet 41, a driver 42, a data acquisition card 43, and a host computer 44. The control cabinet 41 is connected to the object to be measured 2 through a cable, and communicates with the host computer 44 by wired or wireless means. The host computer 44 controls the rotation of each axis of the object to be measured 2 by controlling the output current of the control cabinet 41, thereby realizing the adjustment of the pose of the object to be measured 2.

[0045] The driver 42 communicates and controls with the cross-shaped linear module 13 and the vertical linear module 16 in the force application component 1 through a wire harness, and also communicates with the host computer 44 by wired or wireless means. The host computer 44 controls the positions of the sliders of the cross-shaped linear module 13 and the vertical linear module 16 through the driver 42.

[0046] On the one hand, the data acquisition card 43 communicates with the pressure sensor 15 in the force application component 1 by wired or wireless means. On the other hand, it communicates with the laser displacement sensor 35 in the measurement component by wired or wireless means, and can transmit the data collected by the two sensors to the host computer 44 in real time. The host computer 44 calculates the stiffness of the measured link and the measured joint of the object to be measured 2 based on the data of the pressure sensor 15 and the laser displacement sensor 35, combined with the distance from the force application point to the measurement axis and the distance from the measurement point to the measurement axis.

[0047] The working principle of an industrial robot arm stiffness measurement system of the present invention is as follows.

[0048] 1) System assembly and debugging. First, install the object to be measured 2 on the base, connect the control cabinet 41 to the object to be measured 2 through a wire harness. The host computer 44 can communicate with the control cabinet 41 by wired or wireless means and send instructions to the control cabinet 41 to realize the adjustment of the pose of the object to be measured 2.

[0049] Move the force application component 1 near the object to be measured 2, and adjust the universal wheel adjustment block under the base 11 to make the base 11 in a locked and fixed state with the ground. Dynamically increase or decrease the number of counterweight blocks 12 according to the magnitude of the force required to be applied to the object to be measured 2 and the height of the applied force, so that the force application component 1 can always maintain a stable state when applying force to the object to be measured 2.

[0050] Connect the driver 42 to the cross-shaped linear module 13 and the vertical linear module 16 through a wire harness. The driver 42 adjusts the positions of the sliders of the cross-shaped linear module 13 and the vertical linear module 16 by outputting different currents; the driver 42 can also communicate with the host computer 44 by wired or wireless means. The host computer 44 controls the positions of the sliders of the cross-shaped linear module 13 and the vertical linear module 16 by controlling the current output of the driver 42, thereby realizing the adjustment of the position of the support base 17.

[0051] Install the pressure sensor 15 on the support base 17 according to the direction of the applied force, and connect the pressure sensor 15 to the data acquisition card 43 by wired or wireless means. During the measurement process, the data acquisition card 43 can collect the force data on the pressure sensor in real time.

[0052] Place the measurement component 3 near the object under test 2. Install the laser displacement sensor 35 on the sensor fixing base 36. The laser displacement sensor 35 can communicate with the data acquisition card 43 by wired or wireless means, and can feedback the displacement of the acquisition point to the data acquisition card 43 in real time.

[0053] 2) Preparation work before measurement. During measurement, first use the host computer 44 to send a motion command to the control cabinet 41 to control the object under test 2 to run to the specified test posture. After reaching the position, control the driver 42 to enable the measurement object 2 to be in a power-off holding state. Use the host computer 44 to send a motion command to the driver 42 to control the slider of the cross-shaped linear module 13 to move forward, backward, left, and right and control the slider of the vertical linear module 16 to move up and down, so that the pressure sensor 15 installed on the force application seat 14 is exactly at the force application point to be measured of the object under test 2, and at the same time record the distance Lf between the force application point to be measured and the axis of the measured shaft. Loosen the pillar fixing clamp 33, adjust the height and horizontal position of the horizontal support pillar 34 so that the laser displacement sensor 35 is at the deformation measurement point of the object under test 2, and at the same time record the distance Ll between the deformation measurement point and the axis of the measured shaft. After adjustment, lock the pillar fixing clamp 33. In the actual measurement process, there can be multiple measurement components 3. Each measurement component 3 can collect different positions on the object under test 2, and analyze the link stiffness between the two points to be measured by comparing the deformation amounts at different positions. Use the host computer 44 to zero the laser displacement sensor 35 and the pressure sensor 15. In this way, all the preparation work before measurement is completed.

[0054] 3) Data measurement. When starting the measurement, first use the host computer 44 to send a motion command to the driver 42 to make the cross-shaped linear module 13 or the vertical linear module 16 move along a straight line. When the pressure sensor 15 at the end of the force application component 1 starts to contact the force application point to be measured of the object under test 2, the pressure sensor 15 will start to exert a force on the object under test 2. Use the data acquisition card 43 to collect the force value F of the pressure sensor 15 at this time and the data di of the laser displacement sensor 35 at different measurement points. In this way, the relationship between the overall force and the deformation amount of the object under test 2 can be obtained.

[0055] The host computer 44 continues to control the forward movement of the force application component 1 to continuously increase the applied force until the applied force reaches 1.5 times the maximum load of the object to be measured, and then controls the reverse movement of the force application component 1 to gradually reduce the force applied to the object to be measured 2 until the applied force drops to 0. The host computer 44 controls the reverse movement of the force application component 1 to make the pressure sensor installed on the other side of the force application seat 14 contact the object to be measured 2, and controls the force application component 1 to continue to move in the reverse direction to continuously increase the force applied to the object to be measured 2 until the applied force reaches 1.5 times the maximum load of the object to be measured, and then controls the forward movement of the force application component 1 to gradually reduce the force applied to the object to be measured 2 until the applied force drops to 0. During the whole process, the laser displacement sensor 35 real-time collects the displacement change of the measured point and synchronously transmits the data to the data acquisition card 43. After clearing the pressure sensor 15 and the laser displacement sensor 35, repeat the above actions three times and save the collected data on the host computer 44.

[0056] 4) Data processing. Use the host computer 44 to process the data collected above. First, the torque T received by the object to be measured 2 can be calculated through the force data F of the pressure sensor 15 collected and the distance Lf between the force application point to be measured and the axis of the object to be measured. The relevant calculation formula is as follows.

[0057] T = F * Lf

[0058] Process the data of the laser displacement sensor 35. Combine the distance Ll between the measurement point and the object to be measured axis to convert the displacement di of the measurement point into the torsion angle of the object to be measured axis. The relevant joint torsion angle calculation formula is as follows.

[0059]

[0060] Average process the data collected three times, so that the relationship between the torsion angle of the joints and connecting rods of the object to be measured 2 and the torque received can be obtained, and it can be plotted into a chart, as Figure 4 shown. When the point collected by the laser displacement sensor 35 is the end of the object to be measured 2, the plotted curve reflects the stiffness of the measured joint and connecting rod; when the point collected by the laser displacement sensor 35 is relatively close to the object to be measured axis, the plotted curve can basically represent the transmission stiffness of the joint. The difference in torsion angle between the two displacement collection points within the force application point can be considered as the stiffness of the connecting rod in this section. In addition, we can also obtain the backlash of the entire measured joint through the torque-torsion angle curve. The above data can provide data support for subsequent motion control and servo control.

[0061] Embodiment 2

[0062] This embodiment provides an industrial robotic arm stiffness measurement method for realizing the stiffness measurement of the connecting rods and joints of the robotic arm to be measured.

[0063] A method for measuring the stiffness of an industrial robotic arm according to the present invention comprises the following steps:

[0064] S10. System assembly: Connect the driving and acquisition components 4 to the force application component 1, the object to be measured 2, and the measurement component 3 respectively. Specifically, connect the host computer 44 to the control cabinet 41 and the driver 42 respectively, connect the control cabinet 41 to the object to be measured 2, and connect the driver 42 to the cross-shaped linear module 13 and the vertical linear module 16 respectively; Move the force application component 1 to the vicinity of the object to be measured 2 and fix it, and adjust the quantity and position of the counterweight 12 to keep the force application component 1 stable; Install the pressure sensor 15 on the support base 17, install the laser displacement sensor 35 on the sensor fixing base 36, and the data acquisition card 43 communicates with the pressure sensor 15 and the laser displacement sensor 35 respectively for data.

[0065] S20. Preparation before measurement: First, use the host computer 44 to send a motion command to the control cabinet 41 to control the object to be measured 2 to run to the specified test posture. After arriving, control the driver 42 to enable the measurement object 2 to be in a power-off hold state; Use the host computer 44 to send a motion command to the driver 42 to control the slider of the cross-shaped linear module 13 to move forward, backward, left, and right and control the slider of the vertical linear module 16 to move up and down, so that the pressure sensor 15 installed on the force application seat 14 is exactly at the force application point to be measured of the object to be measured 2, and at the same time record the distance Lf between the force application point to be measured and the axis of the measured shaft; Loosen the pillar fixing clamp 33, adjust the height and horizontal position of the horizontal support pillar 34 so that the laser displacement sensor 35 is at the deformation measurement point of the object to be measured 2, and at the same time record the distance Ll between the deformation measurement point and the axis of the measured shaft. After adjustment, lock the pillar fixing clamp 33; Use the host computer 44 to zero the laser displacement sensor 35 and the pressure sensor 15. In this way, all the preparation work before measurement is completed.

[0066] During the actual measurement process, there can be multiple measurement components 3. Each measurement component 3 can collect different positions on the object to be measured 2, and analyze the link stiffness between two points to be measured by comparing the deformation amounts at different positions.

[0067] S30. Data measurement: First, use the host computer 44 to send a motion command to the driver 42 to make the cross-shaped linear module 13 or the vertical linear module 16 move along a straight line. When the pressure sensor 15 at the end of the force application component 1 starts to contact the force application point to be measured of the object to be measured 2, the pressure sensor 15 will start to exert a force on the object to be measured 2. Use the data acquisition card 43 to collect the force value F of the pressure sensor 15 at this time and the data di of the laser displacement sensor 35 at different measurement points. In this way, the relationship between the overall force and the deformation amount of the object to be measured 2 can be obtained;

[0068] The host computer 44 continues to control the forward movement of the force application component 1 to continuously increase the applied force until the applied force reaches 1.5 times the maximum load of the body under test, and then controls the reverse movement of the force application component 1 to gradually reduce the force applied to the body under test 2 until the applied force drops to 0; the host computer 44 controls the reverse movement of the force application component 1 to make the pressure sensor installed on the other side of the force application seat 14 contact the body under test 2, and controls the force application component 1 to continue to move in the reverse direction to continuously increase the force applied to the body under test 2 until the applied force reaches 1.5 times the maximum load of the body under test, and then controls the forward movement of the force application component 1 to gradually reduce the force applied to the body under test 2 until the applied force drops to 0. During the whole process, the laser displacement sensor 35 real-time collects the displacement changes of the measured points and synchronously transmits the data to the data acquisition card 43;

[0069] After clearing the pressure sensor 15 and the laser displacement sensor 35, repeat the above actions three times and save the collected data on the host computer 44.

[0070] S40, data processing, use the host computer 44 to process the above collected data. First, the torque T received by the body under test 2 can be calculated by the force data F of the pressure sensor 15 and the distance Lf between the force application point to be measured and the axis of the body under test. The relevant calculation formula is as follows,

[0071] T = F * Lf

[0072] Process the data of the laser displacement sensor 35. Combine the distance Ll between the measurement point and the body under test axis to convert the displacement di of the measurement point into the torsion angle of the body under test axis. The relevant joint torsion angle calculation formula is as follows,

[0073]

[0074] Perform average processing on the data collected three times, so that the relationship between the torsion angle and the torque of the joints and connecting rods of the body under test 2 can be obtained, and it can be plotted into a graph, such as Figure 4 shown.

[0075] When the point collected by the laser displacement sensor 35 is the end of the body under test 2, the drawn curve reflects the stiffness of the measured joint and connecting rod; when the point collected by the laser displacement sensor 35 is closer to the body under test axis, the drawn curve basically represents the transmission stiffness of the joint. The difference in the torsion angle between the two displacement collection points within the force application point can be considered as the stiffness of the connecting rod in this section. In addition, we can also obtain the backlash of the entire measured joint through the torque-torsion angle curve. The above data can provide data support for subsequent motion control and servo control.

[0076] When the industrial robot arm stiffness measurement system and method of the present invention are in measurement, the applied force and the deformation of the connecting rod are synchronously collected, eliminating the problem of asynchronous force and displacement when manually recording the displacement, and having high measurement accuracy; all controls are realized through the upper computer, the whole measurement logic is simple, and one-key measurement can be realized through programming, greatly reducing the amount of manual operation and the operation difficulty; the adjustment of the force application position with three degrees of freedom is realized through the matching of the linear module, and the test is simple and fast; the overall structure is simple, the cost is low, and the reliability is high; it can be applied to the stiffness test of different models, and the applicability is high.

[0077] Although the present invention has been described in detail with general descriptions and specific embodiments above, based on the present invention, some modifications or improvements can be made, which are obvious to those skilled in the art. Therefore, these modifications or improvements made without departing from the spirit of the present invention all fall within the scope of protection required by the present invention.

Claims

1. An industrial robotic arm stiffness measurement system, characterized in that: It includes a force - applying component, a body to be measured, a measurement component, and a driving and acquisition component. The driving and acquisition component is respectively connected to the force - applying component, the body to be measured, and the measurement component. The force - applying component includes a number of linear modules. The linear module drives a force - applying seat to apply a force to the body to be measured. Pressure sensors are arranged around the force - applying seat. The measurement component includes a laser displacement sensor, which is used to collect the displacement of the measured point on the body to be measured. The data of the applied force and the displacement can be transmitted to the driving and acquisition component.

2. The stiffness measurement system of an industrial robotic arm according to claim 1, wherein: The force - applying component includes a base, and a number of counterweights are arranged on the base.

3. The stiffness measurement system of an industrial robotic arm according to claim 1, wherein: The linear module includes a cross - shaped linear module and a vertical linear module. The cross - shaped linear module is arranged on the base of the force - applying component. A support seat is arranged on the slider of the cross - shaped linear module. The vertical linear module is arranged on the support seat. The force - applying seat is arranged on the slider of the vertical linear module.

4. The stiffness measurement system of an industrial robotic arm according to claim 1, characterized in that: Pressure sensors are arranged at the upper and lower parts and on both side plates of the force - applying seat.

5. The stiffness measurement system of an industrial robotic arm according to claim 1, characterized in that: The measurement component includes a vertical support column. A horizontal support column is installed on the vertical support column through a pillar fixing clip. The laser displacement sensor is arranged on the horizontal support column.

6. The stiffness measurement system of an industrial robotic arm according to claim 1, characterized in that: The driving and acquisition component includes a control cabinet, a driver, and a data acquisition card.

7. An industrial robotic arm stiffness measurement system according to claim 6, characterized in that: The control cabinet is connected to the body to be measured and is used to control the posture of the body to be measured. The driver can communicate with the linear module in the force - applying component.

8. An industrial robotic arm stiffness measurement system according to claim 6, characterized in that: It further includes a host computer, which can communicate with the control cabinet and the driver respectively.

9. The stiffness measurement system of an industrial robotic arm according to claim 6, characterized in that: The data acquisition card can collect the data of the pressure sensor and the laser displacement sensor respectively.

10. A method for measuring the stiffness of an industrial robotic arm, which uses the industrial robotic arm stiffness measurement system described in any one of claims 1-9, characterized in that: It includes the following steps: S10, System assembly. Connect the driving and acquisition component to the force - applying component, the body to be measured, and the measurement component respectively. S20, Preparation before measurement. First, adjust the body to be measured to run to the specified test posture. Adjust the pressure sensor on the force - applying seat to be at the force - applying point to be measured of the body to be measured, and record the distance Lf between the force - applying point to be measured and the axis of the measured shaft at the same time. Make the laser displacement sensor be at the deformation measurement point of the body to be measured, and record the distance Ll between the deformation measurement point and the axis of the measured shaft at the same time. After adjustment, fix the position of the body to be measured. Zero the laser displacement sensor and the pressure sensor. S30, Data measurement. Adjust the position of the force - applying seat. When the pressure sensor starts to contact the force - applying point to be measured of the body to be measured, collect the value F of the pressure sensor at this time and the data di of the laser displacement sensor at different measurement points. In this way, the relationship between the overall force and deformation of the body to be measured can be obtained. The force - applying seat moves until the applied force reaches 1.5 times the maximum load of the body to be measured. Then the force - applying seat moves in the reverse direction to gradually reduce the force applied to the body to be measured until the applied force drops to 0. The force - applying seat moves in the reverse direction to make the pressure sensor installed on the other side of the force - applying seat contact the body to be measured, and continue to move in the reverse direction until the applied force reaches 1.5 times the maximum load of the body to be measured, and then gradually reduce the force applied to the body to be measured until the applied force drops to 0. During the whole process, the laser displacement sensor continuously collects the displacement change of the measured point and synchronously transmits the data to the driving and acquisition component. After zeroing the pressure sensor and the laser displacement sensor, repeat the above actions three times. S40. Data processing: Calculate the torque T received by the object to be measured based on the force data F of the pressure sensor and the distance Lf between the force application point to be measured and the axis of the measured shaft. The calculation formula is as follows: T = F * Lf Process the data of the laser displacement sensor. Combine the distance Ll between the measurement point and the measured shaft, and convert the displacement di of the measurement point into the torsion angle of the measured shaft. The calculation formula for the relevant joint torsion angle is as follows: Average the data collected three times, and thus the relationship between the torsion angle of the joints and connecting rods of the object to be measured and the torque received can be obtained.

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