A robot six-dimensional force sensor online calibration device and active drive calibration method

Abstract

The present application relates to the technical field of robot six-dimensional force sensor calibration, and in particular to a robot six-dimensional force sensor online calibration device and an active drive calibration method. Among them, a robot six-dimensional force sensor online calibration device includes a six-degree-of-freedom platform and a control system, the six-degree-of-freedom platform is used to place the six-dimensional force sensor and is electrically connected to the control system, and the control system is used to load force to the six-degree-of-freedom platform and calibrate the force and torque of the six-dimensional force sensor. The present application has the following effects: the robot and the six-dimensional force sensor are placed on one side of the calibration device, and then the six-dimensional force sensor is placed on the six-degree-of-freedom platform. The control system loads force to the six-degree-of-freedom platform and calibrates the force and torque of the six-dimensional force sensor. It can realize the online calibration of the six-dimensional force sensor without stopping the normal operation of the robot, thereby improving the calibration efficiency of the six-dimensional force sensor.

Description

Technical Field

[0001] The present application relates to the technical field of robot six-dimensional force sensor calibration, and in particular to an online calibration device for a robot six-dimensional force sensor and an active drive calibration method. Background Art

[0002] The six-axis force sensor is a key component for the robot to achieve force perception. It can measure the force and torque of the robot actuator in three directions in real time. However, due to factors such as the assembly of the six-axis force sensor on the robot and temperature changes in the working environment, even if the six-axis force sensor is calibrated at the factory, there will still be measurement errors during specific use. Therefore, periodic online calibration of the six-axis force sensor is the key to improving the perception accuracy of the robot's force system.

[0003] At present, the calibration of robot six-axis force sensors is mostly done offline, that is, the six-axis force sensors are disassembled and sent to the calibration laboratory for calibration. This offline method can calibrate the individual six-axis force sensors with high precision.

[0004] However, with offline calibration, the process of sensor disassembly and calibration is time-consuming, causing the robot to stop working for a long time, resulting in low calibration efficiency. Summary of the invention

[0005] In order to improve the calibration efficiency of a six-dimensional force sensor, the present application provides an online calibration device for a robot six-dimensional force sensor and an active drive calibration method.

[0006] In the first aspect, the present application provides a robot six-axis force sensor online calibration device, which adopts the following technical solution: it includes a six-degree-of-freedom platform and a control system, the six-degree-of-freedom platform is used to place the six-axis force sensor and is electrically connected to the control system, and the control system is used to load force to the six-degree-of-freedom platform and calibrate the force and torque of the six-axis force sensor.

[0007] By adopting the above technical solution, the robot and the six-dimensional force sensor are placed on one side of the calibration device, and then the six-dimensional force sensor is placed on a six-degree-of-freedom platform. The control system loads force on the six-degree-of-freedom platform and calibrates the force and torque of the six-dimensional force sensor. The six-dimensional force sensor can be calibrated online without stopping the normal operation of the robot, thereby improving the calibration efficiency of the six-dimensional force sensor.

[0008] Preferably, the six-degree-of-freedom platform includes an upper moving platform, a lower static platform and a branch chain, the branch chain is connected between the upper moving platform and the lower static platform, the control system realizes force loading by controlling the branch chain and thereby drives the displacement change of the upper moving platform, and a unidimensional force sensor is provided on the branch chain.

[0009] By adopting the above technical solution, the control system calculates the length adjustment amount of the branch chain according to the preset force-displacement control algorithm, and sends the length adjustment amount to the branch chain. The branch chain controls the length change of the branch chain according to the received length adjustment amount. After the spatial posture is fixed, the force value of the one-dimensional force sensor is decomposed and synthesized and compared with the force and torque value of the six-dimensional force sensor, so as to obtain the error of the force and torque value of the six-dimensional force sensor.

[0010] Preferably, six branch chains are provided, one end of the branch chain is used for rotationally connecting to the lower surface of the upper moving platform, and the other end of the branch chain is used for rotationally connecting to the upper surface of the lower static platform, the six branch chains are arranged at intervals along the circumference of the upper moving platform, and the one-dimensional force sensor is provided on each of the six branch chains.

[0011] By adopting the above technical solution, six branches are provided with unidimensional force sensors on all six branches, thereby improving the calibration accuracy and the stability of the structure.

[0012] Preferably, the branch chains are grouped in two, the branch chains are arranged at an angle, the spacing between the upper ends of the two branch chains in the same group is smaller than the spacing between the lower ends, the three groups of branch chains are arranged at equal angles along the upper moving platform, and the radial distances from the upper ends of the three groups of branch chains to the center of the upper moving platform are smaller than the radial distances from the lower ends of the three groups of branch chains to the center of the lower static platform.

[0013] By adopting the above technical solution, the distance from the upper end of the branch chain to the center axis of the upper moving platform is smaller than the distance from the lower end of the branch chain to the lower static platform and the center axis, so that the calibration equipment forms a structure that is small at the top and large at the bottom, thereby improving the structural stability of the calibration device and ensuring the calibration accuracy to a certain extent.

[0014] Preferably, the branch chain is telescopically arranged along a length direction parallel to the branch chain through the control system.

[0015] By adopting the above technical solution, the control system controls the branch chain to realize the loading of force on the upper moving platform. The control system calculates the length adjustment amount of the branch chain according to the preset force-displacement control algorithm, and sends the length adjustment amount to the branch chain. The branch chain controls the length change of multiple branches according to the received length adjustment amount, and generates stress through strain.

[0016] Preferably, the control system controls the six branches to be telescopically adjusted separately.

[0017] By adopting the above technical solution, the forces of the six unidimensional force sensors will be decomposed and then synthesized in the directions of six degrees of freedom. The separate telescopic adjustment of the six branches can cope with different working conditions and improve the calibration accuracy.

[0018] Preferably, the branch chain includes a flexible connecting member and a driving member, the driving member is used to drive the branch chain to extend and retract, the driving member is electrically connected to the control system, the driving member and the one-dimensional force sensor are arranged at intervals along the length direction of the branch chain, and the flexible connecting member is arranged on opposite sides of the driving member and the one-dimensional force sensor.

[0019] By adopting the above technical solution, the control system controls the operation of the driving member, the driving member drives the extension and contraction of the branch chain, and the flexible connecting member bears the load.

[0020] Preferably, the flexible connector includes a connecting disc and an elastic sheet, wherein at least one elastic sheet is provided and at least two connecting discs are provided, the connecting discs and the elastic sheets are connected in sequence in an alternating manner, each connecting disc is coaxially arranged, the elastic sheet is arranged in a direction perpendicular to the disc surface of the connecting disc, the length direction of the elastic sheet is arranged radially along the connecting disc, and adjacent elastic sheets are cross-staggered.

[0021] By adopting the above technical solution, the flexible connector bears and transmits the loading load, reducing the burden on other structural parts of the branch chain. The cross-staggered elastic sheets minimize the mutual influence between multi-directional force components and improve the calibration accuracy.

[0022] In a second aspect, the present application provides an active drive calibration method, which adopts the following technical solution:

[0023] An active drive calibration method is implemented by using a robot six-dimensional force sensor online calibration device according to any one of claims 1 to 8, comprising the following steps:

[0024] S0: Fixed installation robot six-dimensional force sensor online calibration device;

[0025] S1: Connect the upper moving platform in series with the robot's six-dimensional force sensor;

[0026] S2: Initialize the six-degree-of-freedom platform and control system, set the initial position of the upper moving platform, the initial zero points of the six single-axis force sensors, and the initial zero point of the six-axis force sensor;

[0027] S3: Set the calibration point data required, which is the force or torque in a certain direction, or the synthetic force / torque vector;

[0028] S4: The control system generates a set of force and displacement adjustment values ​​according to a preset force control algorithm, and sends the length adjustment values ​​to the branch chain;

[0029] S5: The branch chain controls the length change of the six branch chains according to the received length adjustment amount, and drives the upper moving platform to move;

[0030] S6: Six uniaxial force sensors measure the force on the upper moving platform in real time and send the measured force data to the control system;

[0031] S7: The control system solves the forces and moments of the six degrees of freedom according to the spatial position of the platform, and calculates the forces that need to be further loaded according to the preset calibration points.

[0032] By adopting the above technical solution, the control system controls the branch chain to realize the loading of force on the upper moving platform. The control system calculates the length adjustment amount of the branch chain according to the preset force-displacement control algorithm, and sends the length adjustment amount to the branch chain. The branch chain controls the length change of multiple branches according to the received length adjustment amount. The branch chain then solves the angle change according to the length change. The force values ​​of multiple single-dimensional force sensors are decomposed and synthesized and then compared with the force and torque values ​​of the six-dimensional force sensor, so as to obtain the errors of the force and torque values ​​of the six-dimensional force sensor.

[0033] Preferably, the control system determines whether the loaded force value satisfies a preset calibration point convergence condition, and ends the calibration process if it does, and returns to step S4 if it does not.

[0034] By adopting the above technical solution, if the preset calibration point convergence condition is not met, the control system regenerates the adjustment amount and calibrates again, thereby improving the calibration accuracy.

[0035] In summary, the present application includes at least one of the following beneficial technical effects:

[0036] 1. Without stopping the normal operation of the robot, the online calibration of the six-dimensional force sensor is realized to improve the calibration efficiency of the six-dimensional force sensor;

[0037] 2. The force values ​​of multiple single-dimensional force sensors are decomposed and synthesized, and then compared with the force and torque values ​​of the six-dimensional force sensor to obtain the errors of the force and torque values ​​of the six-dimensional force sensor. BRIEF DESCRIPTION OF THE DRAWINGS

[0038] Figure 1 It is a schematic diagram of the overall structure of a robot six-dimensional force sensor online calibration device of the present application, and is a schematic diagram of the robot six-dimensional force sensor in the online calibration state;

[0039] Figure 2 It is a schematic diagram of the overall structure of a robot six-dimensional force sensor online calibration device of the present application, which is a schematic diagram of the robot and the six-dimensional force sensor not shown;

[0040] Figure 3 yes Figure 2 A partial enlarged schematic diagram of part A;

[0041] Figure 4It is a schematic diagram of the steps of an active drive calibration method of the present application.

[0042] Explanation of the reference numerals in the accompanying drawings: 110, six-degree-of-freedom platform; 1101, upper moving platform; 1102, lower static platform; 1103, branch chain; 111, six-dimensional force sensor; 112, robot; 113, weight-reducing hole; 114, one-dimensional force sensor; 120, flexible connector; 1201, connecting disc; 1202, elastic sheet; 130, driving member. DETAILED DESCRIPTION

[0043] The present application is further described in detail below in conjunction with the accompanying drawings.

[0044] An embodiment of the present application discloses an online calibration device for a robot's six-dimensional force sensor.

[0045] refer to Figure 1 , Figure 2 A robot six-dimensional force sensor online calibration device includes a six-degree-of-freedom platform 110 and a control system. The six-degree-of-freedom platform 110 is used to place a six-dimensional force sensor 111 and is electrically connected to the control system. The control system is used to load force to the six-degree-of-freedom platform 110 and calibrate the force and torque of the six-dimensional force sensor 111. The robot 112 and the six-dimensional force sensor 111 are placed on one side of the calibration device, and then the six-dimensional force sensor 111 is placed on the six-degree-of-freedom platform 110. The control system loads force to the six-degree-of-freedom platform 110 and calibrates the force and torque of the six-dimensional force sensor 111. The six-dimensional force sensor 111 can be calibrated online without stopping the normal operation of the robot 112, thereby improving the calibration efficiency of the six-dimensional force sensor 111.

[0046] Specifically, the six-degree-of-freedom platform 110 includes an upper moving platform 1101, a lower static platform 1102 and a branch chain 1103, the branch chain 1103 is connected between the upper moving platform 1101 and the lower static platform 1102, the control system realizes the force loading by controlling the branch chain 1103 and then drives the displacement change of the upper moving platform 1101, the upper moving platform 1101 and the lower static platform 1102 are coaxially arranged in the vertical direction, the upper moving platform 1101 is located above the lower static platform 1102, and the upper moving platform 1101 is used to be connected in series with the detected six-dimensional force sensor 111. In this embodiment The projection surfaces of the upper moving platform 1101 and the lower static platform 1102 in the vertical direction are both equilateral triangles, and the projection surface area of ​​the upper moving platform 1101 along the vertical direction is smaller than the projection surface area of ​​the lower static platform 1102 along the vertical direction, so that the calibration equipment forms a structure that is small on the top and large on the bottom, thereby improving the structural stability of the calibration device and ensuring the calibration accuracy to a certain extent; a weight-reducing hole 113 is penetrated along the vertical direction on the lower static platform 1102, which not only saves the production material cost, but also realizes the lightweight design of the calibration device, and the weight-reducing hole 113 and the lower static platform 1102 are coaxially arranged.

[0047] Furthermore, six branch chains 1103 are provided, one end of the branch chain 1103 is used for rotationally connecting with the lower surface of the upper moving platform 1101, and the other end of the branch chain 1103 is used for rotationally connecting with the upper surface of the lower static platform 1102. The six branch chains 1103 are arranged at intervals along the circumference of the upper moving platform 1101, and the six branch chains 1103 are each provided with a one-dimensional force sensor 114. The control system calculates the length adjustment amount of the branch chain 1103 according to a preset force-displacement control algorithm, and sends the length adjustment amount to the branch chain 1103. The branch chain 1103 controls the length change of the branch chain 1103 according to the received length adjustment amount. After the spatial posture is fixed, the force value of the one-dimensional force sensor 114 is decomposed and synthesized and compared with the force and torque values ​​of the six-dimensional force sensor 111, so as to obtain the errors of the force and torque values ​​of the six-dimensional force sensor 111.

[0048] Two branch chains 1103 form a group, and the branch chains 1103 are arranged at an angle. The distance between the upper ends of the two branch chains 1103 in the same group is smaller than the distance between the lower ends. The three groups of branch chains 1103 are arranged at equal angles along the upper moving platform 1101. The radial distance from the upper ends of the three groups of branch chains 1103 to the center of the upper moving platform 1101 is smaller than the radial distance from the lower ends of the three groups of branch chains 1103 to the center of the lower static platform 1102, so that the calibration equipment forms a structure with a small top and a large bottom, which improves the structural stability of the calibration device and ensures the calibration accuracy to a certain extent.

[0049] refer to Figure 2 , Figure 3 Specifically, the branch chain 1103 includes a flexible connecting member 120 and a driving member 130. The driving member 130 is used to drive the branch chain 1103 to retract and retract. The driving member 130 is electrically connected to the control system. The branch chain 1103 can be retracted and retracted along a length direction parallel to the branch chain 1103 through the control system. The driving member 130 and the one-dimensional force sensor 114 are arranged at intervals along the length direction of the branch chain 1103. The driving member 130 and the one-dimensional force sensor 114 are provided with flexible connecting members 120 on opposite sides thereof, and the control system controls the six branches 1103 to retract and retract separately. In this embodiment, the driving member 130 adopts a high-precision linear motor.

[0050] The flexible connector 120 includes a connecting disk 1201 and an elastic sheet 1202. There is at least one elastic sheet 1202 and at least two connecting disks 1201. The connecting disks 1201 and the elastic sheets 1202 are connected alternately in sequence. Each connecting disk 1201 is coaxially arranged. The elastic sheet 1202 is arranged in a direction perpendicular to the disk surface of the connecting disk 1201. The length direction of the elastic sheet 1202 is arranged radially along the connecting disk 1201. Adjacent elastic sheets 1202 are cross-staggered. The flexible connector 120 bears and transmits the loading load, reducing the burden on other structural parts of the branch chain 1103. The cross-staggered elastic sheets 1202 reduce the mutual influence between multi-directional force components as much as possible, thereby improving the calibration accuracy. In this embodiment, each flexible connector 120 includes three connecting disks 1201 and two elastic sheets 1202.

[0051] The implementation principle of a robot six-dimensional force sensor online calibration device in an embodiment of the present application is: the control system controls the branch chain 1103 to realize the force loading on the upper moving platform 1101, the control system calculates the length adjustment amount of the branch chain 1103 according to the preset force-displacement control algorithm, and sends the length adjustment amount to the branch chain 1103, the branch chain 1103 controls the length change of multiple branches 1103 according to the received length adjustment amount, and the branch chain 1103 then solves the angle change according to the length change, and decomposes and synthesizes the force values ​​of multiple single-dimensional force sensors 114 and compares them with the force and torque values ​​of the six-dimensional force sensor 111 to obtain the errors of the force and torque values ​​of the six-dimensional force sensor 111; if the preset calibration point convergence condition is not met, the control system regenerates the adjustment amount and calibrates again to improve the calibration accuracy.

[0052] The embodiment of the present application also discloses an active drive calibration method.

[0053] refer to Figure 2 , Figure 4 An active drive calibration method is implemented by applying the above-mentioned robot six-dimensional force sensor online calibration device, comprising the following steps:

[0054] S0: an online calibration device for the six-dimensional force sensor 111 of the fixedly mounted robot 112;

[0055] S1: Connect the upper moving platform 1101 and the six-dimensional force sensor 111 of the robot 112 in series;

[0056] S2: Initialize the six-degree-of-freedom platform 110 and the control system, set the initial position of the upper moving platform 1101, the initial zero points of the six one-dimensional force sensors 114 and the initial zero point of the six-dimensional force sensor 111;

[0057] S3: Set the calibration point data required, which is the force or torque in a certain direction, or the synthetic force / torque vector;

[0058] S4: The control system generates a set of force and displacement adjustment values ​​according to a preset force control algorithm, and sends the length adjustment values ​​to the branch chain 1103;

[0059] S5: The branch chain 1103 controls the length change of the six branch chains 1103 according to the received length adjustment amount, and drives the upper moving platform 1101 to move;

[0060] S6: six unidimensional force sensors 114 measure the force exerted on the upper moving platform 1101 in real time, and send the measured force data to the control system;

[0061] S7: The control system solves the forces and moments of the six degrees of freedom according to the spatial position of the platform, and calculates the forces that need to be further loaded according to the preset calibration points.

[0062] Furthermore, the control system determines whether the loaded force value satisfies a preset calibration point convergence condition, and if so, ends the calibration process; if not, returns to step S4.

[0063] The embodiments of this specific implementation method are all preferred embodiments of the present application, and are not intended to limit the protection scope of the present application. Therefore, all equivalent changes made based on the structure, shape, and principle of the present application should be included in the protection scope of the present application.

Claims

1. A robot six-dimensional force sensor online calibration device, characterized in that: The device comprises a six-degree-of-freedom platform (110) and a control system, wherein the six-degree-of-freedom platform (110) is used to place a six-dimensional force sensor (111) and is electrically connected to the control system, and the control system is used to load force onto the six-degree-of-freedom platform (110) and calibrate the force and torque of the six-dimensional force sensor (111); The six-degree-of-freedom platform (110) comprises an upper moving platform (1101), a lower static platform (1102) and a branch chain (1103); the branch chain (1103) is connected between the upper moving platform (1101) and the lower static platform (1102); the control system controls the branch chain (1103) to load a force and thereby drives the displacement change of the upper moving platform (1101); and a uniaxial force sensor (114) is provided on the branch chain (1103); The branch chain (1103) comprises a flexible connecting member (120) and a driving member (130), wherein the driving member (130) is used to drive the branch chain (1103) to extend and retract, the driving member (130) is electrically connected to the control system, the driving member (130) and the one-dimensional force sensor (114) are arranged at intervals along the length direction of the branch chain (1103), and the flexible connecting member (120) is arranged on opposite sides of the driving member (130) and the one-dimensional force sensor (114); The flexible connecting member (120) comprises a connecting disk (1201) and an elastic sheet (1202), at least one elastic sheet (1202) is provided, and at least two connecting disks (1201) are provided, the connecting disks (1201) and the elastic sheets (1202) are sequentially staggered and connected, each connecting disk (1201) is coaxially arranged, the elastic sheet (1202) is arranged in a direction perpendicular to the disk surface of the connecting disk (1201), the length direction of the elastic sheet (1202) is arranged radially along the connecting disk (1201), and adjacent elastic sheets (1202) are arranged in a cross-staggered manner.

2. The robot six-dimensional force sensor online calibration device according to claim 1, characterized in that: There are six branch chains (1103), one end of each branch chain (1103) is used for rotationally connecting to the lower surface of the upper moving platform (1101), and the other end of each branch chain (1103) is used for rotationally connecting to the upper surface of the lower static platform (1102). The six branch chains (1103) are arranged at intervals along the circumference of the upper moving platform (1101), and the one-dimensional force sensor (114) is arranged on each of the six branch chains (1103).

3. The robot six-dimensional force sensor online calibration device according to claim 2, characterized in that: The branch chains (1103) are arranged in groups of two, and the branch chains (1103) are arranged at an angle. The distance between the upper ends of the two branch chains (1103) in the same group is smaller than the distance between the lower ends. The three groups of branch chains (1103) are arranged at equal angles along the upper moving platform (1101), and the radial distances from the upper ends of the three groups of branch chains (1103) to the center of the upper moving platform (1101) are smaller than the radial distances from the lower ends of the three groups of branch chains (1103) to the center of the lower static platform (1102).

4. The robot six-dimensional force sensor online calibration device according to claim 3, characterized in that: The branch chain (1103) is telescopically arranged along a length direction parallel to the branch chain (1103) through the control system.

5. The robot six-dimensional force sensor online calibration device according to claim 4, characterized in that: The control system controls the six branches (1103) to adjust their extension and contraction separately.

6. An active drive calibration method, implemented by using a robot six-dimensional force sensor online calibration device according to any one of claims 1 to 5, characterized in that: The steps include: S0: an online calibration device for a six-dimensional force sensor (111) of a fixedly mounted robot (112); S1: connecting the upper moving platform (1101) and the six-dimensional force sensor (111) of the robot (112) in series; S2: Initializing the six-degree-of-freedom platform (110) and the control system, setting the initial position of the upper moving platform (1101), the initial zero points of the six one-dimensional force sensors (114), and the initial zero point of the six-dimensional force sensor (111); S3: Set the calibration point data required, which is the force or torque in a certain direction, or the synthetic force / torque vector; S4: The control system generates a set of force and displacement adjustment values ​​according to a preset force control algorithm, and sends the length adjustment values ​​to the branch chain (1103); S5: the branch chain (1103) controls the length change of the six branch chains (1103) according to the received length adjustment amount, and drives the upper moving platform (1101) to move; S6: six unidimensional force sensors (114) measure the force exerted on the upper moving platform (1101) in real time, and send the measured force data to the control system; S7: The control system solves the forces and moments of the six degrees of freedom according to the spatial position of the platform, and calculates the forces that need to be further loaded according to the preset calibration points.

7. The active drive calibration method according to claim 6, characterized in that: The control system determines whether the loaded force value satisfies the preset calibration point convergence condition. If so, the calibration process is terminated; if not, the control system returns to step S4.

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