Robotic system, assembly, segment

Abstract

The application relates to a robot system, an assembly, a segment, the segment being configured to perform a rotating motion around a joint, having a processing module, an electronic skin, an angle sensor, a torque sensor and a bearing member; the electronic skin is arranged with a pressure sensor for sensing surface stress and an action point, the electronic skin wraps the surface of the bearing member to form a stress assembly, the torque sensor is located at the joint part of the segment, the stress assembly is physically connected to the detection connection end of the torque sensor to build a mechanical coupling, and the angle sensor is used for measuring the rotating angle of the joint; the processing module resolves a first type of torque generated by the self weight of the segment on the detection connection end according to the angle, calculates a second type of torque generated by external force on the detection connection end according to the stress and the action point, compares and verifies the detection parameters of the torque sensor based on the joint action of the first type of torque and the second type of torque, and executes the calibration of the torque sensor by taking the calculated value of the torque as a reference standard when there is an error.

Description

Technical Field

[0001] This invention relates to the calibration of torque measurement, and more particularly to a robot system, component, or segment. Background Technology

[0002] Six-dimensional force sensors simultaneously measure force in three directions (XYZ three-dimensional force) and torque in three directions (XYZ three-dimensional torque). Based on their working principle and sensing technology, they are classified into capacitive, strain gauge, photoelectric, piezoelectric, electromagnetic, and composite types, among others. Regardless of the type, six-dimensional force sensors require regular calibration to ensure measurement accuracy and reliability. This is because long-term stress on the structure may lead to minor deformation or creep, environmental temperature changes may cause material property drift, and impacts, vibrations, or overloads may alter sensor characteristics.

[0003] In typical industrial applications, such as collaborative robots or production lines, calibration is required every 6 months to 1 year. For high-precision or harsh environments, such as aerospace or surgical robots, calibration may be required every 3 months or even less. As a high-precision measuring instrument, the six-dimensional force sensor is cumbersome to calibrate each time, and most users lack the professional knowledge to perform the calibration themselves. Currently, the common practice is to send it back to the manufacturer or a third-party laboratory for comprehensive calibration, or for the manufacturer to provide professional personnel to unload all external forces on-site and simplify calibration using a calibration kit.

[0004] Currently, the calibration of six-dimensional force sensors all require disassembly for calibration (referred to as offline calibration), which is cumbersome and makes it impossible to achieve dynamic self-calibration during use (referred to as online calibration). Summary of the Invention

[0005] The current consensus on robot systems is that they must have surface tactile capabilities. Robot systems themselves already have three-dimensional force perception capabilities through surface tactile perception. Sensors in robot applications do not necessarily require six-dimensional perception like industrial robotic arms. Sensors can detect torque alone, which, together with the robot's surface tactile perception, forms a system of force and torque sensing. Based on this, this invention proposes an online self-calibration method and device for robot systems.

[0006] This invention provides a segment of a robot system, configured to perform rotational motion around joints adjacent to the segment's joints. The segment includes a processing module, electronic skin, angle sensors, torque sensors, and a support structure for supporting the electronic skin. The electronic skin is equipped with at least one pressure sensor for sensing surface forces and the point of application. The electronic skin wraps around the surface of the support structure to form a force-bearing component. The torque sensor is located at the joint of the segment, and the force-bearing component is physically connected to the detection connection end of the torque sensor, thus establishing a mechanical coupling between them. The angle sensor measures the rotation angle of the joint. The processing module couples the pressure sensor, angle sensor, and torque sensor respectively. Based on the angle, it analyzes the first type of torque generated by the segment's self-weight on the detection connection end; based on the forces and the point of application, it calculates the second type of torque generated by external forces on the detection connection end; based on the combined effect of the first and second types of torques, it compares and verifies the torque sensor's detection parameters; and when errors exist, it uses the calculated torque value as a reference standard to calibrate the torque sensor.

[0007] The segment provided by this invention also includes the following auxiliary solutions:

[0008] The process involves comparing and verifying the torque sensor's detection parameters based on the combined effect of the first and second types of torques. When errors exist, the calculated torque value is used as the reference standard to calibrate the torque sensor. This process further includes: analyzing the first type of torque before applying the external force; applying the external force while ensuring the joint's rotation angle remains unchanged, and calculating the difference between the torque sensor's detection value and the first type of torque; comparing the calculated result of the second type of torque with the difference, and when errors exist, using the calculated result of the second type of torque as the reference standard to calibrate the torque sensor.

[0009] The process of analyzing the first type of torque before the external force is applied further includes: controlling the rotation of the joint so that the segment is in or deviates from the vertical state, and using the current detection value of the torque sensor as the first type of torque.

[0010] The robot system has at least one actuator for performing segmental movement; the segment is equipped with at least one protrusion for calibration by pressing a pressure sensor, the protrusion is fixed in a preset position, and the protrusion serves as a fixed reference for the force application.

[0011] The robot system must have at least a vision device for acquiring images of the outside world.

[0012] The protrusion is equipped with a detection element for sensing the pressing force and an interactive device. The interactive device is configured to feed back the pressing force detected by the detection element to the processing module. The processing module compares and verifies the pressure sensor detection parameters based on the pressing force at least once. If there is an error, the pressing force is used as a reference standard to perform the calibration of the pressure sensor.

[0013] The robot system has at least two mobile robotic arms, with segments being components on the robotic arms; and a processing module that controls one robotic arm to press a segment of the other robotic arm as a pressure sensor to apply external force.

[0014] The torque can be either a single-dimensional torque or a multi-dimensional torque, with the configuration segments calibrating each direction in stages, each time calibrating only the torque in the specified single-dimensional direction.

[0015] The direction of the applied external force is configured to be perpendicular to the rotation center axis of the torque sensor corresponding to the current detection direction.

[0016] Specifically, when both the first type of torque and the second type of torque are zero, the current detection parameters of the torque sensor are used as the new zero-point reference for the torque sensor; when at least one of the first type of torque and the second type of torque is not zero, the self-calibration operation of the torque sensor is performed until the deviation between the reference standard and the detection parameters is reduced to the threshold range.

[0017] Among them, the condition for determining that the first type of torque is zero is that the load-bearing component rotates to an upright state; and / or the condition for determining that the second type of torque is zero is that the electronic skin does not detect surface force.

[0018] In this system, the pressure sensor is located at a specific position on the segment and serves as a reference element for self-calibration; or, the electronic skin has multiple pressure sensors forming a sensing array, which serves as a detection element for detecting force at any position on the skin and a reference element for self-calibration.

[0019] Among them, the phalanges of the mechanical fingers of the robot system are regarded as the first type of segment, and the remaining segments of the robot system that rotate around the joints are regarded as the second type of segment. The torque sensor of the first type of segment is a single type of sensor that only has the function of torque detection.

[0020] The first type of torque sensor includes a base, a detection component, and a capacitance-to-digital conversion circuit. The detection component includes at least a fixed block forming the sensor's detection connection end and a support column extending normally from the bottom of the fixed block. The fixed block is used to physically connect to an external force-bearing component, thereby establishing a mechanical coupling between them. The top of the support column is connected to the fixed block, and the bottom is fixed to the base. The support column acts as a first limiting element to prevent normal compression deformation of the fixed block. At least two transformation units are arranged between the base and the fixed block. Each transformation unit is arranged symmetrically or axially around the support column. The projected area of ​​the transformation unit relative to the base is smaller than the projected area of ​​the fixed block relative to the base, and there is mechanical coupling between the transformation unit and the fixed block. The surface of the base has a moving electrode, and at least one stationary electrode is disposed below each moving electrode on the base. The projection of the moving electrode relative to the stationary electrode covers at least a portion of the area of ​​the corresponding stationary electrode. The moving electrode is insulated from the stationary electrode. The surface accuracy of the stationary electrode is greater than the surface accuracy of the non-stationary electrode area on the surface of the fixed block and / or the surface of the base. The difference in surface accuracy between the moving electrode and the stationary electrode is less than a set threshold. When the fixed block is subjected to force, the conversion unit generates at most a micrometer-level spacing change between the moving electrode and the stationary electrode. A capacitance-to-digital conversion circuit is coupled to the corresponding electrode to obtain the capacitance between the moving electrode and the stationary electrode. A processing module is coupled to the capacitance-to-digital conversion circuit to output an electrical signal characterizing the torque based on the difference between the capacitances.

[0021] The transformation unit is fixed to the base and / or the fixed block, and includes at least one bent electrode formed by an elastic conductor. The bent electrode serves as a moving electrode and generates a preload on the corresponding stationary electrode through bending. The fixed block is forced to drive the transformation unit to change the distance and indirect contact area between the moving electrode and the stationary electrode. The bent electrode and the corresponding stationary electrode in the transformation unit form a symmetrical structure along the geometric center line of the projected area of ​​the stationary electrode relative to the moving electrode along the length direction of the stationary electrode.

[0022] Among them, the segment is the front or middle segment of the mechanical finger; a first transformation unit and a second transformation unit are set between the base and the fixed block, the bending direction of the end or middle segment is taken as the X direction, and the first and second transformation units are distributed along the X-axis.

[0023] Among them, the segment is the terminal phalanx of the mechanical finger; a first transformation unit, a second transformation unit, a third transformation unit, and a fourth transformation unit are set between the base and the fixed block. The first transformation unit and the third transformation unit are distributed along the X-axis, and the second transformation unit and the fourth transformation unit are distributed along the Y-axis.

[0024] Each conversion unit has a first static electrode and a second static electrode below it, and the first static electrode and the second static electrode are symmetrical along the geometric center line.

[0025] Among them, the torque sensor of the second type of segment is a composite sensor that detects both force and torque, or a single sensor that only has the function of torque detection.

[0026] A component of a robot system is also provided, including a processing module and at least two segments. The joints of two adjacent segments are hinged to each other to form a rotary joint. Each segment is provided with an angle sensor and a load-bearing component. The angle sensor is used to measure the rotation angle of the corresponding joint. The load-bearing components of two adjacent segments are mechanically coupled. At least one segment at the front end of the component has an electronic skin. The electronic skin is equipped with at least one pressure sensor for sensing surface force and point of application. The electronic skin wraps around the surface of the corresponding load-bearing component to form a force-bearing component. At least one segment in the component has a torque sensor. The detection connection end of the torque sensor is physically connected to the load-bearing component of the corresponding segment. The processing module couples the pressure sensor, angle sensor, and torque sensor of each segment respectively. Based on the rotation angle of each segment, it analyzes the first type of torque generated by the self-weight of the corresponding load-bearing component on the detection connection end. Based on the force, point of application, and rotation angle of the associated segment, it calculates the second type of torque generated by the external force on the detection connection end. Based on the combined effect of the first type of torque and the second type of torque, it compares and verifies the detection parameters of the torque sensor. When there is an error, the calculated value of the torque is used as a reference standard to perform torque sensor calibration.

[0027] The component further includes: calculating the lever arm from the point of force application to the detection connection end based on the segment rotation angle between the segment where the force application point is located and the end segment of the component, and using the product of the force and the lever arm as the second type of torque.

[0028] A robotic system comprising the aforementioned segments is also provided.

[0029] This invention separates the surface tactile sensing and torque detection systems within a robot system, forming two distinct systems within a segment. Comparative analysis of these two systems allows the torque sensor to differentiate between internal errors and external forces in its detection results. This enables the sensor to calibrate its own system based on the external system's results, achieving online calibration. The robot system can then perform autonomous online calibration, eliminating the need for periodic disassembly and factory recalibration, thus overcoming the challenges of torque sensor calibration. Attached Figure Description

[0030] Figure 1 A schematic diagram of the segments of the robot system of the present invention is given.

[0031] Figure 2 A flowchart based on surface tactile calibration torque sensing detection data is provided.

[0032] Figure 3 A flowchart based on subtraction calibration torque sensor detection data is provided.

[0033] Figure 4aA schematic diagram is given showing that the external force originates from a fixed reference. Figure 4b A diagram illustrating the coordinated application of external force by the robot's two arms is provided.

[0034] Figure 5a This invention provides a first-person perspective of the sensor structure for purely measuring torque according to the present invention. Figure 5a A second perspective of the torque sensor structure.

[0035] Figure 6a A schematic diagram of a robot system composed of multiple segments is given. Figure 6b A diagram illustrating the trigonometric cosine theorem is provided. Detailed Implementation

[0036] The technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention.

[0037] In this invention, a segment of a robot system refers to a basic unit in the robot's mechanical structure that can move independently or bear functions, similar to the joint segments of a living organism (such as the knuckles of a human finger, the humerus and ulna of the arm). It can include knuckles (for dexterous manipulation) or joint modules from other parts of the robot (such as segments of the arm, leg, or torso).

[0038] Example 1

[0039] Figure 1 A schematic diagram of a segment of the robot system of the present invention is provided. The segment is configured to perform rotational movements around joints adjacent to the segment joints on the robot system. Taking a knuckle as an example, the segment includes a processing module, an angle sensor 10, a torque sensor 20, electronic skin 30, and a support member 40 for supporting the electronic skin 30. The support member 40 supports and shapes the knuckle into a biomimetic shape, such as a shell or other support member in the knuckle. The electronic skin 30 serves as a surface tactile sensing component, with at least one pressure sensor disposed thereon for sensing surface forces and the point of application. When the torque sensor to be calibrated is a single-dimensional torque, only one pressure sensor can be provided, corresponding to the dimensional direction; when the torque sensor to be calibrated is a three-dimensional torque, three pressure sensors can be provided, detecting forces in the XYZ three-dimensional directions respectively. When the pressure sensors exist in a small number (not in an array), the pressure sensors are located at specific positions on the segment as reference elements for self-calibration, such as at the fingertip or fingertip of the knuckle. Pressure sensors can also be constructed into sensor arrays that cover the entire or most of the electronic skin area. The sensor array serves as a detection element for detecting force at any location on the skin and a reference element for self-calibration.

[0040] See Figure 1The electronic skin 30 wraps around the surface of the load-bearing component 40 to form a force-bearing component, which receives the applied external force. The robot system needs to sense the torque effect of the force on the joint, and the torque sensor 20 is installed at the joint of the segment. The torque sensor can be one or more combinations of capacitive, strain gauge, photoelectric, piezoelectric, and electromagnetic types, which are not limited in this example. The force-bearing component is physically connected to the detection connection end of the torque sensor 20, establishing a mechanical coupling between the two. When an external force acts on the force-bearing component, it is transmitted to the torque sensor 20 through the mechanical coupling path, causing the sensor to twist and deform. The processing module obtains the detection data from the torque sensor 20. The angle sensor 10 is used to measure the rotation angle of the joint. Its structure and installation can refer to existing settings. Numerous documents, such as CN116945212A, disclose the technology of measuring joint rotation using angle sensors, which will not be elaborated here.

[0041] Figure 2 A flowchart based on surface tactile calibration torque sensing detection data is provided. The processing module couples the pressure sensor, angle sensor 10, and torque sensor 20 to acquire sensing data and executes operation steps S100 to S300.

[0042] S100, the first type of torque generated at the detection connection end based on the self-weight of the segment analyzed by the angle.

[0043] After the mechanical joints of the robot system are manufactured and assembled, their overall mass is fixed, and their gravity is constant. When the joint is in a vertical position, the included angle detected by the angle sensor is θ = 0°. Its own weight does not cause the segment to rotate around the joint, and the torque is zero. In a non-vertical position, the self-weight acts on the segment, generating a rotational driving force. At this time, the first type of torque can be analytically obtained based on the angle. The first type of torque can be obtained through calculation, such as calculating the lever arm based on the known joint length and included angle, and obtaining the torque by multiplying the lever arm by the force. Alternatively, it can be obtained based on the detection value of the torque sensor under conditions where no external force is applied and only the self-weight is affected. It should be understood that the first type of torque refers to the effect of the self-weight on the rotation of the segment around the joint. The first type of torque can be a one-dimensional torque or a three-dimensional torque.

[0044] S200. Calculate the second type of torque generated by the external force on the detection connection end based on the force and the point of application.

[0045] As can be seen from the above, the point of force application can be a specific location where the pressure sensor is located, or any location where the press is detected by the sensor array. Once the point of application is determined, the lever arm is also determined. The second type of torque can be obtained by detecting the magnitude of the external force based on the pressure sensor. The second type of torque refers to the effect of the external force on the rotation of the segment around the joint. It can also be one-dimensional or three-dimensional. The second type of torque is the calculation result based on the pressure sensor.

[0046] S300: The torque sensor detection parameters are compared and verified based on the combined effect of the first type of torque and the second type of torque. When errors exist, the calculated value of the torque is used as the reference standard to perform torque sensor calibration.

[0047] The combined effect of Type I and Type II torques influences the torque acting on the joint. When the sensor is accurate, the combined result is comparable to the torque sensor's detection result. However, the combined effect of Type I and Type II torques is obtained through an external system of the torque sensor, not from the torque sensor's own system. The two can be compared and verified; in case of mismatch, the former can be used as a reference to correct the torque sensor. Numerous existing documents describe sensor calibration methods, such as adjusting the sensor's input-output relationship, which will not be elaborated upon in this paper.

[0048] This invention separates the surface tactile sensing and torque detection systems within a robot system, forming two distinct systems within a segment. Comparative analysis of these two systems allows the torque sensor to differentiate between internal errors and external forces in its detection results. This enables the sensor to calibrate its own system based on the external system's results, achieving online calibration. The robot system can then perform autonomous online calibration, eliminating the need for periodic disassembly and factory recalibration, thus overcoming the challenges of torque sensor calibration.

[0049] As an improvement, refer to Figure 3 Step S300 compares and verifies the torque sensor detection parameters based on the combined effect of the first type of torque and the second type of torque. If an error exists, the calculated torque value is used as the reference standard to perform torque sensor calibration. This further includes:

[0050] S310, Analyze the first type of torque before the external force is applied.

[0051] S310. Apply an external force while ensuring that the rotation angle of the joint remains unchanged, and calculate the difference between the torque sensor detection value and the first type of torque.

[0052] S310. Compare the calculated result of the second type of torque with the difference value to determine the difference. If there is an error between the two, use the calculated result of the second type of torque as the reference standard to perform the calibration of the torque sensor.

[0053] External force is applied via electronic skin sensing. Before the application of external force, the torque is affected by the segment's own weight, and the first type of torque can be obtained through calculation or detection. Preferably, the joint is rotated until the segment is in or deviates from a vertical state. The current detection value of the torque sensor is used as the first type of torque. After the external force is applied, the detection value of the torque sensor corresponds to the combined effect of self-weight and external force. By using the difference between the detection value of the torque sensor 20 and the first type of torque, the influence of self-weight is removed, and the interference of the environment on the detection is eliminated by subtraction, resulting in the pure influence of external force. This is then compared and corrected with the calculated result of the second type of torque. On the other hand, the manufacturer's initial calibration only considers the influence of external force on torque and does not include the self-weight of the loading equipment. By directly obtaining the influence of external force through subtraction for comparison and calibration, it conforms to the manufacturer's calibration mode and ultimately obtains a more accurate correction result.

[0054] As an alternative improvement, the external force can originate from a fixed reference point, or it can originate from the coordinated action of the robot's two arms. In the former approach, the reference point is... Figure 4a The robot system has at least one actuator for performing segmental movement. Each segment is equipped with at least one protrusion for calibration by pressing a pressure sensor. The protrusion is fixed in a preset position and serves as a fixed reference for force application. Using an external object placed at a fixed position as a fixed reference, such as a dedicated calibration cone on a wall, allows the robot to move segments to press, resulting in high torque calibration accuracy, suitable for applications requiring high precision. During robot movement guidance, a vision device can be configured to acquire external images. Based on the vision, the pressing trajectory and position are planned, and the calibration is completed through visual-tactile fusion. Furthermore, the protrusion is equipped with a detection element for sensing the pressing force, as well as an interaction device. The interaction device is configured to feed back the pressing force detected by the detection element to the processing module, using signal transmission or visual recognition feedback. The processing module compares and verifies the pressure sensor detection parameters based on the pressing force. If errors exist, the pressing force is used as a reference standard to perform pressure sensor calibration. The surface tactile feedback can be calibrated first using the cone pressure measurement, completing the surface tactile calibration and ensuring the basis for subsequent calibrations.

[0055] Figure 4b This diagram illustrates the coordinated application of external force by the robot's two arms. In the latter approach, the robot system has at least two mobile robotic arms, with segments being components on the arms. The processing module controls one arm to press a pressure sensor on a segment of the other arm, thus applying external force. When the two-arm system applies external force in coordination, one arm presses down on the other, resulting in a large force application point, suitable for applications where high precision is not required.

[0056] In this invention, the torque can be either single-dimensional or multi-dimensional. Due to the difficulty of decoupling and the fact that the decoupling model was developed through numerous experiments, in the case of multi-dimensional torque, the configuration segments are calibrated in stages in each direction. Each calibration only calibrates the torque in a specified single-dimensional direction. By calibrating only one direction at a time, the need for decoupling introduced by mixing multiple directions is avoided, thus improving calibration efficiency. Similarly, the direction of the applied external force is configured to be perpendicular to the rotation center axis of the torque sensor corresponding to the current detection direction, avoiding decoupling.

[0057] In this invention, calibration may include static zero-point correction and dynamic calibration. During zero-point correction, when both the first and second types of torques are zero, the current detection parameters of the torque sensor 20 are used as the new zero-point reference for the torque sensor 20, and initial output values ​​such as zero-point voltage and / or other digital quantities are recorded. During dynamic calibration, when at least one of the first and second types of torques is not zero, a self-calibration operation of the torque sensor 20 is performed until the deviation between the reference standard and the detection parameters is reduced to a threshold range, verifying the sensor's response under rapidly changing torques. Specifically, the condition for the first type of torque to be zero is that the supporting member 40 rotates to an upright position; and / or, the condition for the second type of torque to be zero is that the electronic skin 30 does not detect surface force.

[0058] The mechanical fingers of the robot system are taken as the first type of segment, and the remaining segments of the robot system that rotate around the joint are taken as the second type of segment. The torque sensor 20 of the first type of segment is a single type sensor with only torque detection function, which reduces the size and cost of the sensor. The torque sensor of the second type of segment is a composite sensor that detects both force and torque or a single type sensor with only torque detection function.

[0059] Based on this, and as a further improvement, refer to Figure 5a , 5bThe first-class segment torque sensor 20 includes a base 100 and a detection component 200. The base 100 uses a PCB board directly as the substrate, facilitating sensor miniaturization. The capacitance-to-digital converter (CDC) circuit and processing module are integrated on the PCB board. The detection component 200 includes a fixing block 210 forming the sensor detection connection end and a support column 220 extending normally from the bottom of the fixing block 210. The fixing block 210 and the support column 220 are integrally formed, saving assembly space and reducing sensor size. The detection component 200 is made entirely of a high-hardness rigid material such as metal or composite material, reducing the impact of beam deformation on measurement and ensuring sufficient rigidity of the support column 220. The top of the support column 220 is connected to the fixing block 210, and the bottom is fixed to the base 100, forming a normal extension (Z-direction as shown in the diagram), serving as a first limiting element to prevent normal compression deformation of the fixing block 210. The fixing block 210 is used to physically connect to the force-bearing component, thereby establishing a mechanical coupling between the two. The fixing block 210 is located on the non-force-bearing surface of the force-bearing component's housing component and is not directly subjected to force. External forces on the force-bearing component are transmitted to the fixing block 210 through the coupling path, allowing for torsional deformation in the X, Y, and / or Z directions. The Z-direction compression is counteracted by the support column 220. Since the fixing block 210 directly serves as the housing component on the non-force-bearing surface, there is no need for connecting rods or other connection structures above it to increase sensor size, saving on connection structures and assembly components between the connection structures and the fixing block 210. The sidewall of the fixing block 210 has mounting holes 211 for locking to the force-bearing component. It is radially mounted to the load-bearing member using miniature screws, further reducing the design of connection structures and assembly components required for the fixing block's force coupling and minimizing sensor size.

[0060] At least two transformation units 400 are provided between the base 100 and the fixing block 210, and each transformation unit 400 is arranged symmetrically or axially around the support column 220. Figure 5a , 5b A three-dimensional torque structure is illustrated, including four transformation units arranged along the X and Y axes and two stationary electrodes 500 at the bottom of each unit. In cases where it is not necessary to measure all three-dimensional torques, the torque sensor structure can be modified or reduced, such as forming a one-dimensional X-axis torque sensor with only two transformation units 400 distributed along the X-axis with the support column 220 as the center of symmetry, and each transformation unit 400 having one stationary electrode 500 at its bottom. The above description of the preferred axially symmetrical distribution of transformation units around the support column describes the design style of a one-dimensional, two-dimensional, or three-dimensional torque sensor. In some alternative embodiments, the transformation units of the torque sensor can form a point-symmetrical distribution structure around the support column. For example, the torque sensor may include three transformation units 400, each uniformly distributed around the support column in a point-symmetrical manner, with one or two stationary electrodes 500 at the bottom of each transformation unit 400, thus constructing a two-dimensional or three-dimensional torque sensor.

[0061] See Figure 5a The conversion unit 400 has a moving electrode on the surface of the base 100. At least one stationary electrode 500 is disposed below each moving electrode on the base 100, and the projection of the moving electrode relative to the stationary electrode 500 at least covers a portion of the area of ​​the corresponding stationary electrode 500. The moving electrode is insulated from the stationary electrode 500. Figure 5aIn this circuit, the conversion unit 400 and the fixed block 210 are mechanically coupled. This coupling can be achieved through connection or pressing. The twisting of the fixed block 210, through this mechanical coupling, causes the moving electrode to undergo at least a change in spacing relative to the stationary electrode 500. Given the sensor size design and the rigid deformation of the detection component 200, this spacing change is on the micrometer scale. Therefore, the projected area of ​​the conversion unit 400 relative to the base 100 is set smaller than the projected area of ​​the fixed block 210 relative to the base 100. The surface precision of the stationary electrode 500 is greater than the surface precision of the areas on the surface of the fixed block 210 and / or the base 100 where the stationary electrode 500 is located. The difference in surface precision between the moving electrode and the stationary electrode 500 is less than a set threshold, resulting in equal or similar precision. In the circuit, a capacitance-to-digital conversion circuit is coupled to the corresponding electrode to obtain the capacitance between the moving electrode and the stationary electrode 500. A processing module is coupled to the capacitance-to-digital conversion circuit to output an electrical signal characterizing the torque based on the difference in capacitance. In one of the optional methods, one of the moving electrode and the stationary electrode 500 can be connected to the excitation end of the CDC and the other to the input end to obtain the mutual capacitance between the moving electrode and the stationary electrode 500; in another optional method, the moving electrode is grounded, and the excitation end and the input end of the CDC are both connected to the stationary electrode 500 to obtain the self-capacitance of the stationary electrode 500 to ground. The above torque sensor structure has the following advantages: (1) The sensor structure only allows torsional deformation, and the support column design prevents the normal pressing of the fixed block. It abandons the measurement of force and only measures torque. Compared with the traditional six-dimensional force sensor, the structural complexity is reduced by a factor of two. The sensor is compact and easy to process, and can be made smaller than the current sensor. If further combined with the PCB base embedding, high-hardness integrated detection component, fixed block connection assembly design, etc., the sensor size can be made as small as 5X5mm, which can fully take into account the joint torque measurement and power routing of small space robot segments. (2) With the help of the sensor structure, the force is physically decoupled. The algorithm only needs to decouple the relationship between multi-dimensional torques, and the decoupling difficulty is reduced by a factor of two. (3) Due to the limitations of the sensor's structural size, the amount of torsional change is at the micrometer level. The reduction in capacitance amplitude caused by the small deformation is compensated by the high precision machining of the surfaces of the moving and stationary electrodes, which are higher than other parts, ensuring that the sensor maintains high sensitivity. Only the moving and stationary electrodes are locally precision machined, and the machining area is smaller than that of traditional parallel plate six-dimensional force sensors. In addition, the sensor structure is simplified and does not require complex decoupling, resulting in a significant reduction in sensor cost and significant economic benefits for multiple torque detection applications. (4) The transformation unit is symmetrically arranged around the support column. The measurement of the transformation unit on the left and right sides of the support column is based on differential to remove common-mode interference such as environmental temperature and humidity, thereby improving measurement sensitivity and anti-interference performance.

[0062] Furthermore, the transformation unit 400 includes at least one bent electrode formed via an elastic conductor. The transformation unit 400 can be formed from a single metal strip or by combining multiple metal strips; the transformation unit 400 as a whole can be composed of a bent electrode, or it can have a structure with a bent lower part and an unbent upper part. To simplify the structure and processing, the transformation unit 400 is preferably made by rolling a single metal strip, with the whole serving as a bent electrode. The bent electrode is fixed to the base 100 and / or the fixing block 210. The bent electrode serves as the aforementioned moving electrode, and by bending, it generates a preload on the corresponding stationary electrode 500. The fixing block 210, under force, causes the transformation unit 400 to change the distance and indirect contact area between the moving electrode and the stationary electrode 500; the bent electrode in the transformation unit 400 and the corresponding stationary electrode 500 form a symmetrical structure along the geometric center line of the projected area of ​​the stationary electrode 500 relative to the moving electrode along the length direction of the stationary electrode 500. The further advantages of this improved sensor structure are: (1) The moving electrode is a curved electrode, which only requires high precision on the surface of the part that can indirectly contact the stationary electrode 500 within the range of the moving electrode, and the area is small; (2) By forming pre-pressure, the processing accuracy requirements are reduced; (3) The capacitance change is greatly increased by the change of contact area; (4) The curved electrode and the stationary electrode are symmetrical about their own center, and the fixed block twists and deforms. The left and right sides inside the unit change at the same time, the deformation amount doubles, and the sensitivity increases.

[0063] In this improved scheme, when the segment is the tip or middle segment of a mechanical finger, a single-dimensional torque measurement is configured for the segment. A first transformation unit and a second transformation unit are set between the base 100 and the fixing block 210. The bending direction of the tip or middle segment is taken as the X-axis, and the first and second transformation units are distributed along the X-axis. During measurement, the fixing block 210 twists along the X-axis. One of the first and second transformation units symmetrically arranged along the support column 220 is pressed down, while the other is pulled up. The indirect contact area between the moving and stationary electrodes on both sides is different. This change can reflect the twisting situation. The processing module outputs an electrical signal representing the X-axis torque based on the difference in capacitance corresponding to the first and second transformation units.

[0064] When the segment is the distal phalanx of a mechanical finger, the segment is configured for three-dimensional torque measurement. A first transformation unit, a second transformation unit, a third transformation unit, and a fourth transformation unit are set between the base 100 and the fixing block 210. The first and third transformation units are distributed along the X-axis, and the second and fourth transformation units are distributed along the Y-axis. Based on this principle, the processing module outputs an electrical signal representing the X-axis torque based on the difference in capacitance between the first and third transformation units, and an electrical signal representing the Y-axis torque based on the difference in capacitance between the second and fourth transformation units. Based on this, it can be understood that when two or four transformation units are axially symmetrical, the difference between the two measurement results in the X-axis direction and / or the two measurement results in the Y-axis direction is considered. Correspondingly, for axially symmetrical cases, such as with three transformation units, the force on each transformation unit can be obtained through trigonometric function decomposition to obtain the results in the two directions of the X-axis or the two directions of the Y-axis. Then, the X-axis result is compared with the X-axis result, and the Y-axis result is compared with the Y-axis result, forming a difference analysis.

[0065] Furthermore, a first static electrode and a second static electrode are disposed below each conversion unit, and the first static electrode and the second static electrode are symmetrical along the aforementioned geometric center line. The moving electrode is a symmetrical ring that twists along the Z-axis. That is, when it twists circumferentially, the area of ​​the moving electrode indirectly contacting the first static electrode and the second static electrode will differ. This difference reflects the circumferential twisting situation. The processing module outputs an electrical signal characterizing the Z-axis torque based on the difference in capacitance between the first static electrode and the second static electrode.

[0066] Example 2

[0067] Figure 6a A schematic diagram of a multi-segment robot system is provided. The component includes a processing module and at least two segments, with the joints of adjacent segments hinged together to form a rotary joint. Each segment is equipped with an angle sensor 10 and a load-bearing member 40. The angle sensor 10 is used to measure the rotation angle of the corresponding joint; the load-bearing members 40 of adjacent segments are mechanically coupled.

[0068] At least one segment at the front end of the component has an electronic skin 30, and the electronic skin 30 is equipped with at least one pressure sensor for sensing surface force and point of application. The electronic skin 30 wraps around the surface of the corresponding load-bearing member 40 to form a load-bearing component. At least one segment in the component has a torque sensor 20, and the detection connection end of the torque sensor 20 is physically connected to the load-bearing member 40 of the corresponding segment.

[0069] The processing module couples pressure sensors, angle sensors 10, and torque sensors 20 to each segment. Based on the rotation angle of each segment, it analyzes the first type of torque generated by the self-weight of the corresponding bearing component 40 on the detection connection end. Based on the force, the point of application, and the rotation angle of the associated segment, it calculates the second type of torque generated by the external force on the detection connection end. Based on the combined effect of the first and second types of torques, it compares and verifies the detection parameters of the torque sensor 20. If errors exist, the calculated torque value is used as the reference standard to calibrate the torque sensor 20. The component further includes: calculating the lever arm from the point of application of the force to the detection connection end based on the segment rotation angle between the segment where the force application point is located and the end segment of the component; the product of the force and the lever arm is used as the second type of torque.

[0070] See Figure 6a , 6b The length of the lever arm of each segment is calculated according to the law of cosines. In any triangle, c

[0071] =a 2 +b 2 -2abcosC, taking L2 as an example, since L1, θ1, and M1 are known, the direction and magnitude of F can be obtained.

[0072] The opposite angle of L2 is θ2' = θ2 - θ1, where θ2 and θ1 are both measured by the angle sensor;

[0073] Substituting into the formula, L2=√(L12+L22-2L1L2cosθ2');

[0074] Similarly, L3, L4, ..., Ln can all be obtained, and then the theoretical torque of each joint can be calculated, which can be calibrated by comparing with the measured values ​​of each set of torque sensors.

[0075] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and are not intended to limit the scope of protection of the present invention. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of the present invention without departing from the essence and scope of the technical solutions of the present invention.

Claims

1. A segment of a robot system, said segment being configured to perform rotational motion about a joint adjacent to the segment joint in the robot system, characterized in that: The segment includes a processing module, electronic skin, angle sensors, torque sensors, and load-bearing components for supporting the electronic skin; The electronic skin is equipped with at least one pressure sensor for sensing surface forces and points of application. The electronic skin wraps around the surface of the load-bearing member to form a force-bearing component. The torque sensor is located at the joint of the segment. The force-bearing component is physically connected to the detection connection end of the torque sensor to establish a mechanical coupling between the two. The angle sensor is used to measure the rotation angle of the joint. The processing module is coupled to a pressure sensor, an angle sensor, and a torque sensor respectively. It calculates a first type of torque generated on the detection connection end based on the self-weight of the angle resolution segment, and calculates a second type of torque generated on the detection connection end based on the force and the point of application. It compares and verifies the detection parameters of the torque sensor based on the combined effect of the first and second types of torques. When there is an error, it uses the calculated value of the torque as a reference standard to perform calibration of the torque sensor.

2. The segment of the robot system according to claim 1, characterized in that, The method of comparing and verifying the torque sensor detection parameters based on the combined effect of the first and second types of torque, and using the calculated torque value as a reference standard to calibrate the torque sensor when errors exist, further includes: Analyze the first-kind torque before the external force is applied; While ensuring that the rotation angle of the joint remains unchanged, an external force is applied, and the difference between the value detected by the torque sensor and the first type of torque is calculated. The difference between the calculated result of the second type of torque and the difference is compared. If there is an error between the two, the calculated result of the second type of torque is used as the reference standard to perform the calibration of the torque sensor.

3. The segment of the robot system according to claim 2, characterized in that, The method of analyzing the first type of torque before the application of external force further includes: The joint is rotated until the segment is in or deviates from a vertical position, and the current detection value of the torque sensor is used as the first type of torque.

4. The segment of the robot system according to claim 1, characterized in that: The robotic system has at least one actuator for performing segmental movement; The segment is equipped with at least one protrusion for calibration by pressing the pressure sensor. The protrusion is fixed in a preset position and serves as a fixed reference for the force application.

5. The segment of the robot system according to claim 4, characterized in that: The robot system has at least a vision device for acquiring images of the outside world.

6. The segment of the robot system according to claim 4, characterized in that: The protrusion is equipped with a detection element for sensing the pressing force, as well as an interactive device; The interactive device is configured to feed back the pressing force detected by the detection element to the processing module. The processing module compares and verifies the pressure sensor detection parameters based on the pressing force at least once. If there is an error, the pressing force is used as a reference standard to perform the calibration of the pressure sensor.

7. The segment of the robot system according to claim 1, characterized in that: The robot system has at least two mobile robotic arms, and the segments are components on the robotic arms; The processing module controls a pressure sensor in which one robotic arm presses a segment of another robotic arm as the application of the external force.

8. A segment of the robot system according to claim 1, characterized in that: The torque is a one-dimensional torque; Alternatively, the torque can be multidimensional, with segments configured to perform calibration in each direction in stages, calibrating only the torque in a specified single-dimensional direction each time.

9. A segment of the robot system according to claim 8, characterized in that: The direction of the applied external force is configured to be perpendicular to the rotation center axis of the torque sensor corresponding to the current detection direction.

10. A segment of the robot system according to claim 1, characterized in that: When both the first and second type of torques are zero, the current detection parameters of the torque sensor are used as the new zero-point reference for the torque sensor. If at least one of the first type of torque and the second type of torque is not zero, the torque sensor performs a self-calibration operation until the deviation between the reference standard and the detection parameter is reduced to the threshold range.

11. A segment of the robot system according to claim 10, characterized in that: The condition for determining that the first type of torque is zero is that the load-bearing component rotates to an upright position; and / or the condition for determining that the second type of torque is zero is that the electronic skin does not detect surface force.

12. A segment of the robot system according to claim 1, characterized in that: The pressure sensor is located at a specific position in the segment and serves as a reference element for self-calibration. Alternatively, the electronic skin may have multiple pressure sensors forming a sensing array, which serves as a detection element for detecting force at any location on the skin and a reference element for self-calibration.

13. A segment of the robot system according to claim 1, characterized in that: The phalanges of the mechanical fingers of the robot system are taken as the first type of segment, and the remaining segments of the robot system that rotate around the joints are taken as the second type of segment. The torque sensor of the first type of segment is a single type of sensor that only has the function of torque detection.

14. A segment of the robot system according to claim 13, characterized in that: The torque sensor of the first type of segment includes a base, a detection component, and a capacitance-to-digital conversion circuit; The detection component includes at least a fixed block constituting the sensor detection connection end and a support column extending from the bottom of the fixed block in the normal direction. The fixed block is used to physically connect to an external force-bearing component to establish a mechanical coupling between the two. The top of the support column is connected to the fixed block, and the bottom is fixed to the base. The support column serves as a first limiting member to prevent the fixed block from deforming in the normal direction. At least two transformation units are provided between the base and the fixed block. Each transformation unit is arranged symmetrically or axially around the support column. The projected area of ​​the transformation unit relative to the base is smaller than the projected area of ​​the fixed block relative to the base. There is mechanical coupling between the transformation unit and the fixed block. The conversion unit has a moving electrode on the surface of the base. At least one stationary electrode is disposed below each moving electrode on the base. The projection of the moving electrode relative to the stationary electrode covers at least a portion of the area of ​​each corresponding stationary electrode. The moving electrode is insulated from the stationary electrode. The surface accuracy of the stationary electrode is greater than the surface accuracy of the area of ​​the fixed block surface and / or the base surface where the non-stationary electrode is located. The difference in surface accuracy between the moving electrode and the stationary electrode is less than a set threshold. When the fixed block is subjected to force, the conversion unit can generate at most a micrometer-level spacing change between the moving electrode and the stationary electrode. A capacitance-to-digital conversion circuit couples the corresponding electrode to obtain the capacitance between the moving electrode and the stationary electrode. The processing module is coupled with a capacitor-to-digital converter circuit, which outputs an electrical signal representing torque based on the difference between capacitors.

15. A segment of the robot system according to claim 14, characterized in that: The conversion unit is fixed to the base and / or the fixed block, including at least one bent electrode formed by an elastic conductor. The bent electrode serves as the moving electrode, and the bending generates a preload on the corresponding stationary electrode. The fixed block is forced to drive the conversion unit to change the distance and indirect contact area between the moving electrode and the stationary electrode. The curved electrode and the corresponding stationary electrode in the transformation unit form a symmetrical structure along the geometric center line of the projected area of ​​the stationary electrode relative to the moving electrode along the length direction of the stationary electrode.

16. A segment of the robot system according to claim 15, characterized in that: The segment is the front or middle segment of the mechanical finger; A first transformation unit and a second transformation unit are provided between the base and the fixed block. The bending direction of the end phalanx or the middle phalanx is taken as the X-direction, and the first transformation unit and the second transformation unit are distributed along the X-axis.

17. A segment of the robot system according to claim 15, characterized in that: The segment is the distal phalanx of the mechanical finger; A first transformation unit, a second transformation unit, a third transformation unit, and a fourth transformation unit are arranged between the base and the fixed block. The first and third transformation units are distributed along the X-axis, and the second and fourth transformation units are distributed along the Y-axis.

18. A segment of the robot system according to claim 15, characterized in that: Below each conversion unit are a first static electrode and a second static electrode, which are symmetrical about the geometric center line.

19. A segment of the robot system according to claim 13, characterized in that: The torque sensor of the second type of segment is a composite sensor that detects both force and torque, or a single sensor that only has torque detection function.

20. A component of a robot system, characterized in that: It includes a processing module and at least two segments, with the joints of two adjacent segments hinged together to form a rotary joint; Each segment is equipped with an angle sensor and a load-bearing component. The angle sensor is used to measure the rotation angle of the corresponding joint. There is mechanical coupling between the load-bearing components of two adjacent segments. At least the segment at the front end of the assembly has an electronic skin. The electronic skin is equipped with at least one pressure sensor for sensing the surface force and the point of application. The electronic skin wraps around the surface of the corresponding load-bearing component to form a force-bearing assembly. At least one segment in the assembly has a torque sensor. The detection connection end of the torque sensor is physically connected to the load-bearing component of the corresponding segment. The processing module is coupled to the pressure sensor, angle sensor and torque sensor of each segment respectively. It analyzes the first type of torque generated by the self-weight of the corresponding bearing component on the detection connection end based on the rotation angle of each segment. It calculates the second type of torque generated by the external force on the detection connection end based on the force, the point of application and the rotation angle of the associated segment. It compares and verifies the detection parameters of the torque sensor based on the combined effect of the first type of torque and the second type of torque. When there is an error, the calculated value of the torque is used as the reference standard to perform the calibration of the torque sensor.

21. The components of the robot system according to claim 20, characterized in that: Based on the segment rotation angle between the segment where the force is applied and the end segment of the component, the lever arm from the force application point to the detection connection end is calculated, and the product of the force and the lever arm is used as the second type of torque.

22. A robot system, characterized in that, Includes the segments as described in any one of claims 1-19.

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