A static deadweight shift type six-dimensional force sensor calibration device and method

Abstract

The application discloses a static heavy displacement type six-dimensional force sensor calibration device and method, belongs to the field of multi-dimensional force sensor calibration, and aims to solve the current six-dimensional force sensor high-precision, high-efficiency and low-cost calibration problem, and has important significance for improving the precision and economy of multi-dimensional force sensor development. Compared with the prior art calibration equipment, the application only contains a static heavy standard device and a two-degree-of-freedom pitching and rolling mechanism, the error transmission chain is short, the loading repeatability and calibration uncertainty are high. The gravity vector constant of the static heavy standard device is projected under each displacement coordinate system of the sensor to realize loading calibration of the calibrated sensor, a multi-element calibration method of the gravity vector constant is established, and an explicit form formula of the calibrated sensor is obtained through multi-element fitting. The structure and calibration mode are very beneficial to automation, the calibration efficiency is high, the development cost is low, and the application is particularly suitable for batch calibration of commercial six-dimensional force sensors, and has considerable application prospect.

Description

Technical Field

[0001] This invention belongs to the field of multidimensional force sensor technology, specifically relating to a six-dimensional force sensor calibration device and method, and more particularly to a low-cost calibration device and method for high-precision and high-efficiency calibration of a static displacement-type six-dimensional force sensor, which is of great significance for improving the accuracy and economy of multidimensional force sensor development. Background Technology

[0002] Six-dimensional force sensors are commonly used in robotics, automotive testing, medical, and aerospace fields to provide accurate force and torque measurement and sensing capabilities. Calibration is a crucial step in the development of six-dimensional force sensors. Unlike single-component force sensors (such as load cells, tension sensors, and torque sensors), six-dimensional force sensors exhibit significant crosstalk between their various measurement components, making the decoupling formula for obtaining a six-dimensional force sensor complex and difficult.

[0003] Existing technologies primarily employ calibration by applying known orthogonal forces and moment loads in a Cartesian coordinate system. Typically, the sensor to be calibrated is mounted on an adjustment system, using stepped weights, electric cylinders with force sensors, etc., as force sources. A loading head is installed on the sensor, and force is transmitted through pulleys and steel belts. The loading point is decoupled using knife edges, hinges, etc. The main problems with this approach are as follows:

[0004] (1) The calibration system is expensive and has a long development cycle. Because it requires a sufficient number of stepped weights or electric cylinder + electric cylinder force source systems, as well as a six-automatic adjustment system, pulley system, loading head and loading point decoupling system such as loading knife edge and hinge, the development cost of calibration equipment ranges from hundreds of thousands to millions of yuan. The design and manufacturing of each subsystem is difficult and the development cycle is long.

[0005] (2) The calibration equipment has high system error and low load repeatability. Due to the large number of components in the calibration system and the many error sources, the components influence each other, resulting in a long error transmission chain and low system calibration uncertainty. In addition, the long error transmission chain and the influence of moving connections such as knife edges make it difficult to guarantee the system load repeatability.

[0006] (3) It is difficult to achieve a high degree of automation and the calibration efficiency is low. Due to the complexity of the calibration system and the complexity of automatic control, it is difficult to achieve a high degree of automation. At the same time, the OFAT (one component at a time) calibration method is mainly used. For the batch calibration of commercial six-dimensional force sensors, this calibration method is very inefficient and cannot meet the market demand.

[0007] In summary, there is an urgent need to find a low-cost calibration device and method suitable for high-precision and high-efficiency calibration of six-dimensional force sensors, so as to meet the urgent needs of robotics, aerospace and other fields for high-quality and low-cost six-dimensional force sensors. Summary of the Invention

[0008] The purpose of this invention is to provide a static displacement type six-dimensional force sensor calibration device and method to solve the problem of additional space occupied by existing large continuous wind tunnel main drive motor stator drying devices. The technical solution adopted by this invention is as follows:

[0009] A static weight displacement type six-dimensional force sensor calibration device includes a pitch mechanism, a roll mechanism, a sensor mounting base, a sensor adapter, and a static weight standard assembly. The pitch mechanism is connected to a foundation via a mounting flange and has an upwardly extending pitch output shaft. The adapter flange is connected to the pitch output shaft. The roll mechanism is mounted on the adapter flange and has a horizontally extending roll output shaft. The fixed end of the sensor to be calibrated is coaxially connected to the roll output shaft via the sensor mounting base. The static weight standard assembly includes a static weight main standard, which is coaxially connected to the force-bearing end of the sensor to be calibrated via the sensor adapter. The sensor to be calibrated is the six-dimensional force sensor.

[0010] Furthermore, a conical countersunk hole is formed along the axis of the static weight main standard, and the cone head of the mounting cone is inserted into the conical countersunk hole. The other end of the mounting cone is coaxially connected to the sensor adapter.

[0011] Furthermore, the taper of the cone head is 1:10, and the taper of the conical countersunk hole is 1:10.

[0012] Furthermore, the static weight standard assembly also includes an additional static weight standard. The main static weight standard is a square prism component with a square cross-section. Several main expansion screw holes are arranged at intervals along the length direction on the four circumferential sides of the main static weight standard. Any one or more main expansion screw holes are connected to a screw at one end of one or more additional static weight standards.

[0013] Furthermore, the other end of the additional static weight standard is provided with a secondary expansion screw hole, and several additional static weight standards are connected in sequence through the screw and the secondary expansion screw hole.

[0014] Furthermore, the pitch mechanism includes a pitch motor and a pitch reducer. The output shaft of the pitch motor is connected to the input shaft of the pitch reducer. The output shaft of the pitch reducer is a pitch output shaft, and a pitch photoelectric encoder is provided on the pitch output shaft. The roll mechanism includes a roll motor and a roll reducer. The output shaft of the roll motor is connected to the input shaft of the roll reducer. The output shaft of the roll reducer is a roll output shaft, and a roll photoelectric encoder is provided on the roll output shaft.

[0015] This invention also provides a calibration method for a static displacement six-dimensional force sensor, which is based on the aforementioned static displacement six-dimensional force sensor calibration device and includes the following steps:

[0016] Step 1: Establish a calibration load table;

[0017] Step 2: Perform load calibration;

[0018] Step 3: Process the calibration data.

[0019] Furthermore, the specific steps of step one are as follows:

[0020] Step 11, Preliminary determination of the displacement sequence:

[0021] The static weight standard component is initially selected based on the range of the sensor being calibrated, and the allowable pitch and roll angle displacement sequence is initially determined according to 120% of the range.

[0022] Step 12, Determine the basic calibration status:

[0023] The x-axis and z-axis of the sensor to be calibrated are both set horizontally, and the y-axis is set upward. The center of gravity of the static weight standard component is located in the zy plane, which serves as the basic state of the sensor to be calibrated.

[0024] Step 13: Transform the gravity vector of the static standard component to the coordinate system of the sensor being calibrated:

[0025] In its basic state, the force vector of the static weight standard component in the coordinate system of the sensor being calibrated is:

[0026] ;

[0027] In the formula:

[0028] G is the gravity acting on the static weight standard component;

[0029] G 0x Let G be the component of gravity G along the x-axis of the sensor being calibrated;

[0030] G 0y Let G be the component of gravity G along the y-axis of the sensor being calibrated;

[0031] G 0z Let G be the component of gravity G along the z-axis of the sensor being calibrated;

[0032] In its basic state, the coordinates of the center of gravity of the static weight standard component in the coordinate system of the sensor being calibrated are:

[0033] ; In the formula: MG is the bending moment vector of the gravity acting on the static standard component relative to the center of the sensor (5) being calibrated; M 0xLet MG be the component of the sensor (5) being calibrated on the x-axis; M 0y Let MG be the component of MG on the y-axis of the sensor (5) being calibrated; M 0z Let MG be the z-axis component of the sensor (5) being calibrated; zG is the distance between the center of gravity of the static standard component and the center of the sensor (5) being calibrated in the z-axis direction;

[0034] The agreement is to adjust the roll angle first. Then adjust the pitch angle. Then, the attitude rotation transformation matrix relative to the i-th displacement sequence of the basic state is:

[0035] ; In the formula: Let be the rotation transformation matrix of the i-th displacement sequence; Let be the elementary rotation transformation matrix about the x-axis in the i-th displacement sequence; Let be the basic element rotation transformation matrix about the z-axis in the i-th displacement sequence; Let be the rotation angle around the x-axis in the i-th displacement sequence; Let be the rotation angle around the z-axis in the i-th displacement sequence;

[0036] The force vector exerted by the static weight standard component on the sensor under calibration in the i-th displacement sequence is:

[0037] ;

[0038] The torque vector exerted by the static weight standard component on the sensor under calibration in the i-th displacement sequence is:

[0039] ; in, The force along the x-axis in the i-th displacement state; The force along the y-axis in the i-th displacement state; The force along the z-axis in the i-th displacement state; Mxi is the torque about the x-axis in the i-th displacement state; Let be the torque about the y-axis in the i-th displacement state; Let be the torque about the z-axis in the i-th displacement state;

[0040] Adjusting the roll angle and pitch angle During the transition process, ensure that the load on the sensor being calibrated does not exceed the sensor's limit load.

[0041] Step 14, Overload Determination:

[0042] Verify whether the force vector and torque vector acting on the sensor under each displacement state exceed 120% of the range. If they do, it is determined to be overloaded, and return to repeat step one. If they do not exceed, it is determined to be not overloaded, and proceed to the next step.

[0043] Step 15: Based on the overload determination results, establish a calibration load table and determine the displacement sequence matrix as follows:

[0044] ;

[0045] In the formula, [P] is the calibration load matrix; M is the total number of transposition sequences; The force along the x-axis in the Mth displacement state; The force along the y-axis in the Mth displacement state; The force along the z-axis in the Mth displacement state; Let be the torque about the x-axis in the Mth displacement state; Let be the torque about the y-axis in the Mth displacement state; Let be the torque about the z-axis in the Mth displacement state.

[0046] Furthermore, the specific steps of step two are as follows:

[0047] Step 21, zeroing in the absence of the aforementioned static weight standard component:

[0048] Disassemble the static weight standard component and finely adjust the roll angle according to a predefined displacement sequence using pitch and roll photoelectric encoders. and pitch angle After positioning, the zero-load output matrix of the sensor being calibrated is collected as follows:

[0049] ; In the formula, [U0] is the zero-load output matrix; The first element zero-load voltage signal is output under the Mth displacement state; The output is the second zero-load voltage signal of the Mth displacement state; The third element zero-load voltage signal is output for the Mth displacement state; The fourth element zero-load voltage signal is output for the Mth displacement state; The fifth element zero-load voltage signal is output under the Mth displacement state; The sixth element zero-load voltage signal is output for the Mth displacement state;

[0050] Step 22, data acquisition with the aforementioned static weight standard component:

[0051] Install the static weight standard assembly, and tighten the cone head of the mounting cone into the conical countersunk hole of the static weight main standard by screwing it in to achieve an interference fit. After tightening, remove the screw.

[0052] The roll angle is finely adjusted based on feedback from the pitch and roll photoelectric encoders according to a predefined displacement sequence. and pitch angle After positioning, the loaded output matrix of the sensor being calibrated is acquired:

[0053] ; In the formula, [U] is the loaded output matrix; The first element load voltage signal output is for the Mth displacement state; The output is the second-order load voltage signal for the Mth displacement state; The third element load voltage signal is output for the Mth displacement state; The fourth element load voltage signal is output for the Mth displacement state; The fifth element load voltage signal is output under the Mth displacement state; This is the output of the sixth element's load voltage signal in the Mth displacement state.

[0054] Furthermore, the specific steps of step three are as follows:

[0055] Step 31, Processing the voltage difference matrix:

[0056] Based on the zero-load output and the loaded output obtained in step two, the voltage difference is calculated using the following formula:

[0057] ;

[0058] Based on the channel coupling relationship given by the sensor under test, channel coupling is performed, and the six-dimensional strain voltage output formulas of the sensor under test are as follows:

[0059] ;

[0060] ;

[0061] ;

[0062] ;

[0063] ;

[0064] ; In the formula, The voltage signal output of the first channel of the sensor being calibrated (5); The voltage signal output of the second channel of the sensor being calibrated (5); The voltage signal output of the third channel of the sensor being calibrated (5); The voltage signal output of the fourth channel of the sensor being calibrated (5); The voltage signal output of the fifth channel of the sensor being calibrated (5); The voltage signal output of the sixth channel of the sensor being calibrated (5); ΔUx is the voltage signal output of the x component after channel coupling; The output is the voltage signal of the y component after channel coupling; The output is the voltage signal of the z-component after channel coupling; The voltage signal output of the Mx component after channel coupling; The output voltage signal of the My component after channel coupling; The output voltage signal of the Mz component after channel coupling;

[0065] The corrected zero-point voltage difference matrix after coupling is:

[0066] ;

[0067] Step 32, calculate the formula for the sensor being calibrated;

[0068] Establish a six-variable first-order explicit linear formula model:

[0069] ;

[0070] in, It is a 6×6 matrix of undetermined coefficients;

[0071] The matrix form is as follows:

[0072] ;

[0073] The load matrix-voltage difference matrix equations are established as follows:

[0074] ;

[0075] The undetermined coefficient matrix is ​​calculated using a multivariate fitting method.

[0076] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0077] 1. This invention proposes for the first time a six-dimensional force sensor calibration method based on standard static displacement, which realizes the loading calibration of the sensor under calibration by projecting the gravity vector constant of the static standard component onto the sensor's displacement coordinate system.

[0078] 2. Compared with existing calibration equipment, the present invention has a shorter error transmission chain, consisting only of a static weight standard and a two-degree-of-freedom pitch and roll mechanism. It eliminates the load transmission links such as pulleys, steel belts, hinges, and loading heads in existing technologies, resulting in high load repeatability and calibration uncertainty.

[0079] 3. This invention revolutionizes the existing calibration method that uses one component at a time, and establishes a multivariate calibration method for the constant gravity vector. The number of calibration points can be expanded infinitely, and the explicit formula of the sensor being calibrated is obtained through multivariate fitting.

[0080] 4. The structure and calibration method described in this invention are highly conducive to automation, have high calibration efficiency, and low development cost. They are particularly suitable for batch calibration of commercial six-dimensional force sensors and have considerable application prospects. Attached Figure Description

[0081] Figure 1 This is an isometric view of the device of the present invention;

[0082] Figure 2 This is a front view of the device of the present invention;

[0083] Figure 3 This is a top view of the device of the present invention;

[0084] Figure 4 This is a schematic diagram of the structure with an additional static weight standard;

[0085] Figure 5 This is a schematic diagram of the pitch displacement of the device of the present invention;

[0086] Figure 6 This is a schematic diagram of the roll displacement of the device of the present invention;

[0087] Figure 7 This is a flowchart of the method of the present invention.

[0088] In the diagram: 1. Main static weight standard; 2. Screw; 3. Mounting cone; 4. Sensor adapter; 5. Sensor to be calibrated; 6. Sensor mounting base; 7. Roll output shaft; 8. Roll photoelectric encoder; 9. Roll mechanism; 10. Adapter flange; 11. Pitch output shaft; 12. Pitch photoelectric encoder; 13. Pitch mechanism; 14. Mounting flange; 15. Additional static weight standard; 16. Main expansion screw hole; 17. Secondary expansion screw hole. Detailed Implementation

[0089] To make the objectives, technical solutions, and advantages of this invention clearer, the invention is described below with reference to specific embodiments shown in the accompanying drawings. However, it should be understood that these descriptions are merely exemplary and not intended to limit the scope of the invention. Furthermore, descriptions of well-known structures and technologies are omitted in the following description to avoid unnecessarily obscuring the concept of the invention.

[0090] The connections mentioned in this invention are divided into fixed connections and detachable connections. Fixed connections, also known as non-detachable connections, include but are not limited to conventional fixed connection methods such as folded connections, riveted connections, adhesive connections, and welded connections. Detachable connections include but are not limited to conventional disassembly methods such as bolted connections, snap-fit ​​connections, pin connections, and hinged connections. When a specific connection method is not explicitly defined, it is assumed that at least one existing connection method can be found to achieve this function, and those skilled in the art can choose according to their needs. For example, a welded connection can be chosen for fixed connections, and a bolted connection can be chosen for detachable connections.

[0091] The present invention will be further described in detail below with reference to the accompanying drawings. The following embodiments are explanations of the present invention, but the present invention is not limited to the following embodiments.

[0092] Example 1: As Figures 1-6As shown, a static weight displacement type six-dimensional force sensor calibration device includes a pitch mechanism 13, a roll mechanism 9, a sensor mounting base 6, a sensor adapter 4, and a static weight standard assembly. The pitch mechanism 13 is connected to the foundation via a mounting flange 14. The pitch mechanism 13 has an upwardly extending pitch output shaft 11, and a transition flange 10 is connected to the pitch output shaft 11. The roll mechanism 9 is mounted on the transition flange 10 and has a horizontally extending roll output shaft 7. The fixed end of the sensor 5 to be calibrated is coaxially connected to the roll output shaft 7 via the sensor mounting base 6. The static weight standard assembly includes a static weight main standard 1, which is coaxially connected to the force-bearing end of the sensor 5 to be calibrated via the sensor adapter 4. The sensor 5 to be calibrated is the six-dimensional force sensor.

[0093] The static weight main standard 1 has a conical countersunk hole along its axis. The cone head of the mounting cone 3 is inserted into the conical countersunk hole, and the other end of the mounting cone 3 is coaxially connected to the sensor adapter 4.

[0094] The taper of the cone head is 1:10, and the taper of the conical countersunk hole is 1:10.

[0095] The static weight standard assembly also includes an additional static weight standard 15. The main static weight standard 1 is a quadrangular prism component with a square cross-section. Several main expansion screw holes 16 are arranged at intervals along the length direction on the four circumferential sides of the main static weight standard 1. Any one or more main expansion screw holes 16 are connected to a screw at one end of one or more additional static weight standards 15 to increase the loaded weight and adjust the center of gravity position.

[0096] The other end of the additional static weight standard 15 is provided with a secondary expansion screw hole 17. Several additional static weight standards 15 are connected in sequence through the screw and the secondary expansion screw hole 17. According to the calibration range, multiple sets of main static weight standards 1 and additional static weight standards 15 can be set. The main static weight standards 1 and additional static weight standards 15 are high-density metal material components that have been measured and have accurate weight information and center of gravity information. The mass error of the main static weight standards 1 and additional static weight standards 15 is 0.0016%FS.

[0097] The pitch mechanism 13 includes a pitch motor and a pitch reducer. The output shaft of the pitch motor is connected to the input shaft of the pitch reducer. The output shaft of the pitch reducer is a pitch output shaft 11. A pitch photoelectric encoder 12 is provided on the pitch output shaft 11 for accurately measuring the phase of the pitch output shaft 11. The pitch output shaft 11 can achieve a 360° pitch angle rotation with an adjustment accuracy of 0.002°. The roll mechanism 9 includes a roll motor and a roll reducer. The output shaft of the roll motor is connected to the input shaft of the roll reducer. The output shaft of the roll reducer is a roll output shaft 7. A roll photoelectric encoder 8 is provided on the roll output shaft 7 for accurately measuring the phase of the roll output shaft 7. Based on the rotation of the pitch output shaft 11, the roll output shaft 7 can achieve a 360° roll angle rotation with an adjustment accuracy of 0.002°.

[0098] Example 2: Figures 1 to 7 As shown, a calibration method for a static displacement six-dimensional force sensor is implemented based on the static displacement six-dimensional force sensor calibration device described in Embodiment 1, and includes the following steps:

[0099] Step 1: Establish a calibration load table;

[0100] Step 2: Perform load calibration;

[0101] Step 3: Process the calibration data.

[0102] The specific steps for step one are as follows:

[0103] Step 11, Preliminary determination of the displacement sequence:

[0104] The static weight standard component is initially selected based on the range of the sensor 5 being calibrated, and the allowable pitch and roll angle displacement sequence is initially determined according to 120% of the range.

[0105] Step 12, Determine the basic calibration status:

[0106] The x-axis and z-axis of the sensor to be calibrated 5 are both set horizontally, and the y-axis is set upward. The center of gravity of the static weight standard component is located in the zy plane, which is the basic state of the sensor to be calibrated 5.

[0107] Step 13: Transform the gravity vector of the static standard component to the coordinate system of the sensor 5 being calibrated:

[0108] In its basic state, the force vector of the static weight standard component in the coordinate system of the sensor 5 being calibrated is:

[0109] ;

[0110] In the formula:

[0111] G is the gravity acting on the static weight standard component;

[0112] G 0x The component of gravity G along the x-axis of the sensor 5 being calibrated;

[0113] G 0y The component of gravity G along the y-axis of the sensor 5 being calibrated;

[0114] G 0z The component of gravity G along the z-axis of the sensor 5 being calibrated;

[0115] In its basic state, the coordinates of the center of gravity of the static weight standard component in the coordinate system of the sensor 5 being calibrated are:

[0116] ; In the formula: MG is the bending moment vector of the gravity acting on the static standard component relative to the center of the sensor (5) being calibrated; M 0x Let MG be the component of the sensor (5) being calibrated on the x-axis; M 0y Let MG be the component of MG on the y-axis of the sensor (5) being calibrated; M 0z Let MG be the z-axis component of the sensor (5) being calibrated; zG is the distance between the center of gravity of the static standard component and the center of the sensor (5) being calibrated in the z-axis direction;

[0117] The agreement is to adjust the roll angle first. Then adjust the pitch angle. Then, the attitude rotation transformation matrix relative to the i-th displacement sequence of the basic state is:

[0118] ; In the formula: Let be the rotation transformation matrix of the i-th displacement sequence; Let be the elementary rotation transformation matrix about the x-axis in the i-th displacement sequence; Let be the basic element rotation transformation matrix about the z-axis in the i-th displacement sequence; Let be the rotation angle around the x-axis in the i-th displacement sequence; Let be the rotation angle around the z-axis in the i-th displacement sequence;

[0119] The force vector exerted by the static weight standard component on the calibrated sensor 5 under the i-th displacement sequence is:

[0120] ;

[0121] The torque vector exerted by the static weight standard component on the calibrated sensor 5 under the i-th displacement sequence is:

[0122] ; in, The force along the x-axis in the i-th displacement state; The force along the y-axis in the i-th displacement state; The force along the z-axis in the i-th displacement state; Mxi is the torque about the x-axis in the i-th displacement state; Let be the torque about the y-axis in the i-th displacement state; Let be the torque about the z-axis in the i-th displacement state;

[0123] Adjusting the roll angle and pitch angle During the transition process, ensure that the load on the sensor being calibrated 5 does not exceed the limit load of the sensor being calibrated 5.

[0124] Step 14, Overload Determination:

[0125] Verify whether the force vector and torque vector acting on the sensor 5 under each displacement state exceed 120% of the range. If they do, it is determined to be overloaded, and return to repeat step one. If they do not exceed, it is determined to be not overloaded, and proceed to the next step.

[0126] Step 15: Based on the overload determination results, establish a calibration load table and determine the displacement sequence matrix as follows:

[0127] ;

[0128] In the formula, [P] is the calibration load matrix; M is the total number of transposition sequences; The force along the x-axis in the Mth displacement state; The force along the y-axis in the Mth displacement state; The force along the z-axis in the Mth displacement state; Let be the torque about the x-axis in the Mth displacement state; Let be the torque about the y-axis in the Mth displacement state; Let be the torque about the z-axis in the Mth displacement state.

[0129] The specific steps for step two are as follows:

[0130] Step 21, zeroing in the absence of the aforementioned static weight standard component:

[0131] Disassemble the static weight standard component, and finely adjust the roll angle according to a predefined displacement sequence via the pitch photoelectric encoder 12 and the roll photoelectric encoder 8. and pitch angle After positioning, the zero-load output matrix of the sensor 5 being calibrated is collected as follows:

[0132] ; In the formula, [U0] is the zero-load output matrix; The first element zero-load voltage signal is output under the Mth displacement state; The output is the second zero-load voltage signal of the Mth displacement state; The third element zero-load voltage signal is output for the Mth displacement state; The fourth element zero-load voltage signal is output for the Mth displacement state; The fifth element zero-load voltage signal is output under the Mth displacement state; The sixth element zero-load voltage signal is output for the Mth displacement state;

[0133] Step 22, data acquisition with the aforementioned static weight standard component:

[0134] Install the static weight standard assembly, and tighten the cone head of the mounting cone 3 into the conical countersunk hole of the static weight main standard 1 by screw 2 to achieve an interference fit. After tightening, remove screw 2.

[0135] The roll angle is finely adjusted based on feedback from the pitch photoelectric encoder 12 and the roll photoelectric encoder 8 according to a predefined displacement sequence. and pitch angle After positioning, the loaded output matrix of the sensor 5 being calibrated is acquired:

[0136] ; In the formula, [U] is the loaded output matrix; The first element load voltage signal output is for the Mth displacement state; The output is the second-order load voltage signal for the Mth displacement state; The third element load voltage signal is output for the Mth displacement state; The fourth element load voltage signal is output for the Mth displacement state; The fifth element load voltage signal is output under the Mth displacement state; This is the output of the sixth element's load voltage signal in the Mth displacement state.

[0137] The specific steps for step three are as follows:

[0138] Step 31, Processing the voltage difference matrix:

[0139] Based on the zero-load output and the loaded output obtained in step two, the voltage difference is calculated using the following formula:

[0140] ;

[0141] Based on the channel coupling relationship given by the sensor under test 5, channel coupling is performed, and the six-dimensional strain voltage output formulas of the sensor under test 5 are as follows:

[0142] ;

[0143] ;

[0144] ;

[0145] ;

[0146] ;

[0147] ; In the formula, The voltage signal output of the first channel of the sensor being calibrated (5); The voltage signal output of the second channel of the sensor being calibrated (5); The voltage signal output of the third channel of the sensor being calibrated (5); The voltage signal output of the fourth channel of the sensor being calibrated (5); The voltage signal output of the fifth channel of the sensor being calibrated (5); The voltage signal output of the sixth channel of the sensor being calibrated (5); ΔUx is the voltage signal output of the x component after channel coupling; The output is the voltage signal of the y component after channel coupling; The output is the voltage signal of the z-component after channel coupling; The voltage signal output of the Mx component after channel coupling; The output voltage signal of the My component after channel coupling; The output voltage signal of the Mz component after channel coupling;

[0148] The corrected zero-point voltage difference matrix after coupling is:

[0149] ;

[0150] Step 32, calculate the formula for the sensor 5 being calibrated;

[0151] Establish a six-variable first-order explicit linear formula model:

[0152] ;

[0153] in, It is a 6×6 matrix of undetermined coefficients;

[0154] The matrix form is as follows:

[0155] ;

[0156] The load matrix-voltage difference matrix equations are established as follows:

[0157] ;

[0158] The undetermined coefficient matrix was calculated using a multivariate fitting method, thus completing the calibration of sensor 5.

[0159] The error of the single-component loading applied under typical displacement conditions during calibration is:

[0160] ;

[0161] After calibration, crosstalk can be reduced to less than 0.3%FS.

[0162] The working principle of this invention is:

[0163] This invention achieves loading calibration of the sensor 5 under calibration by projecting the constant gravity vector of the static standard component onto the various displacement coordinate systems of the sensor 5 under calibration.

[0164] Specifically, the sensor under calibration 5 is mounted on the pitch mechanism 13 and roll mechanism 9, achieving two degrees of freedom of rotation. Following a certain pitch and roll displacement sequence, the zero-load output under conditions without a static weight standard component is collected. Then, the static weight standard component is directly mounted on the sensor under calibration 5, and the loaded output under conditions with the static weight standard component is collected according to the same pitch and roll displacement sequence. The voltage difference matrix between the loaded and zero-load outputs under the pitch and roll displacement sequences is multiplied by the projection of the static weight standard component onto the displacement coordinate systems of the sensor under calibration 5 under the pitch and roll displacement sequences to establish a calibration load matrix. A transcendental equation system is established using the voltage difference matrix and the calibration load matrix, and the explicit formula for the calibrated sensor is obtained through multivariate fitting.

[0165] The beneficial effects of this invention are:

[0166] (1) This invention proposes for the first time a six-dimensional force sensor calibration method based on standard static displacement, which realizes the loading calibration of the sensor under calibration by projecting the gravity vector constant of the static standard component onto the sensor's displacement coordinate system.

[0167] (2) Compared with the existing technology, the error transmission chain of the calibration equipment is short. It only includes a static weight standard and a two-degree-of-freedom pitch and roll mechanism. It eliminates the load transmission links such as pulleys, steel belts, hinges, and loading heads in the existing technology, and has high load repeatability and calibration uncertainty.

[0168] (3) This invention innovates the existing calibration method of one component at a time and establishes a multivariate calibration method for the constant gravity vector. The number of calibration points can be expanded infinitely. The explicit formula of the sensor being calibrated is obtained through multivariate fitting.

[0169] (4) The structure and calibration method described in this invention are very conducive to automation, have high calibration efficiency, and low development cost. They are particularly suitable for batch calibration of commercial six-dimensional force sensors and have considerable application prospects.

[0170] Existing calibration techniques involve loading known loads in a known, fixed coordinate system. However, the loading table of this invention recalculates based on displacement angles. It accurately calculates the component of the static weight standard component's gravity vector in the moving coordinate system based on two precisely fed-back displacement angles, dynamically forming a new loading table. This greatly simplifies the configuration of calibration equipment and is a prerequisite for achieving fully automatic, efficient, and high-precision calibration.

[0171] To address the impact of the initial zero point on calibration, this invention employs a method of successively back-calculating the self-weight of the zero-point state until the self-weight error of the last two iterations stops within the required deviation. At this point, the calibration formula achieves higher accuracy.

[0172] This invention solves the industrial challenge of achieving high traceability and batch automated calibration for sensors / wind tunnel balances. Existing technologies suffer from large system errors, while the solution of this invention has a short error propagation chain, comprising only two components: a static weight standard component and an angle feedback system, resulting in low system error and high calibration accuracy. Furthermore, existing technologies have poor installation processes (requiring multiple loading of weights, and electromechanical, hydraulic, and pneumatic loading requiring multiple connections), impacting the efficiency of batch and automated calibration.

[0173] The above embodiments are merely illustrative examples of the present invention and do not limit its scope of protection. Those skilled in the art can make partial changes to them, as long as they do not exceed the spirit and essence of the present invention, they are all within the scope of protection of the present invention.

Claims

1. A static displacement type six-dimensional force sensor calibration device, characterized in that: The system includes a pitch mechanism (13), a roll mechanism (9), a sensor mounting base (6), a sensor adapter (4), and a static weight standard assembly. The pitch mechanism (13) is connected to the foundation via a mounting flange (14). The pitch mechanism (13) has an upwardly extending pitch output shaft (11). A transition flange (10) is connected to the pitch output shaft (11). The roll mechanism (9) is mounted on the transition flange (10). The roll mechanism (9) has a horizontally extending roll output shaft (7). The fixed end of the sensor to be calibrated (5) is coaxially connected to the roll output shaft (7) via the sensor mounting base (6). The static weight standard assembly includes a static weight main standard (1). The static weight main standard (1) is coaxially connected to the force-bearing end of the sensor to be calibrated (5) via the sensor adapter (4). The sensor to be calibrated (5) is the six-dimensional force sensor. The static weight standard assembly also includes an additional static weight standard (15). The main static weight standard (1) is a quadrangular prism component with a square cross-section. Several main expansion screw holes (16) are arranged at intervals along the length direction on the four circumferential sides of the main static weight standard (1). Any one or more main expansion screw holes (16) are connected to the screw at one end of one or more additional static weight standards (15). The other end of the additional static weight standard (15) is provided with a secondary expansion screw hole (17), and several additional static weight standards (15) are connected in sequence through the screw and the secondary expansion screw hole (17).

2. The static displacement type six-dimensional force sensor calibration device according to claim 1, characterized in that: The static weight main standard (1) has a conical countersunk hole along its axis. The cone head of the mounting cone (3) is inserted into the conical countersunk hole. The other end of the mounting cone (3) is coaxially connected to the sensor adapter (4).

3. The static displacement type six-dimensional force sensor calibration device according to claim 2, characterized in that: The taper of the cone head is 1:10, and the taper of the conical countersunk hole is 1:

10.

4. The static displacement type six-dimensional force sensor calibration device according to claim 2, characterized in that: The pitch mechanism (13) includes a pitch motor and a pitch reducer. The output shaft of the pitch motor is connected to the input shaft of the pitch reducer. The output shaft of the pitch reducer is a pitch output shaft (11). A pitch photoelectric encoder (12) is provided on the pitch output shaft (11). The roll mechanism (9) includes a roll motor and a roll reducer. The output shaft of the roll motor is connected to the input shaft of the roll reducer. The output shaft of the roll reducer is a roll output shaft (7). A roll photoelectric encoder (8) is provided on the roll output shaft (7).

5. A method for calibrating a static displacement six-dimensional force sensor, based on the static displacement six-dimensional force sensor calibration device described in claim 4, characterized in that, Includes the following steps: Step 1: Establish a calibration load table; Step 2: Perform load calibration; Step 3: Process calibration data; The specific steps of step one are as follows: Step 11, Preliminary determination of the displacement sequence: The static weight standard component is initially selected based on the range of the sensor (5) being calibrated, and the allowable pitch and roll angle displacement sequence is initially determined according to 120% of the range. Step 12, Determine the basic calibration status: The x-axis and z-axis of the sensor to be calibrated (5) are both set horizontally, and the y-axis is set upward. The center of gravity of the static weight standard component is located in the zy plane, which serves as the basic state of the sensor to be calibrated (5). Step 13, transform the gravity vector of the static standard component to the coordinate system of the sensor being calibrated (5): In the basic state, the force vector of the static weight standard component in the coordinate system of the sensor being calibrated (5) is: ； In the formula: G is the gravity acting on the statically weighed standard component; G 0x The component of gravity G on the x-axis of the sensor (5) being calibrated; G 0y Let G be the component of gravity G on the y-axis of the sensor (5) being calibrated; G 0z Let G be the component of gravity G along the z-axis of the sensor (5) being calibrated; In the basic state, the coordinates of the center of gravity of the static weight standard component in the coordinate system of the sensor being calibrated (5) are: ； In the formula: MG is the bending moment vector of the gravity acting on the static standard component relative to the center of the sensor (5) being calibrated; M 0x Let MG be the component of the sensor (5) being calibrated on the x-axis; M 0y Let MG be the component of MG on the y-axis of the sensor (5) being calibrated; M 0z Let MG be the z-axis component of the sensor (5) being calibrated; zG is the distance between the center of gravity of the static standard component and the center of the sensor (5) being calibrated in the z-axis direction; The agreement is to adjust the roll angle first. Then adjust the pitch angle. Then, the attitude rotation transformation matrix relative to the i-th displacement sequence of the basic state is: ； In the formula: Let be the rotation transformation matrix of the i-th displacement sequence; Let be the elementary rotation transformation matrix about the x-axis in the i-th displacement sequence; Let be the basic element rotation transformation matrix about the z-axis in the i-th displacement sequence; Let be the rotation angle around the x-axis in the i-th displacement sequence; Let be the rotation angle around the z-axis in the i-th displacement sequence; The force vector exerted by the static weight standard component on the calibrated sensor (5) under the i-th displacement sequence is: ； The torque vector exerted by the static weight standard component on the calibrated sensor (5) under the i-th displacement sequence is: ； in, The force along the x-axis in the i-th displacement state; The force along the y-axis in the i-th displacement state; The force along the z-axis in the i-th displacement state; Mxi is the torque about the x-axis in the i-th displacement state; Let be the torque about the y-axis in the i-th displacement state; Let be the torque about the z-axis in the i-th displacement state; Adjusting the roll angle and pitch angle During the transition process, ensure that the load on the sensor being calibrated (5) does not exceed the limit load of the sensor being calibrated (5); Step 14, Overload Determination: Verify whether the force vector and torque vector acting on the sensor (5) under each displacement state exceed 120% of the range. If they exceed, it is determined to be overloaded, and return to repeat step one. If they do not exceed, it is determined to be not overloaded, and proceed to the next step. Step 15: Based on the overload determination results, establish a calibration load table and determine the displacement sequence matrix as follows: ； In the formula, [P] is the calibration load matrix; M is the total number of transposition sequences; The force along the x-axis in the Mth displacement state; The force along the y-axis in the Mth displacement state; The force along the z-axis in the Mth displacement state; Let be the torque about the x-axis in the Mth displacement state; Let be the torque about the y-axis in the Mth displacement state; Let be the torque about the z-axis in the Mth displacement state; The specific steps for step two are as follows: Step 21, zeroing in the absence of the aforementioned static weight standard component: Disassemble the static weight standard component and finely adjust the roll angle according to a predefined displacement sequence using the pitch photoelectric encoder (12) and roll photoelectric encoder (8). and pitch angle After positioning, the zero-load output matrix of the sensor being calibrated (5) is collected as follows: ； In the formula, [U0] is the zero-load output matrix; The first element zero-load voltage signal is output for the Mth displacement state; The output is the second zero-load voltage signal of the Mth displacement state; The third element zero-load voltage signal is output for the Mth displacement state; The fourth element zero-load voltage signal is output for the Mth displacement state; The fifth element zero-load voltage signal is output under the Mth displacement state; The sixth element zero-load voltage signal is output for the Mth displacement state; Step 22, data acquisition with the aforementioned static weight standard component: Install the static weight standard assembly, and tighten the cone head of the mounting cone (3) into the conical countersunk hole of the static weight main standard (1) by screw (2) to achieve an interference fit. After tightening, remove the screw (2). The roll angle is finely adjusted according to the predefined displacement sequence via feedback from the pitch photoelectric encoder (12) and the roll photoelectric encoder (8). and pitch angle After positioning, the loaded output matrix of the sensor (5) under calibration is acquired: ； In the formula, [U] is the loaded output matrix; The first element load voltage signal output is for the Mth displacement state; The output is the second-order load voltage signal for the Mth displacement state; The third element load voltage signal is output for the Mth displacement state; The fourth element load voltage signal is output for the Mth displacement state; The fifth element load voltage signal is output under the Mth displacement state; The output is the sixth element load voltage signal for the Mth displacement state; The specific steps for step two are as follows: Step 31, Processing the voltage difference matrix: Based on the zero-load output and the loaded output obtained in step two, the voltage difference is calculated using the following formula: ； Based on the channel coupling relationship given by the sensor under test (5), channel coupling is performed, and the six-dimensional strain voltage output formulas of the sensor under test (5) are as follows: ； ； ； ； ； ； In the formula, The voltage signal output of the first channel of the sensor being calibrated (5); The voltage signal output of the second channel of the sensor being calibrated (5); The voltage signal output of the third channel of the sensor being calibrated (5); The voltage signal output of the fourth channel of the sensor being calibrated (5); The voltage signal output of the fifth channel of the sensor being calibrated (5); The voltage signal output of the sixth channel of the sensor being calibrated (5); ΔUx is the voltage signal output of the x component after channel coupling; The output is the voltage signal of the y component after channel coupling; The output is the voltage signal of the z-component after channel coupling; The voltage signal output of the Mx component after channel coupling; The voltage signal output of the My component after channel coupling; The output voltage signal of the Mz component after channel coupling; The corrected zero-point voltage difference matrix after coupling is: ； Step 32, calculate the formula for the sensor (5) being calibrated; Establish a six-variable first-order explicit linear formula model: ； in, It is a 6×6 matrix of undetermined coefficients; The matrix form is as follows: ； The load matrix-voltage difference matrix equations are established as follows: ； The undetermined coefficient matrix is ​​calculated using a multivariate fitting method.

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