Gravity angle sensor, calibration method thereof and gravity compensation method applying gravity angle sensor

Abstract

The invention provides a gravity angle sensor, a calibration method thereof and a gravity compensation method applying the gravity angle sensor, and belongs to the technical field of sensors and intelligent control. The sensor comprises a sensor frame, a flexible spring piece assembly, a mass block and a differential strain measurement unit, the flexible spring piece assembly is symmetrically connected with the mass block and the sensor frame, and the flexible spring piece assembly is configured to generate bending deformation perpendicular to the axial direction of the flexible spring piece assembly under the action of a gravity component; the differential strain measurement units are arranged on the convex side and the concave side when the flexible spring piece is bent and used for detecting the bending strain difference perpendicular to the axial direction. High-precision and real-time gravity compensation under a dynamic working condition is realized by calibrating a maximum strain difference value, measuring a current strain difference in real time, calculating a specific value and directly generating a gravity compensation amount without resolving an attitude angle and breaking through range limitation of a cosine function. According to the scheme, mechanical friction is eliminated, sensitivity and stability are improved, and the method is suitable for high-dynamic force control systems such as robots and precision platforms.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of ion trap quantum computing, and particularly relates to a gravity angle sensor, a calibration method thereof, and a gravity compensation method using the same. BACKGROUND

[0002] The polishing robot has been widely applied in many fields such as aviation equipment, high-speed rail interior, automobile and ship manufacturing, hardware and bathroom due to its good flexibility and large motion range. According to the robot dynamics, the maximum disturbance force in space for the mechanical arm is gravity. When the robot arm fights against gravity, the mass of the load and the arm link part will generate a gravity torque. In order to reduce the influence of the gravity torque on the motion control of the robot arm, it is necessary to improve the positioning accuracy of the actuator through gravity compensation.

[0003] In the prior art, gravity compensation usually depends on an attitude sensor (such as a gyroscope, IMU) to obtain the attitude angle θ of the device relative to the gravity direction, and then calculates the component of gravity in a certain axial direction through a trigonometric function operation to realize compensation. This method is essentially a static compensation model, which assumes that the system is in a static or quasi-static state and only considers the geometric projection component of gravity. However, in actual working conditions, the actuator is often in an acceleration or deceleration motion state, and the load is not only affected by gravity but also by inertia. At this time, the force signal measured by the sensor already contains the superposition of the gravity component and the dynamic inertia. The traditional angle-based compensation method cannot distinguish between the two and still calculates based on pure geometric angles, resulting in a deviation of the compensation value from the actual requirement and even introducing errors.

[0004] Therefore, how to provide a gravity angle sensor and a calibration method thereof that can meet the needs of high dynamic response scenarios, and a gravity compensation method using the same is a problem that those skilled in the art need to solve. SUMMARY

[0005] Therefore, the present application provides a gravity angle sensor and a calibration method thereof, and a gravity compensation method using the same, which can ensure that the internal state and all external states are decoupled at the end of the logic gate operation by slowly turning on and off the spin-dependent force using the adiabatic elimination principle.

[0006] To achieve the above object, the present application adopts the following technical solutions:

[0007] The present application first provides a gravity angle sensor for compensating the gravity component of a load acting on an electromechanical device, which comprises a sensor frame, a flexible spring sheet assembly, a differential strain measurement unit and a mass block, wherein the flexible spring sheet assembly is arranged on the sensor frame and comprises a plurality of flexible spring sheets arranged in parallel and connected in series, and the differential strain measurement unit is arranged on the sensor frame and comprises a plurality of strain gauges arranged in parallel and connected in series.

[0008] The sensor frame is rigidly connected with the electromechanical device, and the mass block is connected with the sensor frame through the flexible spring sheet assembly;

[0009] The flexible spring sheet assembly is fixed at two ends of the mass block in axial symmetry, and is configured to bend perpendicularly to the axial direction of the flexible spring sheet assembly under the action of the gravity component;

[0010] The differential strain measurement unit is arranged on the convex side and the concave side of the flexible spring sheet assembly where the bending deformation occurs; when the flexible spring sheet assembly bends, the differential strain measurement unit is used to measure the bending strain values on the convex side and the concave side.

[0011] Preferably, the differential strain measurement unit is arranged at symmetric positions on the convex side and the concave side of the bending deformation of the flexible spring sheet assembly, and the symmetric positions are the same cross-sectional positions in the axial direction of the flexible spring sheet assembly.

[0012] Preferably, the flexible spring sheet assembly includes a plurality of flexible spring sheets, and any flexible spring sheet has a convex side and a concave side when bending.

[0013] Preferably, the strain sensors of the differential strain measurement unit are arranged in pairs in a differential form at symmetric positions on the convex side and the concave side of the same flexible spring sheet of the flexible spring sheet assembly, and the symmetric positions are the same cross-sectional positions in the axial direction of the flexible spring sheet assembly.

[0014] Preferably, the strain sensors of the differential strain measurement unit are arranged in pairs in a differential form at symmetric positions on the convex side and the concave side of different flexible spring sheets of the flexible spring sheet assembly, and the symmetric positions are the same cross-sectional positions in the axial direction of the flexible spring sheet assembly.

[0015] Preferably, the flexible spring sheet assembly restricts the movement direction of the mass block to be perpendicular to the axial direction of the flexible spring sheet assembly.

[0016] When the angle between the axial direction of the flexible spring sheet assembly and the direction of gravity is 0° or 180°, the strain difference of the differential strain sensors arranged in pairs on the flexible spring sheet assembly is 0.

[0017] Preferably, the flexible spring sheet assembly restricts the movement direction of the mass block to be perpendicular to the axial direction of the flexible spring sheet assembly.

[0018] When the angle between the axial direction of the flexible spring sheet assembly and the direction of gravity is 90° or 270°, the strain difference of the differential strain sensors arranged in pairs on the flexible spring sheet assembly is a maximum value or a minimum value.

[0019] The application also provides a gravity compensation method based on the gravity angle sensor, applied to an electromechanical device with the gravity angle sensor, comprising the following steps:

[0020] S1: installing the gravity angle sensor on the electromechanical device, so that the included angle between the axial direction of the flexible spring sheet assembly and the direction of gravity is 90° or 270°, and recording the absolute value of the strain difference value output by the differential strain measurement unit at this time as the static maximum response value F max ;

[0021] S2: obtaining the current strain difference value F(t) output by the differential strain measurement unit in real time during the operation of the electromechanical device;

[0022] S3: directly calculating the gravity compensation amount f g (t) in the target direction based on the ratio of the current strain difference value F(t) to the static maximum response value F max , and the calculation formula is:

[0023]

[0024] Wherein, m is the load mass, and g is the gravity acceleration;

[0025] S4: inputting the gravity compensation amount f g (t) as a feedforward compensation item to the control system of the electromechanical device.

[0026] The application also provides a calibration method of the gravity angle sensor, comprising the following steps:

[0027] S100: taking the center of the gravity angle sensor as the center of a circle, taking the axial direction of the flexible spring sheet assembly as the length direction, controlling the gravity angle sensor to rotate one circle around the center of the circle, and obtaining the strain difference value change curve of the gravity angle sensor at each angle by using the differential strain measurement unit; wherein the maximum value, the minimum value and the zero-crossing point of the strain difference value change curve correspond to a plurality of standard reference angles;

[0028] S200: obtaining the strain difference values corresponding to the plurality of standard reference angles respectively according to the differential values of the strain difference value change curve at the zero-crossing points;

[0029] S300: calibrating the gravity angle sensor based on the plurality of standard reference angles and the strain difference values corresponding thereto.

[0030] Preferably, the plurality of standard reference angles include 0°, 90°, 180° and 270°.

[0031] Compared with the traditional gravity angle sensor and the compensation method thereof, the application has the following advantages:

[0032] The gravity angle sensor of the application adopts a differential strain measurement unit, which is arranged at the symmetrical position of the convex side and the concave side of the flexible spring sheet, detects the strain of the convex side and the concave side, fully utilizes the low stiffness characteristic of the structure in the bending direction, and can generate significant deformation and strain under a small external force, so that the real mechanical state can be effectively reflected and the sensitivity can be improved.

[0033] The traditional method depends on the attitude sensor to calculate the angle θ, and then calculates the compensation amount through θ, only reflects the geometric projection of the gravity, and cannot perceive the inertial force caused by the system acceleration. The gravity compensation method provided by the application breaks through the limitation of static compensation, directly utilizes the bending strain response of the flexible spring sheet under the joint action of the gravity and the inertial force, generates the compensation amount through the mechanical parameter ratio operation, and naturally contains the dynamic load information. Even in the non-steady state working conditions such as acceleration rising, deceleration descending or vibration impact, the compensation value matched with the actual stress can still be output, and the dynamic response accuracy and stability of the force control system are significantly improved.

[0034] In the traditional method, cosθ∈[-1, 1], so that the compensation amount is limited in the range of [-mg, mg]. When the system accelerates upward, the actual required compensation force is greater than mg, and the traditional method cannot express this state, resulting in under-compensation; when the system accelerates downward, the compensation is easy to be over-compensated. In the application, the mechanical parameter ratio can be greater than 1 or less than -1, which can truly reflect the “overweight” and “weightlessness” states, so that the compensation amount is always consistent with the actual mechanical demand of the system.

[0035] The traditional method needs to perform nonlinear trigonometric function operations such as arccos and cos, which is complex and time-consuming in calculation, and is difficult to meet the high-frequency force control demand. The application adopts linear ratio operation, does not need to solve the angle through inverse trigonometric function, and does not need to calculate the trigonometric function again, only needs once division and multiplication operation, can be completed in real time on the microcontroller or FPGA, effectively shortens the control period, and improves the system bandwidth. BRIEF DESCRIPTION OF DRAWINGS

[0036] In order to more clearly illustrate the technical solutions in the embodiments of the application or the prior art, the following will briefly introduce the drawings needed to be used in the embodiment or prior art description. Obviously, the drawings in the following description are only embodiments of the application, and other drawings can be obtained by those skilled in the art without creative labor on the basis of the provided drawings.

[0037] Figure 1 The overall structure schematic diagram of the gravity angle sensor provided by the embodiment of the application is shown in the figure;

[0038] Figure 2A working schematic diagram of a gravity angle sensor provided by the embodiment of the present application in a horizontal case and a local enlarged view;

[0039] Figure 3 A working schematic diagram of a gravity angle sensor provided by the embodiment of the present application in a vertical case;

[0040] Figure 4 A working schematic diagram of a gravity angle sensor provided by the embodiment of the present application in a case with an inclination angle of α;

[0041] Figure 5 A first difference distribution schematic diagram of a strain sensor in a gravity angle sensor provided by the embodiment of the present application;

[0042] Figure 6 A second difference distribution schematic diagram of a strain sensor in a gravity angle sensor provided by the embodiment of the present application;

[0043] Figure 7 A third difference distribution schematic diagram of a strain sensor in a gravity angle sensor provided by the embodiment of the present application;

[0044] Figure 8 A fourth difference distribution schematic diagram of a strain sensor in a gravity angle sensor provided by the embodiment of the present application;

[0045] Figure 9 A gravity compensation method flow schematic diagram of a gravity angle sensor provided by the embodiment of the present application;

[0046] Figure 10 A calibration method flow schematic diagram of a gravity angle sensor provided by the embodiment of the present application. DETAILED DESCRIPTION

[0047] The technical solutions in the embodiments of the present application will be described clearly and completely below with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative work fall within the scope of protection of the present application.

[0048] The first aspect of the embodiment of the present application provides a gravity angle sensor for compensating for a gravity component acting on a machine electric device, the gravity angle sensor comprising: a sensor frame 1, a flexible spring sheet assembly 2, a differential strain measurement unit 4 and a mass block 3; the sensor frame 1 is rigidly connected with the machine electric device, and the mass block 3 is connected with the sensor frame 1 through the flexible spring sheet assembly 2; the flexible spring sheet assembly 2 is fixed at two ends of the mass block 3 in an axial symmetry manner, and the flexible spring sheet assembly 2 is configured to generate a bending deformation perpendicular to the axial direction of the flexible spring sheet assembly 2 under the action of the gravity component; the differential strain measurement unit 4 is arranged on the deformation convex side and the deformation concave side of the flexible spring sheet assembly 2 where the bending deformation occurs; and the differential strain measurement unit 4 is used for measuring the bending strain values on the deformation convex side and the deformation concave side when the bending deformation of the flexible spring sheet assembly 2 occurs.

[0049] In one embodiment, referring to Figure 1 , the sensor frame 1 adopts a "concave" structure, and the mass block 3 is fixedly connected at the middle position of the two vertical rods of the "concave" structure through the flexible spring sheet assembly 2.

[0050] In one embodiment, referring to Figure 1 and Figure 2 , the differential strain measurement unit 4 is arranged at the symmetric positions of the deformation convex side and the deformation concave side of the bending deformation of the flexible spring sheet assembly 2, and the symmetric positions are the same cross-sectional positions along the axial direction of the flexible spring sheet assembly 2. Arranging and installing the strain sensors 41 in a differential form can reduce the strain measurement errors caused by temperature, zero drift and other factors.

[0051] In one embodiment, the flexible spring sheet assembly 2 comprises a plurality of flexible spring sheets 21, and any flexible spring sheet 21 has a deformation convex side and a deformation concave side when generating a bending deformation.

[0052] In the embodiment, the strain sensors 41 of the differential strain measurement unit 4 are arranged in pairs in a differential form at the symmetric positions of the deformation convex side and the deformation concave side of the same flexible spring sheet 21 of the flexible spring sheet assembly 2, and the symmetric positions are the same cross-sectional positions along the axial direction of the flexible spring sheet assembly 2.

[0053] In the embodiment, the strain sensors 41 of the differential strain measurement unit 4 are arranged in pairs in a differential form at the symmetric positions of the deformation convex side and the deformation concave side of different flexible spring sheets 21 of the flexible spring sheet assembly 2, and the symmetric positions are the same cross-sectional positions along the axial direction of the flexible spring sheet assembly 2.

[0054] In the above two cases, in the specific implementation, the flexible spring sheet assembly 2 comprises: a first spring sheet unit and a second spring sheet unit symmetrically arranged relative to the mass 3; the first spring sheet unit and the second spring sheet unit each comprise at least two flexible spring sheets 21, and any flexible spring sheet 21 has a deformation convex side and a deformation concave side when generating a bending deformation. The strain sensors 41 of the differential strain measurement unit 4 are arranged in pairs in a differential form on the deformation convex side and the deformation concave side of the same flexible spring sheet at the same axial (length) position of the flexible spring sheet (as shown in Figures 1-4 FIG. 2) or arranged in pairs in a differential form on the stretching side and the compression side of different flexible spring sheets at the same axial (length) position of the flexible spring sheet (as shown in Figures 5-8 FIG. 3).

[0055] The strain sensor 41 in the gravity angle sensor provided by the application can also be in the form of a plurality of groups of differential strain measurement units arranged on the symmetrically arranged flexible spring sheets 21; each group of differential strain measurement units comprises a pair of differential strain sensors 41. The strain sensors 41 of each group of differential strain measurement units are respectively arranged on the deformation convex side and the deformation concave side of the corresponding flexible spring sheet 21 when generating a bending deformation (as shown in Figures 7-8 FIG. 4).

[0056] In an embodiment, the movement direction of the mass 3 constrained by the flexible spring sheet assembly 2 is perpendicular to the axial direction of the flexible spring sheet assembly 2. The flexible spring sheet is an elongated structure, the length direction of the elongated structure is the axial direction, and the axial stiffness coefficient is much larger than the stiffness coefficient perpendicular to the axial direction. Under the action of a non-axial external force, the elongated structure will generate a bending deformation, the two ends are fixed, and a transverse displacement is generated in the middle. This bending will cause the side opposite to the bottom of the elongated structure to protrude and be subjected to tension, and the side opposite to the top of the elongated structure to be recessed and be subjected to compression, which is the basis for differential strain measurement.

[0057] When the included angle between the axial direction of the flexible spring sheet assembly 2 and the gravity direction is 0° or 180°, the movement direction of the mass 3 overlaps with the gravity direction, the gravity component of the mass 3 in the gravity direction is 0, the mass 3 cannot generate a bending deformation under the action of gravity, the bending strain values of the deformation convex side and the deformation concave side are the same, and thus the strain differential value of the differential strain sensor 41 arranged in pairs on the flexible spring sheet assembly 2 is 0.

[0058] When the angle between the axial direction of the flexible spring sheet assembly 2 and the direction of gravity is 90° or 270°, the direction of movement of the mass 3 is perpendicular to the direction of gravity, the gravity component in the direction of movement reaches a maximum or minimum value, and the mass 3 causes the flexible spring sheet 21 to generate bending strains in opposite directions on the convex side and the concave side of deformation under the action of gravity. In this case, the strain difference value of the differential strain sensor 41 arranged in pairs on the flexible spring sheet assembly 2 reaches a maximum or minimum value.

[0059] When the angle between the axial direction of the flexible spring sheet 21 and the direction of gravity is other values, the gravity component in the direction of movement of the mass 3 is between the maximum and minimum values in the above case ②. Correspondingly, in this case, the strain difference value of the differential strain sensor 41 arranged in pairs on the flexible spring sheet 21 is also between the maximum and minimum values in case ②.

[0060] Further, in combination with Figures 2-4 The working principle of the gravity angle sensor is described in detail as follows:

[0061] As shown in Figure 2 When the angle between the axial direction of the flexible spring sheet 21 in the gravity angle sensor and the direction of gravity (-Y direction) is 90° or 270°, the mass 3 causes the flexible spring sheet 21 to generate bending strains in opposite directions on the convex side and the concave side of deformation under the action of gravity. In this case, the gravity component of the mass 3 in the direction of movement (-Y direction) reaches a maximum or minimum value, and the strain difference value of the differential strain sensor 41 arranged on the flexible spring sheet 21 reaches a maximum or minimum value.

[0062] As shown in Figure 3 When the angle between the axial direction of the flexible spring sheet 21 in the gravity angle sensor and the direction of gravity (-Y direction) is 0° or 180°, the direction of movement of the mass 3 overlaps with the direction of gravity (X direction), the gravity component in the direction of gravity is 0, and the bending strain values on the convex side and the concave side of deformation are the same, so that the strain difference value of the differential strain sensor 41 arranged on the flexible spring sheet 21 is 0.

[0063] As shown in Figure 4 When the angle between the axial direction of the flexible spring sheet 21 in the gravity angle sensor and the direction of gravity (-Y direction) is 90°-α, that is, the angle between the direction of movement of the mass 3 and the direction of gravity (-Y direction) is α, the gravity component of the mass 3 in the direction of movement is between the maximum and minimum values in the case shown in Figure 2 Correspondingly, in this case, the strain difference value of the differential strain sensor 41 arranged on the flexible spring sheet 21 is also between the maximum and minimum values in the case shown in Figure 2 According to the strain difference value in this case and Figure 2The differential strain extreme value in the case shown can be conveniently obtained as the angle between the length direction of the flexible spring sheet 21 and the gravity direction (-Y direction) in this case.

[0064] The second aspect of the embodiment of the application provides a gravity compensation method of a gravity angle sensor according to the gravity angle sensor of the first aspect of the embodiment, as shown in the method, comprising the following steps: Figure 9

[0065] S1: installing the gravity angle sensor on the electromechanical device, so that the angle between the axial direction of the flexible spring sheet assembly 2 and the gravity direction is 90° or 270°, and recording the absolute value of the differential strain value output by the differential strain measuring unit 4 at this time as the static maximum response value F max ;

[0066] S2: obtaining the current differential strain value F(t) output by the differential strain measuring unit 4 in real time during the operation of the electromechanical device;

[0067] S3: directly calculating the gravity compensation amount f g (t) in the target direction based on the ratio of the current differential strain value F(t) to the static maximum response value F max , and the calculation formula is:

[0068]

[0069] Wherein, m is the load mass, and g is the gravity acceleration;

[0070] It should be noted that the gravity compensation process considers the gravity compensation amount f g = mg*cos(θ), and the conventional method needs to first measure the angle θ through the attitude sensor and then substitute the cosine function to calculate the compensation force. θ as a geometric angle represents the static attitude of the object in space, and its physical meaning is the angle between the directions. cos(θ) or sin(θ) as a normalized proportion coefficient of the gravity component only reflects the projection of the gravity in the space direction and does not contain any dynamic information. The threshold range of cos(θ) or sin(θ) is [-1, 1], and in the dynamic scene:

[0071] For the system acceleration rising scene, the measured force = gravity + inertial force (upward acceleration), the actual force > mg, but cos(θ) is still ≤1, which makes the calculated f g (t) ≤ mg, resulting in insufficient compensation.

[0072] For the system acceleration descending scene, the measured force = gravity - inertial force (downward acceleration), the actual force < mg, but cos(θ) is still ≥-1, which makes the calculated f g (t) ≥-mg, resulting in excessive compensation.​

[0073] The method embodiment proposes a brand-new gravity compensation method which directly processes in the force domain and retains all dynamic information in the measurement signal. Without calculation by angle inversion, the value range is not limited by [-1, 1], for example, when the system accelerates, F(t) will be greater than mg, at this time, the calculated f g (t) is naturally greater than mg, when the system decelerates, F(t) will be less than mg, at this time, the calculated f g (t) will also be naturally less than mg, which can truly reflect the enhancement effect of dynamic load and make the compensation more in line with the actual physical process. This is not only suitable for static or slow working conditions, but also can be effectively applied to complex dynamic scenes with high acceleration and variable load.

[0074] S4: input the gravity compensation amount f g (t) as a feedforward compensation item to the control system of the electromechanical device.

[0075] The third aspect of the embodiment of the application provides a calibration method of a gravity angle sensor according to the gravity angle sensor of the first aspect of the embodiment, as shown in the figure, comprising the following steps: Figure 10

[0076] S100: taking the center of the gravity angle sensor as the center and the axial direction of the flexible spring sheet assembly 2 as the radial direction, rotating the gravity angle sensor around the center for one revolution, and obtaining a strain difference value change curve of the gravity angle sensor at each angle by using the differential strain measurement unit 4; wherein the maximum value, the minimum value and the zero-crossing point of the strain difference value change curve correspond to a plurality of standard reference angles;

[0077] S200: obtaining the strain difference values corresponding to the plurality of standard reference angles respectively according to the differential values of the strain difference value change curve at the zero-crossing points;

[0078] S300: calibrating the gravity angle sensor based on the plurality of standard reference angles and the strain difference values corresponding thereto.

[0079] In one embodiment, the plurality of standard reference angles include 0°, 90°, 180° and 270°.

[0080] ​In combination with the sensor design scheme in the above embodiment one, the calibration method in the present embodiment can be: controlling the gravity angle sensor to rotate one circle around the axis, and using the differential strain sensor 41 to obtain the strain differential value change curve of the gravity angle sensor at each angle. The maximum and minimum values of the above strain differential value curve correspond to the case that the length direction of the flexible spring sheet 21 in the gravity angle sensor and the gravity direction are at 90° or 270°; the zero-crossing point of the above strain differential value curve corresponds to the case that the length direction of the flexible spring sheet 21 in the gravity angle sensor and the gravity direction are at 0° or 180°; and the positive and negative of the differential value of the above strain differential value curve at the zero-crossing point can be used to conveniently obtain the strain differential values corresponding to the above angles of 0°, 90°, 180° and 270°. The above four sets of angles and strain differential values can be used to conveniently calibrate the gravity angle sensor proposed in the present application.

[0081] The gravity angle sensor and the calibration method thereof and the gravity compensation method using the same provided in the present application are described in detail above, and the principles and implementation manners of the present application are described by using specific examples in the present embodiment, and the above embodiment description is only used to help understand the method of the present application and the core idea thereof; meanwhile, for the ordinary skilled in the art, the specific implementation manners and application ranges will be changed according to the idea of the present application, and in summary, the content of the present description should not be understood as a limitation on the present application.

[0082] The above description of the disclosed embodiments enables a person skilled in the art to implement or use the present application. Various modifications to these embodiments will be apparent to those skilled in the art, and the general principles defined in the present embodiment can be implemented in other embodiments without departing from the spirit or scope of the present application. Therefore, the present application will not be limited to the embodiments shown in the present embodiment, but will conform to the widest scope consistent with the principles and novel features disclosed in the present embodiment.

Claims

1. A gravity angle sensor, characterized by, The gravity angle sensor is used to compensate the gravity component of the load acting on the electromechanical device, and the gravity angle sensor comprises a sensor frame, a flexible spring sheet assembly, a differential strain measurement unit and a mass block; wherein, The sensor frame is rigidly connected with the electromechanical device, and the mass block is connected with the sensor frame through the flexible spring sheet assembly; The flexible spring sheet assembly is fixed at both ends of the mass block along the axial direction, and the flexible spring sheet assembly is configured to bend perpendicularly to the axial direction of the flexible spring sheet assembly under the action of the gravity component; The differential strain measurement unit is arranged on the convex side and the concave side of the bending deformation of the flexible spring sheet assembly; when the flexible spring sheet assembly bends, the differential strain measurement unit is used to measure the bending strain values on the convex side and the concave side.

2. A gravity angle sensor according to claim 1, characterised in that The differential strain measurement unit is arranged at the symmetric positions of the convex side and the concave side of the bending deformation of the flexible spring sheet assembly, and the symmetric positions are the same cross-sectional positions along the axial direction of the flexible spring sheet assembly.

3. A gravity angle sensor according to claim 1, wherein The flexible spring sheet assembly comprises a plurality of flexible spring sheets, and any flexible spring sheet has a convex side and a concave side when bending.

4. A gravity angle sensor according to claim 3, wherein The strain sensors of the differential strain measurement unit are arranged in pairs in a differential form at the symmetric positions of the convex side and the concave side of the same flexible spring sheet of the flexible spring sheet assembly along the axial direction of the flexible spring sheet assembly.

5. A gravity angle sensor according to claim 3, wherein The strain sensors of the differential strain measurement unit are arranged in pairs in a differential form at the symmetric positions of the convex side and the concave side of different flexible spring sheets of the flexible spring sheet assembly along the axial direction of the flexible spring sheet assembly.

6. A gravity angle sensor according to claim 1, wherein The flexible spring sheet assembly restricts the movement direction of the mass block to be perpendicular to the axial direction of the flexible spring sheet assembly; When the included angle between the axial direction of the flexible spring sheet assembly and the direction of gravity is 0° or 180°, the strain difference of the differential strain sensors arranged in pairs on the flexible spring sheet assembly is 0.

7. A gravity angle sensor according to claim 1, wherein The flexible spring sheet assembly restricts the movement direction of the mass block to be perpendicular to the axial direction of the flexible spring sheet assembly; When the included angle between the axial direction of the flexible spring sheet assembly and the direction of gravity is 90° or 270°, the strain difference of the differential strain sensors arranged in pairs on the flexible spring sheet assembly is a maximum value or a minimum value.

8. A gravity compensation method based on the gravity angle sensor according to any one of claims 1-7, characterized in that, The application is applied to the electromechanical device with the gravity angle sensor, and comprises the following steps: S1: install the gravity angle sensor on the electromechanical device, so that the included angle between the axial direction of the flexible spring sheet assembly and the direction of gravity is 90° or 270°, and record the absolute value of the strain difference value output by the differential strain measuring unit at this time as the static maximum response value F max ; S2: acquiring the current strain difference value F(t) output by the differential strain measurement unit in real time during the operation of the electromechanical device; S3: based on the ratio of the current strain difference value F(t) and the static maximum response value F max , directly calculate the gravity compensation amount f g (t) in the target direction, the calculation formula is: Wherein, m is the mass of the load, and g is the acceleration of gravity; S4: the gravity compensation amount f is added to the control signal g (t) as a feedforward compensation term to the control system of the electromechanical device.

9. A method of calibrating a gravity angle sensor according to any one of claims 1-8, characterized in that, The application comprises the following steps: S100: taking the center of the gravity angle sensor as the center of a circle and the axial direction of the flexible spring sheet assembly as the radial direction, rotating the gravity angle sensor around the center of the circle for one revolution, and acquiring the strain difference value change curve of the gravity angle sensor at each angle by using the differential strain measurement unit; wherein, the maximum value, the minimum value and the zero-crossing point of the strain difference value change curve correspond to a plurality of standard reference angles. S200: obtaining strain difference values corresponding to a plurality of standard reference angles respectively according to the differential value of the strain difference value curve at the zero-crossing point; S300: calibrating the gravity angle sensor based on the plurality of standard reference angles and the strain difference values corresponding thereto.

10. The method of calibrating a gravity angle sensor of claim 9, wherein, The plurality of standard reference angles include 0°, 90°, 180° and 270°.

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