Capacitive six-dimensional force sensor

Abstract

The invention provides a capacitive six-dimensional force sensor. The capacitive six-dimensional force sensor comprises a stress assembly and an induction capacitor assembly, the induction capacitor assembly is detachably connected with the stress assembly; the stress assembly is used for transmitting force to the induction capacitor assembly when being stressed; the inductive capacitor assembly is used for outputting each square wave signal under the action of the force, and the frequency of the square wave signal and the six-dimensional component of the force have a linear matrix relationship, so that the acquisition precision of the capacitive six-dimensional force sensor is improved, and the cost of the capacitive six-dimensional force sensor is reduced.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of force sensors, in particular to a capacitive six-dimensional force sensor. BACKGROUND

[0002] With the development trend of robots and environment being more and more closely integrated, the six-dimensional force sensor can make the robot more intelligent and safer to interact with the environment and human beings by providing multi-dimensional force and torque feedback, and significantly improve the reliability, adaptability and safety of the robot in complex tasks.

[0003] At present, there are mainly strain gauge type six-dimensional force sensors, capacitive six-dimensional force sensors and grating type six-dimensional force sensors. Among them, the strain gauge is easily affected by temperature drift, and a complex compensation circuit is needed to eliminate the temperature drift. The structure of the strain gauge type six-dimensional force sensor is complex, and the precision of installation and debugging is required. The cost of the grating type six-dimensional force sensor is high, the signal processing process is complex, and the optical fiber is easily disturbed by environmental vibration. The capacitance of the capacitive force sensor is small, and a special integrated circuit (Application-Specific Integrated Circuit, ASIC) is needed, which is high in cost. The capacitance output by the capacitive six-dimensional force sensor has a nonlinear relationship with the force, and a complex structure design is needed to offset the nonlinear influence.

[0004] Therefore, the design of the six-dimensional force sensor in the prior art has certain limitations. SUMMARY

[0005] The purpose of the present application is to provide a capacitive six-dimensional force sensor to solve the problem of the design of the six-dimensional force sensor in the prior art having certain limitations.

[0006] To achieve the above purpose, the technical solutions adopted by the embodiments of the present application are as follows: In a first aspect, the embodiments of the present application provide a capacitive six-dimensional force sensor, comprising: a force receiving assembly and a sensing capacitor assembly. The sensing capacitor assembly is detachably connected with the force receiving assembly. The force receiving assembly is used to transmit force to the sensing capacitor assembly when force is received. The sensing capacitor assembly is used to output square wave signals under the action of force, wherein the frequency of the square wave signal has a linear matrix relationship with the six-dimensional components of the force.

[0007] As an optional implementation manner, the sensing capacitor assembly comprises: an elastic component and a signal acquisition circuit board. The elastic component is detachably connected with the force receiving assembly. The elastic component is detachably connected with the signal acquisition circuit board, and a plurality of sensing capacitors are formed between the elastic component and the signal acquisition circuit board. The elastic component is used to generate deformation under the action of force and drive the signal acquisition circuit board to generate displacement. The signal acquisition circuit board is used to collect the capacitance value change of each sensing capacitor when generating displacement, and output the square wave signal corresponding to each sensing capacitor according to the capacitance value change of each sensing capacitor. The frequency of the square wave signal is used to represent the size of the six-dimensional component of the force.

[0008] As an optional implementation manner, the elastic component includes a flexible deformation body and a rigid support body. The flexible deformation body is detachably connected with the signal acquisition circuit board and the force receiving assembly, respectively. The rigid support body is arranged at the outer periphery of the flexible deformation body, and is used to fix the boundary of the flexible deformation body. The flexible deformation body is used to generate deformation under the action of force and drive the signal acquisition circuit board to generate displacement.

[0009] As an optional implementation manner, the flexible deformation body is detachably connected with the force receiving assembly through a plurality of bolts. The flexible deformation body is detachably connected with the signal acquisition circuit board through a plurality of screws.

[0010] As an optional implementation manner, the signal acquisition circuit board includes a plurality of first acquisition circuits. Each first acquisition circuit is used to collect the capacitance value change of each sensing capacitor when the signal acquisition circuit board generates displacement, and output the square wave signal corresponding to each sensing capacitor according to the capacitance value change of each sensing capacitor.

[0011] As an optional implementation manner, the signal acquisition circuit board further includes a second acquisition circuit and a circuit board bridge, and the circuit board bridge includes a reference capacitor. The second acquisition circuit is used to collect the capacitance value of the reference capacitor, and output the reference square wave signal corresponding to the reference capacitor according to the capacitance value of the reference capacitor. The reference square wave signal is used for temperature compensation and / or base point compensation.

[0012] As an optional implementation manner, the elastic component further includes a plurality of elastic body protrusions. When the elastic component is detachably connected with the signal acquisition circuit board, each elastic body protrusion is located at the outer periphery of the circuit board bridge. Each elastic body protrusion is used to shield electromagnetic interference for the circuit board bridge.

[0013] As an optional implementation, the rigid support body comprises a plurality of first vertical capacitor plates and a plurality of first flat capacitor plates arranged adjacent to each of the first vertical capacitor plates.

[0014] As an optional implementation, the signal acquisition circuit board further comprises a plurality of second vertical capacitor plates and a plurality of second flat capacitor plates arranged adjacent to each of the second vertical capacitor plates.

[0015] As an optional implementation, the first vertical capacitor plates and the second vertical capacitor plates form a first induced capacitance. The first flat capacitor plates and the second flat capacitor plates form a second induced capacitance.

[0016] The application has the following beneficial effects: The application provides a capacitive six-dimensional force sensor, which comprises a force receiving assembly and an induced capacitance assembly. The force receiving assembly is a component directly subjected to external force. The induced capacitance assembly is detachably connected with the force receiving assembly. The force receiving assembly transmits force to the connected induced capacitance assembly when subjected to force. The induced capacitance assembly deforms under the action of the force transmitted by the force receiving assembly, so that the capacitance values sensed by the induced capacitance assembly change, and then square wave signals corresponding to each induced capacitance are output. The frequency of the square wave signal has a linear matrix relationship with the six-dimensional components of the force. The six-dimensional components of the force are accurately calculated through the linear matrix relationship between the frequency of the square wave signal and the six-dimensional components of the force, the collection accuracy of the capacitive six-dimensional force sensor is improved, and the cost of the capacitive six-dimensional force sensor is reduced. BRIEF DESCRIPTION OF DRAWINGS

[0017] In order to more clearly illustrate the technical solutions of the embodiments of the application, the following will briefly introduce the drawings needed to be used in the embodiments. It should be understood that the following drawings only show some embodiments of the application, and therefore should not be regarded as a limitation on the scope. For those skilled in the art, other related drawings can also be obtained without creative labor on the basis of these drawings.

[0018] Figure 1 Structure diagram of the capacitive six-dimensional force sensor provided by the embodiments of the application Figure 1 ; Figure 2 Structure diagram of the capacitive six-dimensional force sensor provided by the embodiments of the application Figure 2 ; Figure 3 Structure diagram of the capacitive six-dimensional force sensor provided by the embodiments of the application Figure 3 ; Figure 4 Structure diagram of the capacitive six-dimensional force sensor provided by the embodiments of the application Figure 4 ; Figure 5 Structure diagram of the capacitive six-dimensional force sensor provided by the embodiment of the present application Figure 5 ; Figure 6 Structure diagram of the capacitive six-dimensional force sensor provided by the embodiment of the present application Figure 6 ; Figure 7 Structure diagram of the capacitive six-dimensional force sensor provided by the embodiment of the present application Figure 7 ; Figure 8 Structure diagram of the capacitive six-dimensional force sensor provided by the embodiment of the present application Figure 8 ; Figure 9 Structure diagram of the capacitive six-dimensional force sensor provided by the embodiment of the present application Figure 9 ; Figure 10 Structure diagram of the first acquisition circuit provided by the embodiment of the present application Figure 1 ; Figure 11 Structure diagram of the first acquisition circuit provided by the embodiment of the present application Figure 2 ; Figure 12 Waveform diagram of the charging and discharging time of the square wave signal and the variable capacitor provided by the embodiment of the present application Figure 13 Structure diagram of the first acquisition circuit provided by the embodiment of the present application Figure 3 .

[0019] Reference signs: force receiving assembly: 10; inductive capacitance assembly: 20; elastic component: 21; signal acquisition circuit board: 22; flexible deformation body: 211; rigid support body: 212; first acquisition circuit: 221; second acquisition circuit: 222; circuit board bridge: 223; elastic body protrusion: 213; first vertical capacitor plate: 2121; first horizontal capacitor plate: 2122; second vertical capacitor plate: 224; second horizontal capacitor plate: 225; first comparator: U1; second comparator: U2; first resistor: R1; second resistor: R2; third resistor: R3; fourth resistor: R4; fifth resistor: R5; variable inductive capacitor: Cx. DETAILED DESCRIPTION

[0020] To make the objectives, technical solutions, and advantages of the embodiments of the present application clearer, the following will be combined with the accompanying drawings for the embodiments of the present application to make a clear and complete description of the technical solutions in the embodiments of the present application. It should be understood that the accompanying drawings in the present application are only for the purpose of illustration and description, and are not used to limit the scope of the present application. In addition, it should be understood that the schematic drawings are not drawn according to the actual proportions. The flowcharts used in the present application show the operations implemented according to some embodiments of the present application. It should be understood that the operations of the flowcharts can not be implemented in sequence, and the steps without logical context relationship can be reversed in sequence or implemented simultaneously. In addition, one or more other operations can be added to the flowcharts or one or more operations can be removed from the flowcharts under the guidance of the content of the present application.

[0021] In addition, the described embodiments are only some of the embodiments of the present application, not all the embodiments. The components of the embodiments of the present application described and shown in the accompanying drawings can be arranged and designed in various different configurations. Therefore, the following detailed description of the embodiments of the present application provided in the accompanying drawings is not intended to limit the scope of the claimed present application, but only represents selected embodiments of the present application. Based on the embodiments of the present application, all other embodiments obtained by those skilled in the art without creative labor are within the scope of protection of the present application.

[0022] It should be noted that the term "comprising" will be used in the embodiments of the present application to indicate the presence of the features declared thereafter, but does not exclude the addition of other features.

[0023] In the field of force sensors, mainly include strain gauge type six-axis force sensor, capacitive six-axis force sensor and grating type six-axis force sensor. Among them, the strain gauge is easily affected by temperature drift, and a complex compensation circuit is needed to eliminate temperature drift, and the structure of the strain gauge type six-axis force sensor is complex, and the precision of installation and debugging is required. The cost of the grating type six-axis force sensor is high, the signal processing process is complex, and the optical fiber is easily disturbed by environmental vibration. The capacitance of the capacitive force sensor is small, and ASIC is needed, the cost is high, and the capacitance output by the capacitive six-axis force sensor has a nonlinear relationship with the force, which needs to be offset by complex structure design. That is, the design of the six-axis force sensor in the prior art has certain limitations.

[0024] The embodiment of the present application provides a capacitive six-dimensional force sensor based on the above problem. When the capacitive six-dimensional force sensor is subjected to force, slight deformation occurs, so that the capacitance of the sensing capacitor changes, and then the frequency of the output square wave signal corresponding to the sensing capacitor changes. The frequency change of the square wave signal corresponding to the sensing capacitor is decoupled from the force, and a linear matrix relationship between the frequency of the square wave signal and six-dimensional components of the force is obtained. The six-dimensional components of the force are accurately calculated based on the linear matrix relationship between the frequency of the square wave signal and the six-dimensional components of the force, the collection accuracy of the capacitive six-dimensional force sensor is improved, and the cost of the capacitive six-dimensional force sensor is reduced.

[0025] Figure 1 The capacitive six-dimensional force sensor provided by the embodiment of the present application Figure 1 As shown in Figure 1 , the capacitive six-dimensional force sensor comprises a force receiving assembly 10 and a sensing capacitor assembly 20.

[0026] The sensing capacitor assembly 20 is detachably connected with the force receiving assembly 10; the force receiving assembly 10 is used for transmitting force to the sensing capacitor assembly 20 when subjected to force.

[0027] Optionally, referring to Figure 1 , the force receiving assembly 10 in the capacitive six-dimensional force sensor is a component directly subjected to external force, the sensing capacitor assembly 20 is detachably connected with the force receiving assembly 10, and the force receiving assembly 10 transmits force to the connected sensing capacitor assembly 20 when subjected to force.

[0028] Specifically, the force receiving assembly 10 is provided with a plurality of screw holes (not shown in the figure) at the bottom, which are used for installing load force. The force receiving assembly 10 can also bear force at any position and transmit the force to the sensing capacitor assembly 20. Figure 1

[0029] The sensing capacitor assembly 20 is used for outputting square wave signals under the action of force, wherein the frequency of the square wave signal has a linear matrix relationship with the six-dimensional components of the force.

[0030] Optionally, continuing to refer to Figure 2 , the sensing capacitor assembly 20 deforms under the action of the force transmitted by the force receiving assembly 10, so that the capacitance sensed by the sensing capacitor assembly 20 changes, and then the square wave signals corresponding to each sensing capacitor are output, wherein the frequency of the square wave signal has a linear matrix relationship with the six-dimensional components of the force.

[0031] ​Specifically, the high level duration of the square wave signal is the charging time of the sensing capacitor, and the low level duration of the square wave signal is the discharging time of the sensing capacitor. When the capacitance of the sensing capacitor changes, the high level duration of the square wave signal corresponding to the sensing capacitor also changes accordingly. That is, when the capacitance of the sensing capacitor increases, the high level duration of the square wave signal becomes longer, and the frequency of the square wave signal becomes lower.

[0032] The least square based calibration matrix inversion algorithm can be used to decouple the linear matrix relationship between the frequency of the square wave signal and the six-dimensional component of the force. When the six-dimensional component of the force is subsequently solved, the linear matrix relationship and the frequency of the square wave signal output under the action of the force can be used to quickly solve the six-dimensional component of the force.

[0033] In the embodiment, the capacitive six-dimensional force sensor includes a force receiving assembly and a sensing capacitor assembly. The force receiving assembly is a component directly subjected to external force. The sensing capacitor assembly is detachably connected with the force receiving assembly. The force receiving assembly transmits force to the connected sensing capacitor assembly when subjected to force. The sensing capacitor assembly deforms under the action of the force transmitted by the force receiving assembly, so that the capacitances sensed by the sensing capacitor assembly change, and square wave signals corresponding to the sensing capacitors are output. The frequency of the square wave signal and the six-dimensional component of the force have a linear matrix relationship. The six-dimensional component of the force is accurately calculated through the frequency of the square wave signal and the linear matrix relationship between the six-dimensional component of the force, so as to improve the collection accuracy of the capacitive six-dimensional force sensor and reduce the cost of the capacitive six-dimensional force sensor.

[0034] As an optional implementation manner, as shown in Figure 1 The sensing capacitor assembly 20 includes an elastic component 21 and a signal acquisition circuit board 22.

[0035] The elastic component 21 is detachably connected with the force receiving assembly 10, and the elastic component 21 is detachably connected with the signal acquisition circuit board 22. A plurality of sensing capacitors are formed between the elastic component 21 and the signal acquisition circuit board 22.

[0036] Optionally, continuing to refer to Figure 2 The sensing capacitor assembly 20 includes the elastic component 21 and the signal acquisition circuit board 22. The elastic component 21 is detachably connected with the force receiving assembly 10, and the elastic component 21 is detachably connected with the signal acquisition circuit board 22.

[0037] A plurality of sensing capacitors are formed between the elastic component 21 and the signal acquisition circuit board 22. A plurality of elastic component electrodes exist on the elastic component 21, and a plurality of circuit board electrodes exist on the signal acquisition circuit board 22. A plurality of sensing capacitors are formed between each elastic component electrode and each circuit board electrode. The capacitances of the sensing capacitors change with the variation of the distance d between the elastic component electrodes and the circuit board electrodes.

[0038] The elastic component 21 is used to produce deformation under the action of force and drive the signal acquisition circuit board 22 to produce displacement.

[0039] Optionally, the elastic component 21 produces slight deformation under the action of the force transmitted by the force receiving component 10, the deformation of the elastic component 21 drives the signal acquisition circuit board 22 connected thereto to produce slight displacement, and thus the pole distance d between the elastic component electrodes and the circuit board electrodes changes, and the capacitance values of the sensing capacitors formed between the elastic component electrodes and the circuit board electrodes also change with the pole distance d.

[0040] The signal acquisition circuit board 22 is used to collect the capacitance value change amount of each sensing capacitor when displacement is produced, and output square wave signals corresponding to each sensing capacitor according to the capacitance value change amount of each sensing capacitor, and the frequency of the square wave signals is used to represent the size of the six-dimensional component of the force.

[0041] Optionally, the signal acquisition circuit board 22 collects the capacitance value change amount of each sensing capacitor when the capacitance value changes with the pole distance d when slight displacement is produced, and outputs square wave signals corresponding to each sensing capacitor based on the capacitance value change amount of each sensing capacitor, so as to represent the size of the six-dimensional component of the force through the frequency of the square wave signals corresponding to each sensing capacitor.

[0042] Specifically, the six-dimensional component of the force is quickly solved based on the frequency of the square wave signals and the linear matrix relationship obtained by pre-decoupling.

[0043] In the embodiment, the sensing capacitor assembly includes an elastic component and a signal acquisition circuit board, the elastic component is detachably connected with the force receiving component; the elastic component is detachably connected with the signal acquisition circuit board, and a plurality of sensing capacitors are formed between the elastic component and the signal acquisition circuit board. The elastic component produces slight deformation under the action of the force transmitted by the force receiving component, the deformation of the elastic component drives the signal acquisition circuit board to produce slight displacement, and thus the capacitance values of the sensing capacitors formed between the elastic component and the signal acquisition circuit board also change. The signal acquisition circuit board collects the capacitance value change amount of each sensing capacitor when slight displacement is produced, and outputs square wave signals corresponding to each sensing capacitor based on the capacitance value change amount of each sensing capacitor, so as to represent the size of the six-dimensional component of the force through the frequency of the square wave signals corresponding to each sensing capacitor. The six-dimensional component of the force is accurately solved by collecting the capacitance value change amount of each sensing capacitor formed between the elastic component and the signal acquisition circuit board.

[0044] Figure 2 Structure diagram of the capacitive six-dimensional force sensor provided by the embodiment Figure 2 As shown in Figure 2 , the elastic component 21 includes a flexible deformation body 211 and a rigid support body 212.

[0045] Optionally, referring to Figure 2 , the elastic component 21 includesFigure 2 The flexible deformation body 211 is inside the middle red line, and the rigid support body 212 is outside the red line.

[0046] The flexible deformation body 211 is detachably connected with the signal acquisition circuit board 22 and the force receiving assembly 10 respectively.

[0047] Optionally, continuing to refer to Figure 3 The flexible deformation body 211 is detachably connected with the force receiving assembly 10 to receive the force transmitted from the force receiving assembly 10. The flexible deformation body 211 is also detachably connected with the signal acquisition circuit board 22 to drive the signal acquisition circuit board 22 to produce a slight displacement.

[0048] The rigid support body 212 is arranged at the outer periphery of the flexible deformation body 211, and the rigid support body 212 is used to fix the boundary of the flexible deformation body 211.

[0049] Optionally, continuing to refer to Figure 3 The rigid support body 212 is arranged at the outer periphery of the flexible deformation body 211, that is, the rigid support body 212 is located Figure 3 outside the middle red line. The rigid support body 212 has a relatively thick structure and is not easy to deform under force. The rigid support body 212 surrounds the outer periphery of the flexible deformation body 211 and serves as an external frame of the flexible deformation body 211. The rigid support body 212 mechanically fixes the boundary of the flexible deformation body 211, so that the force transmitted by the force receiving assembly 10 cannot be discharged through the boundary of the flexible deformation body 211, and the external force is fully converted into the deformation of the flexible deformation body 211.

[0050] The flexible deformation body 211 is used to produce deformation under the action of force and drive the signal acquisition circuit board 22 to produce displacement.

[0051] Optionally, the flexible deformation body 211 produces slight deformation under the action of the force transmitted by the force receiving assembly 10. The slight deformation of the flexible deformation body 211 drives the signal acquisition circuit board 22 to produce a slight displacement corresponding to the deformation.

[0052] In the embodiment, the elastic component includes a flexible deformation body and a rigid support body. The flexible deformation body is detachably connected with the signal acquisition circuit board and the force receiving assembly respectively. The rigid support body is arranged at the outer periphery of the flexible deformation body. The rigid support body is not easy to deform when subjected to force. The rigid support body surrounds the outer periphery of the flexible deformation body, fixes the boundary of the flexible deformation body, and ensures that the force transmitted by the force receiving assembly is not discharged through the boundary of the flexible deformation body, so that the external force is fully converted into the deformation of the flexible deformation body. The flexible deformation body is slightly deformed under the action of the force transmitted by the force receiving assembly. The slight deformation of the flexible deformation body drives the signal acquisition circuit board to produce a slight displacement corresponding to the deformation. The force transmitted by the force receiving assembly is fully converted into the deformation of the flexible deformation body, and the signal acquisition circuit board is driven to produce a corresponding displacement, thereby improving the precision of the signal acquisition circuit board in collecting the capacitance value change of each sensing capacitor, and further improving the accuracy of the square wave signal corresponding to each sensing capacitor, and finally improving the calculation precision of the six-dimensional force components.

[0053] Figure 3 Structure diagram of the capacitive six-dimensional force sensor provided by the embodiment of the application Figure 1 As shown in Figure 3 , the flexible deformation body 211 is detachably connected with the force receiving assembly 10 through a plurality of bolts.

[0054] Optionally, referring to Figure 3 , the flexible deformation body 211 includes a plurality of bolt holes, as indicated by the green arrows in Figure 4 , the flexible deformation body 211 includes four bolt holes. Figure 4 The force receiving assembly 10 also includes four bolt holes inside, and the flexible deformation body 211 is detachably connected with the force receiving assembly 10 through the four bolts to receive the force transmitted by the force receiving assembly 10 and produce deformation.

[0055] The flexible deformation body 211 is detachably connected with the signal acquisition circuit board 22 through a plurality of screws.

[0056] Optionally, continuing to refer to Figure 4 , the flexible deformation body 211 also includes a plurality of screw holes, as indicated by the red arrows in Figure 4 , the flexible deformation body 211 includes four screw holes. Figure 5 Structure diagram of the capacitive six-dimensional force sensor provided by the embodiment of the application Figure 5 As shown in Figure 5 , the signal acquisition circuit board 22 also includes four screw holes, and the flexible deformation body 211 is detachably connected with the signal acquisition circuit board 22 through the four screws to drive the signal acquisition circuit board 22 to produce displacement when the flexible deformation body 211 produces deformation.

[0057] In this embodiment, the flexible deformation body is detachably connected with the force receiving assembly through a plurality of bolts to receive the force transmitted by the force receiving assembly and generate deformation. The flexible deformation body is detachably connected with the signal acquisition circuit board through a plurality of screws to drive the signal acquisition circuit board to generate displacement when the flexible deformation body generates deformation. The accuracy of force transmission and the controllability of deformation are ensured.

[0058] As an optional implementation, the signal acquisition circuit board 22 includes a plurality of first acquisition circuits 221.

[0059] Optionally, referring to Figure 5 , the signal acquisition circuit board 22 includes a plurality of first acquisition circuits 221, for example, the signal acquisition circuit board 22 includes 8 first acquisition circuits 221, and each first acquisition circuit 221 corresponds to an independent sensing capacitor.

[0060] Each first acquisition circuit 221 is configured to acquire the capacitance change amount of each sensing capacitor when the signal acquisition circuit board 22 generates displacement, and output a square wave signal corresponding to each sensing capacitor according to the capacitance change amount of each sensing capacitor.

[0061] Optionally, each first acquisition circuit 221 accurately acquires the capacitance change amount of the corresponding single sensing capacitor when the signal acquisition circuit board 22 generates displacement, avoiding the superimposed interference of multi-capacitor signals.

[0062] Each first acquisition circuit 221 outputs a square wave signal corresponding to each sensing capacitor based on the acquired capacitance change amount of each sensing capacitor, so as to form a direct mapping of the capacitance change amount of the sensing capacitor, the frequency change of the square wave signal, and the six-dimensional component of the force.

[0063] In this embodiment, the signal acquisition circuit board includes a plurality of first acquisition circuits, and each first acquisition circuit corresponds to an independent sensing capacitor. Each first acquisition circuit accurately acquires the capacitance change amount of the corresponding single sensing capacitor when the signal acquisition circuit board generates displacement, avoiding the superimposed interference of multi-capacitor signals. And based on the acquired capacitance change amount of each sensing capacitor, a square wave signal corresponding to each sensing capacitor is outputted, so as to form a direct mapping of the capacitance change amount of the sensing capacitor, the frequency change of the square wave signal, and the six-dimensional component of the force. The anti-interference and reliability of the capacitive six-dimensional force sensor are improved.

[0064] As an optional implementation, the signal acquisition circuit board 22 further includes a second acquisition circuit 222 and a circuit board bridge 223, and the circuit board bridge 223 includes a reference capacitor.

[0065] Optionally, continuing to refer to Figure 5The circuit board bridge 223 is a fixed structure on the signal acquisition circuit board 22 and does not displace with the deformation of the flexible deformation body 211. The reference capacitor integrated on the circuit board bridge 223 is a stable capacitor that is not affected by external force. The capacitance change of the reference capacitor is caused only by environmental interference (such as temperature) or circuit aging, and is irrelevant to external force. The second acquisition circuit 222 on the signal acquisition circuit board 22 corresponds to the reference capacitor.

[0066] The second acquisition circuit 222 is configured to acquire the capacitance of the reference capacitor and output a reference square wave signal corresponding to the reference capacitor according to the capacitance of the reference capacitor. The reference square wave signal is used for temperature compensation and / or reference point compensation.

[0067] Optionally, the second acquisition circuit 222 acquires the capacitance of the reference capacitor and outputs a reference square wave signal corresponding to the reference capacitor according to the capacitance of the reference capacitor, where the frequency of the reference square wave signal only reflects temperature interference or circuit offset and is not affected by external force.

[0068] The temperature compensation and / or reference point compensation can be performed based on the reference square wave signal, the interference of environmental temperature and / or reference point drift on the capacitance measurement is eliminated, and the capacitance measurement accuracy of the signal acquisition circuit board 22 is improved.

[0069] In this embodiment, the signal acquisition circuit board further includes a second acquisition circuit and a circuit board bridge. The circuit board bridge includes a reference capacitor. The circuit board bridge is a fixed structure on the signal acquisition circuit board and does not displace with the deformation of the flexible deformation body. The reference capacitor integrated on the circuit board bridge is a stable capacitor that is not affected by external force. The capacitance change of the reference capacitor is caused only by environmental interference or circuit aging. The second acquisition circuit acquires the capacitance of the reference capacitor and outputs a reference square wave signal corresponding to the reference capacitor according to the capacitance of the reference capacitor. The frequency of the reference square wave signal only reflects temperature interference or circuit offset and is not affected by external force. The temperature compensation and / or reference point compensation can be performed based on the reference square wave signal, the interference of environmental temperature and / or reference point drift on the capacitance measurement is eliminated, and the capacitance measurement accuracy of the signal acquisition circuit board is improved.

[0070] Figure 6 Structure diagram of the capacitive six-dimensional force sensor provided in the embodiments of the present application Figure 6 As shown in Figure 6 , the elastic component 21 further includes a plurality of elastic body protrusions 213.

[0071] Optionally, referring to Figure 6 , the elastic component 21 further includes a plurality of elastic body protrusions 213, for example, Figure 6 , the elastic component 21 includes three elastic body protrusions 213.

[0072] When the elastic component 21 is detachably connected with the signal acquisition circuit board 22, each elastic body protrusion 213 is located outside the periphery of the circuit board bridge 223. Each elastic body protrusion 213 is used to shield electromagnetic interference for the circuit board bridge 223.

[0073] Optionally, the capacitance is extremely sensitive to external electromagnetic field. The external electromagnetic field can generate additional induced charge between the plates of the reference capacitor, causing the actual capacitance to deviate from the design value, resulting in capacitance drift. The capacitance drift can directly cause the frequency distortion of the reference square wave signal output by the second acquisition circuit 222, affecting the compensation effect.

[0074] Continuing to refer to Figure 7 , when the elastic component 21 is detachably connected with the signal acquisition circuit board 22, each elastic body protrusion 213 is located outside the periphery of the circuit board bridge 223. Each elastic body protrusion 213 can avoid electromagnetic interference from the edge or gap of the circuit board bridge 223, shield electromagnetic interference for the circuit board bridge 223, prevent capacitance drift, and ensure the compensation effect.

[0075] In this embodiment, the elastic component further includes a plurality of elastic body protrusions. When the elastic component is detachably connected with the signal acquisition circuit board, each elastic body protrusion is located outside the periphery of the circuit board bridge. Each elastic body protrusion can avoid electromagnetic interference from the edge or gap of the circuit board bridge, shield electromagnetic interference for the circuit board bridge, prevent capacitance drift, and ensure the compensation effect.

[0076] Figure 7 Structure diagram of the capacitive six-dimensional force sensor provided in the embodiment Figure 7 As shown in Figure 7 , the rigid support body 212 includes a plurality of first vertical capacitor plates 2121 and a plurality of first flat capacitor plates 2122 arranged adjacent to each first vertical capacitor plate 2121.

[0077] Optionally, referring to Figure 8 , the rigid support body 212 includes a plurality of first vertical capacitor plates 2121, for example, the four first vertical capacitor plates 2121 indicated by the yellow lines in Figure 8 . The rigid support body 212 further includes a plurality of first flat capacitor plates 2122, for example, the four first flat capacitor plates 2122 indicated by the green lines in Figure 8 . The first vertical capacitor plates 2121 and the first flat capacitor plates 2122 are arranged adjacent to each other in one-to-one correspondence.

[0078] Among them, each first vertical capacitor plate 2121 and each first flat capacitor plate 2122 are fixed in the rigid support body 212 and are stable in position and will not deform themselves under external force, serving as fixed capacitor plate levels in each sensing capacitor.

[0079] In the embodiment, the rigid support body comprises a plurality of first vertical capacitor plates and a plurality of first flat capacitor plates arranged adjacent to each first vertical capacitor plate. Each first vertical capacitor plate and each first flat capacitor plate are fixed in the rigid support body, are stable in position, and do not deform under external force, and serve as fixed capacitor plate levels in each sensing capacitor.

[0080] Figure 9 Structure diagram of the capacitive six-dimensional force sensor provided in the embodiment Figure 9 As shown in Figure 9 , the signal acquisition circuit board 22 further comprises a plurality of second vertical capacitor plates 224 and a plurality of second flat capacitor plates 225 arranged adjacent to each second vertical capacitor plate 224.

[0081] Optionally, referring to Figure 9 , the signal acquisition circuit board 22 further comprises a plurality of second vertical capacitor plates 224, for example, the four second vertical capacitor plates 224 indicated by the yellow lines in Figure 9 . The signal acquisition circuit board 22 further comprises a plurality of second flat capacitor plates 225, for example, the four second flat capacitor plates 225 indicated by the green lines in Figure 10 . Each second vertical capacitor plate 224 is arranged adjacent to a corresponding second vertical capacitor plate 224.

[0082] Each second vertical capacitor plate 224 and each second flat capacitor plate 225 will synchronously displace with the displacement of the signal acquisition circuit board 22, and serve as movable capacitor plate levels in each sensing capacitor.

[0083] In the embodiment, the signal acquisition circuit board further comprises a plurality of second vertical capacitor plates and a plurality of second flat capacitor plates arranged adjacent to each second vertical capacitor plate, each second vertical capacitor plate and each second flat capacitor plate will synchronously displace with the displacement of the signal acquisition circuit board, and serve as movable capacitor plate levels in each sensing capacitor.

[0084] Figure 11 Structure diagram of the capacitive six-dimensional force sensor provided in the embodiment Figure 12 As shown in Figure 13 , the first vertical capacitor plate 2121 and the second vertical capacitor plate 224 form a first sensing capacitor.

[0085] Optionally, referring to Figure 10 , when the elastic component 21 is detachably connected to the signal acquisition circuit board 22, the first vertical capacitor plate 2121 serves as a fixed capacitor plate level, and the second vertical capacitor plate 224 serves as a movable capacitor plate level to form a first sensing capacitor. Exemplarily, the four first vertical capacitor plates 2121 and the four second vertical capacitor plates 224 form four first sensing capacitors, respectively.

[0086] Specifically, when the elastic component 21 causes the signal acquisition circuit board 22 to move, the position of the first vertical capacitor plate 2121 in the rigid support 212 remains fixed, while the second vertical capacitor plate 224 on the signal acquisition circuit board 22 moves synchronously with the movement of the signal acquisition circuit board 22. At this time, the distance between the first vertical capacitor plate 2121 and the second vertical capacitor plate 224 changes, causing the capacitance of the first induced capacitor formed by the first vertical capacitor plate 2121 and the second vertical capacitor plate 224 to change, thereby causing the frequency of the square wave signal corresponding to the output first induced capacitor to change.

[0087] In this embodiment, when the elastic component and the signal acquisition circuit board are detachably connected, the first vertical capacitor plate, as a fixed capacitor plate, and the second vertical capacitor plate, as a movable capacitor plate, form a first sensing capacitor to accurately acquire the change in capacitance of the first sensing capacitor under the action of external force, and then output the square wave signal corresponding to the first sensing capacitor.

[0088] Figure 1 A schematic diagram of the structure of the capacitive six-dimensional force sensor provided in the embodiments of this application. Figure 10 ,like Figure 10 As shown, the first flat capacitor plate 2122 and the second flat capacitor plate 225 form the second inductive capacitor.

[0089] Optionally, refer to Figure 11 When the elastic component 21 is detachably connected to the signal acquisition circuit board 22, Figure 2 The first flat capacitor plate 2122 shown in (a) serves as a fixed capacitor plate stage, and... Figure 11 The movable capacitor plate stage 225 of the second flat capacitor plate shown in (b) forms a second inductive capacitor. For example, the four first flat capacitor plates 2122 and the four second flat capacitor plates 225 respectively form four second inductive capacitors.

[0090] Specifically, when the elastic component 21 causes the signal acquisition circuit board 22 to move, the position of the first flat capacitor plate 2122 in the rigid support 212 remains fixed, while the second flat capacitor plate 225 on the signal acquisition circuit board 22 moves synchronously with the movement of the signal acquisition circuit board 22. At this time, the distance between the first flat capacitor plate 2122 and the second flat capacitor plate 225 changes, causing the capacitance of the second induced capacitor formed by the first flat capacitor plate 2122 and the second flat capacitor plate 225 to change, thereby causing the frequency of the square wave signal corresponding to the output second induced capacitor to change.

[0091] In this embodiment, when the elastic component and the signal acquisition circuit board are detachably connected, the first flat capacitor plate, as a fixed capacitor plate, and the second flat capacitor plate, as a movable capacitor plate, form a second sensing capacitor to accurately acquire the capacitance change of the second sensing capacitor under the action of external force, and then output the square wave signal corresponding to the second sensing capacitor.

[0092] Combination Figure 10 , Figure 12 , Figure 12 and Figure 12 The circuit structure of the first acquisition circuit 221 in the signal acquisition circuit board 22 of this application embodiment will be explained in detail.

[0093] Figure 12 Schematic diagram of the structure of the first acquisition circuit provided in the embodiments of this application Figure 13 ,like Figure 3 As shown, with Figure 13 Taking a variable capacitor Cx as an example, the first comparator U1 is an operational amplifier that outputs a square wave signal corresponding to the variable capacitor Cx based on the capacitance change of Cx. The width of this square wave signal varies with the capacitance of Cx. The second comparator U2 is a Schmitt trigger that shapes the square wave signal corresponding to the variable capacitor Cx, ultimately outputting a shaped square wave signal, which is the square wave signal corresponding to the first sensing capacitor.

[0094] Specifically, Figure 13 Schematic diagram of the structure of the first acquisition circuit provided in the embodiments of this application Figure 10 ,like ​ As shown, the non-inverting input of the first comparator U1 is connected to a reference voltage Vref, where the reference voltage Vref is... ​ The third resistor R3 and the fourth resistor R4 form a resistor divider circuit, providing a stable reference voltage Vref to the first comparator U1 through the third resistor R3 and the fourth resistor R4. The inverting input terminal of the first comparator U1 is connected to one end of the variable resistor Cx and one end of the first resistor R1, respectively, and the other end of the variable resistor Cx is grounded. The other end of the first resistor R1 is connected to the output terminal of the first comparator U1. One end of the second resistor R2 is connected to the non-inverting input terminal of the first comparator U1, and the other end is connected to the output terminal of the first comparator U1.

[0095] According to the comparator principle, when the voltage V1+ connected to the non-inverting input terminal of the first comparator U1 is greater than the voltage V1- connected to the inverting input terminal of the first comparator U1, the output signal Uo1 of the first comparator U1 approaches VCC. At this time, the variable capacitor Cx is charged through the first resistor R1. Based on the RC charging curve, the voltage V1- connected to the inverting input terminal of the first comparator U1 will increase as the variable capacitor Cx charges, i.e. , where t1 is the charging time of the variable capacitor Cx.

[0096] As the voltage V1- connected to the inverting input of the first comparator U1 gradually increases, when the voltage V1+ connected to the non-inverting input of the first comparator U1 is less than the voltage V1- connected to the inverting input, the level of the signal Uo1 output from the first comparator U1 flips and approaches GND. At this time, the variable capacitor Cx is discharged to GND through the first resistor R1. Based on the RC discharge curve, the voltage V1- connected to the inverting input of the first comparator U1 will decrease as the variable capacitor Cx discharges. Where t2 is the discharge duration of the variable capacitor Cx. As the voltage V1- connected to the inverting input terminal of the first comparator U1 gradually decreases, when the voltage V1+ connected to the non-inverting input terminal of the first comparator U1 is greater than the voltage V1- connected to the inverting input terminal of the first comparator U1, the level of the signal Uo1 output by the output terminal of the first comparator U1 flips again and approaches VCC.

[0097] ​ This is a waveform diagram illustrating the square wave signal and the charging / discharging time of the variable capacitor provided in an embodiment of this application, as shown below. ​ As shown, the output signal Uo1 of the first comparator U1 is a square wave signal, where the high-level duration of the square wave signal is the duration for which Cx is charged to VCC, i.e. ​ In the duration t1, the low-level duration of the square wave signal is the duration of Cx discharging to GND, i.e. ​ The duration t2 is as follows. Since the capacitance value of the variable capacitor Cx is variable when the capacitive six-dimensional force sensor is subjected to force, the width of the square wave signal generated changes with the capacitance value of the variable capacitor Cx. When the capacitance value of the variable capacitor Cx increases, the width of the square wave signal becomes longer and the frequency becomes lower; when the capacitance value of the variable capacitor Cx decreases, the width of the square wave signal becomes shorter and the frequency becomes higher.

[0098] ​ Schematic diagram of the structure of the first acquisition circuit provided in the embodiments of this application ​ ,like ​As shown, the variable capacitance Cx corresponding square wave signal outputted by the first comparator U1 is shaped by the second comparator U2, and an ideal square wave signal is outputted, wherein the frequency of the square wave signal outputted by the second comparator U2 is consistent with the frequency of the variable capacitance Cx corresponding square wave signal outputted by the first comparator U1.

[0099] Specifically, referring to ​ , the in-phase input end of the second comparator U2 is connected to the reference voltage Vref, and the anti-phase input end of the second comparator U2 is connected to the variable capacitance Cx corresponding square wave signal Uo1 outputted by the first comparator U1, and the second comparator U2 can shape the square wave signal Uo1 as an ideal square wave signal Uo2 as the first sensing capacitance corresponding square wave signal, wherein, ​ The fifth resistor R5 shown is used for current limiting protection of the second comparator U2.

[0100] Correspondingly, the process of obtaining the second sensing capacitance corresponding square wave signal is similar to that of obtaining the first sensing capacitance corresponding square wave signal, and will not be described here. Based on the frequency of each first sensing capacitance corresponding square wave signal and the frequency of each second sensing capacitance corresponding square wave signal, the force is calculated, and the collection accuracy of the capacitive six-dimensional force sensor is improved.

[0101] The above is only a specific embodiment of the present application, but the protection scope of the present application is not limited thereto, and any person skilled in the art can easily think of changes or replacements within the technical range disclosed by the present application, which shall be covered within the protection scope of the present application.

Claims

1. A capacitive six-axis force sensor, characterized by The application relates to a force sensing device. The force sensing device comprises a force receiving component and a sensing capacitor component. The sensing capacitor component is detachably connected with the force receiving component. The force receiving component is used for transmitting force to the sensing capacitor component when the force receiving component is subjected to force. The sensing capacitor component is used for outputting square wave signals under the action of force, wherein the frequency of the square wave signals has a linear matrix relationship with the six-dimensional components of the force.

2. The capacitive six-axis force sensor of claim 1, wherein, The sensing capacitor component comprises an elastic component and a signal acquisition circuit board. The elastic component is detachably connected with the force receiving component. The elastic component is detachably connected with the signal acquisition circuit board, and a plurality of sensing capacitors are formed between the elastic component and the signal acquisition circuit board. The elastic component is used for generating deformation under the action of force and driving the signal acquisition circuit board to generate displacement. The signal acquisition circuit board is used for collecting the capacitance variation of each sensing capacitor when the signal acquisition circuit board generates displacement, and outputting square wave signals corresponding to each sensing capacitor according to the capacitance variation of each sensing capacitor, wherein the frequency of the square wave signals is used for representing the size of the six-dimensional components of the force.

3. The capacitive six-axis force sensor of claim 2, wherein, The elastic component comprises a flexible deformation body and a rigid support body. The flexible deformation body is detachably connected with the signal acquisition circuit board and the force receiving component respectively. The rigid support body is arranged at the outer periphery of the flexible deformation body, and is used for fixing the boundary of the flexible deformation body. The flexible deformation body is used for generating deformation under the action of force and driving the signal acquisition circuit board to generate displacement.

4. The capacitive six-axis force sensor of claim 3, wherein, The flexible deformation body is detachably connected with the force receiving component through a plurality of bolts. The flexible deformation body is detachably connected with the signal acquisition circuit board through a plurality of screws.

5. The capacitive six-axis force sensor of claim 2, wherein, The signal acquisition circuit board comprises a plurality of first acquisition circuits. Each first acquisition circuit is used for collecting the capacitance variation of each sensing capacitor when the signal acquisition circuit board generates displacement, and outputting square wave signals corresponding to each sensing capacitor according to the capacitance variation of each sensing capacitor.

6. The capacitive six-axis force sensor of claim 5, wherein, The signal acquisition circuit board further comprises a second acquisition circuit and a circuit board bridge, and the circuit board bridge comprises a reference capacitor. The second acquisition circuit is used for collecting the capacitance of the reference capacitor, and outputting reference square wave signals corresponding to the reference capacitor according to the capacitance of the reference capacitor, wherein the reference square wave signals are used for temperature compensation and / or base point compensation.

7. The capacitive six-axis force sensor of claim 3, wherein, The elastic component further comprises a plurality of elastic body protrusions. When the elastic component is detachably connected with the signal acquisition circuit board, each elastic body protrusion is located at the outer periphery of the circuit board bridge. Each elastic body protrusion is used for shielding electromagnetic interference for the circuit board bridge.

8. The capacitive six-axis force sensor of claim 3, wherein, The rigid support body comprises a plurality of first vertical capacitor plates and a plurality of first flat capacitor plates arranged adjacent to each first vertical capacitor plate.

9. The capacitive six-axis force sensor of claim 6, wherein, The signal acquisition circuit board further comprises a plurality of second vertical capacitor plates and a plurality of second flat capacitor plates arranged adjacent to each second vertical capacitor plate.

10. The capacitive six-axis force sensor according to claim 8 or 9, characterized in that A first vertical capacitor plate and a second vertical capacitor plate form a first sensing capacitor. A first flat capacitor plate and a second flat capacitor plate form a second sensing capacitor.

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