Six-axis force sensor and manufacturing method thereof

Abstract

Embodiments of the present application disclose a six-axis force sensor and a manufacturing method thereof. The six-axis force sensor includes: a force-receiving block; a support frame that surrounds the force-receiving block, and there is a gap between the force-receiving block and the support frame; multiple sets of elastic members, which are arranged in the gap and are respectively connected to the force-receiving block and the support frame. The multiple sets of elastic members divide the gap into multiple first deformation cavities; several force-sensitive resistors are arranged in the elastic members to form six Wheatstone bridges, which are respectively used to measure the first force, the second force, the third force, the first torque, the second torque, and the third torque; each set of elastic members includes a pair of spaced elastic beams; any pair of elastic beams and the force-receiving block and the support frame enclose a second deformation cavity. According to the present application, its double-elastic-beam structure provides a deployable space for the force-sensitive resistors, realizes the self-decoupling between the measured force and torque and the unmeasured force and torque, and improves the accuracy of the six-axis force sensor of the present application.

Description

Technical Field

[0001] This application relates to the technical field of force sensors, and particularly relates to a six-axis force sensor and a manufacturing method thereof. Background Art

[0002] Existing six-axis force sensors usually adopt a pure mechanical structure design, with a large structural volume and being inconvenient for use in the micro field. General micro six-axis force sensors often have a complex structure, a large processing difficulty, and a complex decoupling between the forces of each axis.

[0003] For piezoresistive force sensors, piezoresistors often need to form a Wheatstone bridge to achieve precise measurement of force. A complete low-coupling six-axis force sensor requires six sets of Wheatstone bridges with a total of 24 piezoresistors. To ensure the sensitivity to the measured dimension force and the low response to the forces of other dimensions, there are special requirements for the arrangement positions of the piezoresistors. In a single-beam structure, the force distribution on the beam is fixed, and only one piezoresistor can be placed at the same position, resulting in the need for double-layer doping or double-sided doping of the beam to arrange the piezoresistors in layers. This leads to complex process processing, and it is difficult to ensure the consistency of the doping concentrations on the upper and lower surfaces, and the consistency of the devices is poor. Therefore, how to set the elastic beam structure to meet the arrangement of piezoresistors is an urgent problem to be solved at present. Summary of the Invention

[0004] Embodiments of this application provide a six-axis force sensor and a manufacturing method thereof, providing an arrangeable space for piezoresistors and for the self-decoupling between the measured force, moment or moment and non-measured force, moment.

[0005] To solve the above technical problems, embodiments of this application disclose the following technical solutions:

[0006] On the one hand, a six-axis force sensor is provided, including:

[0007] A force-receiving block;

[0008] A support frame, the support frame surrounds the force-receiving block, and there is a gap between the force-receiving block and the support frame;

[0009] Multiple sets of elastic members, multiple sets of the elastic members are arranged in the gap and are respectively connected to the force-receiving block and the support frame. Multiple sets of the elastic members divide the gap into multiple first deformation cavities, and the first deformation cavities are used to accommodate the deformation of the elastic members;

[0010] Several piezoresistors, the several piezoresistors are arranged in the elastic members to form six sets of Wheatstone bridges, which are respectively used to measure the first force, the second force, the third force, the first moment, the second moment, and the third moment;

[0011] Each set of the elastic members includes a pair of elastic beams arranged at intervals; any pair of the elastic beams, the force-receiving block and the support frame enclose a second deformation cavity for accommodating the deformation of the elastic beams.

[0012] In addition to one or more of the features disclosed above, or as an alternative, the six-axis force sensor has a first plane, in which a first axial direction and a second axial direction intersect and are perpendicular to each other. One side surface of the elastic member is in the first plane, and the elastic beams in the same set of the elastic members are symmetric about the first axial direction or the second axial direction.

[0013] In addition to one or more of the features disclosed above, or as an alternative, the plurality of force-sensitive resistors are all arranged in the first plane;

[0014] In the first plane, there is a central point. The force-sensitive resistors in the Wheatstone bridge for measuring the first force, the second force or the third force are rotationally symmetric about the central point in the first plane;

[0015] The force-sensitive resistors in the Wheatstone bridge for measuring the first torque, the second torque and the third torque are symmetric about the first axial direction or the second axial direction in the first plane.

[0016] In addition to one or more of the features disclosed above, or as an alternative, the Wheatstone bridges for measuring the first force, the second force, the third force, the first torque, the second torque and the third torque are all full-arm Wheatstone bridges.

[0017] In addition to one or more of the features disclosed above, or as an alternative, the direction of the first force extends along the first axial direction. The plurality of force-sensitive resistors include a first force-sensitive resistor, a second force-sensitive resistor, a third force-sensitive resistor and a fourth force-sensitive resistor for measuring the first force. The first force-sensitive resistor and the second force-sensitive resistor are respectively arranged on a pair of the elastic beams on one side of the force-receiving block with respect to the second axial direction, and the third force-sensitive resistor and the fourth force-sensitive resistor are respectively arranged on a pair of the elastic beams on the other side; the first force-sensitive resistor and the second force-sensitive resistor are diagonally arranged in the bridge, and the third force-sensitive resistor and the fourth force-sensitive resistor are diagonally arranged in the bridge;

[0018] The direction of the second force extends along the second axial direction. The plurality of force-sensitive resistors further includes a fifth force-sensitive resistor, a sixth force-sensitive resistor, a seventh force-sensitive resistor, and an eighth force-sensitive resistor for measuring the second force. The fifth force-sensitive resistor and the eighth force-sensitive resistor are respectively disposed on a pair of the elastic beams on one side of the force-receiving block with respect to the first axial direction, and the sixth force-sensitive resistor and the seventh force-sensitive resistor are respectively disposed on a pair of the elastic beams on the other side. The fifth force-sensitive resistor and the eighth force-sensitive resistor are diagonally disposed in the bridge, and the sixth force-sensitive resistor and the seventh force-sensitive resistor are diagonally disposed in the bridge. The direction of the third force extends along the third axial direction. The plurality of force-sensitive resistors further includes a ninth force-sensitive resistor, a tenth force-sensitive resistor, an eleventh force-sensitive resistor, and a twelfth force-sensitive resistor for measuring the third force. The fifth force-sensitive resistor and the tenth force-sensitive resistor are disposed on one of the elastic beams on one side of the force-receiving block with respect to the first axial direction or the second axial direction, and the eleventh force-sensitive resistor and the twelfth force-sensitive resistor are both disposed on one of the elastic beams on the other side. The ninth force-sensitive resistor and the twelfth force-sensitive resistor are diagonally disposed in the bridge, and the tenth force-sensitive resistor and the eleventh force-sensitive resistor are diagonally disposed in the bridge.

[0019] In addition to one or more of the features disclosed above, or as an alternative, the direction of the first torque rotates counterclockwise about the first axial direction. The plurality of force-sensitive resistors includes a thirteenth force-sensitive resistor, a fourteenth force-sensitive resistor, a fifteenth force-sensitive resistor, and a sixteenth force-sensitive resistor for measuring the first torque. The thirteenth force-sensitive resistor and the fourteenth force-sensitive resistor are disposed on one of the elastic beams on one side with respect to the first axial direction, and the fifteenth force-sensitive resistor and the sixteenth force-sensitive resistor are disposed on one of the elastic beams on the other side. The thirteenth force-sensitive resistor and the fifteenth force-sensitive resistor are diagonally disposed in the bridge, and the fourteenth force-sensitive resistor and the sixteenth force-sensitive resistor are diagonally disposed in the bridge.

[0020] The direction of the second torque rotates counterclockwise about the second axial direction. The plurality of force-sensitive resistors further includes a seventeenth force-sensitive resistor, an eighteenth force-sensitive resistor, a nineteenth force-sensitive resistor, and a twentieth force-sensitive resistor for measuring the second torque. The seventeenth force-sensitive resistor and the eighteenth force-sensitive resistor are disposed on one of the elastic beams on one side with respect to the second axial direction, and the nineteenth force-sensitive resistor and the twentieth force-sensitive resistor are disposed on one of the elastic beams on the other side. The seventeenth force-sensitive resistor and the nineteenth force-sensitive resistor are diagonally disposed in the bridge, and the eighteenth force-sensitive resistor and the twentieth force-sensitive resistor are diagonally disposed in the bridge.

[0021] The direction of the third moment rotates counterclockwise around the third axis. The plurality of force-sensitive resistors include the twenty-first force-sensitive resistor, the twenty-second force-sensitive resistor, the twenty-third force-sensitive resistor, and the twenty-fourth force-sensitive resistor for measuring the third moment. The twenty-first force-sensitive resistor and the twenty-fourth force-sensitive resistor are respectively disposed on a pair of the elastic beams on one side with respect to the first axis or the second axis, and the twenty-second force-sensitive resistor and the twenty-third force-sensitive resistor are respectively disposed on a pair of the elastic beams on the other side; the twenty-first force-sensitive resistor and the twenty-third force-sensitive resistor are disposed diagonally in the bridge, and the twenty-second force-sensitive resistor and the twenty-fourth force-sensitive resistor are disposed diagonally in the bridge.

[0022] In addition to one or more of the above-disclosed features, or as an alternative, the eleventh force-sensitive resistor and the nineteenth force-sensitive resistor are the same force-sensitive resistor, and the twelfth force-sensitive resistor and the twentieth force-sensitive resistor are the same force-sensitive resistor.

[0023] In addition to one or more of the above-disclosed features, or as an alternative, the force-sensitive resistors for measuring the first force and the second force are disposed at a position of 1 / 6 to 1 / 2 of the elastic beam close to the support frame.

[0024] In addition to one or more of the above-disclosed features, or as an alternative, the force-sensitive resistors for measuring the third force, the first moment, and the second moment are disposed at one end close to the force-receiving block and one end close to the support frame.

[0025] In addition to one or more of the above-disclosed features, or as an alternative, the force-sensitive resistors for measuring the third moment are all disposed at one end of the elastic beam close to the force-receiving block, or the force-sensitive resistors for measuring the third moment are all disposed at one end of the elastic beam close to the support frame;

[0026] The force-sensitive resistors for measuring the third moment are disposed on the outer side of one elastic beam away from the other elastic beam in the same group of elastic members.

[0027] In addition to one or more of the above-disclosed features, or as an alternative, the six-axis force sensor further has a third axis that intersects and is perpendicular to the first plane. In the third axis direction, the thickness of the support frame is greater than the thicknesses of the force-receiving block and the elastic members.

[0028] On the other hand, a method for manufacturing a six-axis force sensor is further disclosed. In addition to one or more of the above-disclosed features, or as an alternative, the method for manufacturing a six-axis force sensor includes the six-axis force sensor as described in any one of the above, and the method for manufacturing a six-axis force sensor includes:

[0029] Provide a silicon wafer, and form an oxide layer on one side surface of the silicon wafer;

[0030] Perform patterning on the oxide layer to form a force-sensitive resistor pattern, and dope the silicon wafer at the position of the force-sensitive resistor pattern to form a force-sensitive resistor in the silicon wafer;

[0031] Perform patterning on the oxide layer to form an ohmic contact layer pattern, and dope the silicon wafer at the position of the ohmic contact layer pattern to form an ohmic contact layer on the surface layer of the silicon wafer, and the ohmic contact layer connects the force-sensitive resistor; etch the ohmic contact layer to form a plurality of ohmic contact areas corresponding to the force-sensitive resistors one by one; anneal to activate the force-sensitive resistor and the ohmic contact areas;

[0032] Form a trace on one side surface of the silicon wafer having the ohmic contact areas, and the trace connects the force-sensitive resistor through the ohmic contact areas;

[0033] Perform patterning and etching on the side surface of the silicon wafer facing away from the trace to form a support frame to the thickness positions of the force-receiving block and the elastic member;

[0034] Perform patterning and etching on the area other than the support frame on the side surface of the silicon wafer facing away from the trace to form the force-receiving block and the elastic member.

[0035] One of the above technical solutions has the following advantages or beneficial effects: The elastic member in this application adopts a double elastic beam structure. Compared with the single elastic beam structure in the prior art, the double elastic beam structure provides more layout space for the force-sensitive resistor; the larger layout space can increase the distance between adjacent force-sensitive resistors, reduce the production process difficulty and manufacturing cost, and at the same time avoid signal errors caused by the Wheatstone bridge being affected by non-measured forces and torques, realizing the self-decoupling between the measured forces and torques and the non-measured forces and torques, and improving the accuracy of the six-axis force sensor in this application. A number of force-sensitive resistors are arranged on the elastic beam to form six groups of Wheatstone bridges respectively for measuring six-axis forces and torques. The force-sensitive resistors are all arranged in the same plane of the elastic beam. Compared with the technical solution in the prior art where the force-sensitive resistors are arranged in different planes, this application greatly reduces the manufacturing process difficulty and manufacturing cost, and doping to manufacture the force-sensitive resistors in the same plane can ensure consistent doping concentration, greatly improving the consistency of all force-sensitive resistor devices, and further improving the measurement accuracy of the six-axis force sensor in this application. Description of the Drawings

[0036] The following will combine the drawings and describe the specific implementation manners of this application in detail, and the technical solutions and other beneficial effects of this application will be obvious.

[0037] Figure 1It is a schematic structural diagram of a six-axis force sensor provided according to an embodiment of the present application.

[0038] Figure 2 It is a schematic diagram of the force direction of a six-axis force sensor provided according to an embodiment of the present application.

[0039] Figure 3 It is a schematic diagram of the torque direction of a six-axis force sensor provided according to an embodiment of the present application.

[0040] Figure 4 It shows a schematic diagram of the stress distribution of a six-axis force sensor proposed according to an embodiment of the present application under the action of a first force, a second force, a third force, a first torque, a second torque, and a third torque respectively.

[0041] Figure 5 It is a schematic diagram of the distribution of force-sensitive resistors in a Wheatstone bridge for measuring the first force in a six-axis force sensor provided according to an embodiment of the present application.

[0042] Figure 6 It is a schematic circuit diagram of a Wheatstone bridge for measuring the first force in a six-axis force sensor provided according to an embodiment of the present application.

[0043] Figure 7 It is a schematic diagram of the distribution of force-sensitive resistors in a Wheatstone bridge for measuring the second force in a six-axis force sensor provided according to an embodiment of the present application.

[0044] Figure 8 It is a schematic circuit diagram of a Wheatstone bridge for measuring the second force in a six-axis force sensor provided according to an embodiment of the present application.

[0045] Figure 9 It is a schematic diagram of the distribution of force-sensitive resistors in a Wheatstone bridge for measuring the third force in a six-axis force sensor provided according to an embodiment of the present application.

[0046] Figure 10 It is a schematic circuit diagram of a Wheatstone bridge for measuring the third force in a six-axis force sensor provided according to an embodiment of the present application.

[0047] Figure 11 It is a schematic diagram of the distribution of force-sensitive resistors in a Wheatstone bridge for measuring the first torque in a six-axis force sensor provided according to an embodiment of the present application.

[0048] Figure 12 It is a schematic circuit diagram of a Wheatstone bridge for measuring the first torque in a six-axis force sensor provided according to an embodiment of the present application.

[0049] Figure 13It is a schematic diagram of the distribution of force-sensitive resistors in a Wheatstone bridge for measuring the second moment in a six-axis force sensor provided by an embodiment of the present application.

[0050] Figure 14 It is a schematic circuit diagram of a Wheatstone bridge for measuring the second moment in a six-axis force sensor provided by an embodiment of the present application.

[0051] Figure 15 It is a schematic diagram of the distribution of force-sensitive resistors in a Wheatstone bridge for measuring the third moment in a six-axis force sensor provided by an embodiment of the present application.

[0052] Figure 16 It is a schematic circuit diagram of a Wheatstone bridge for measuring the third moment in a six-axis force sensor provided by an embodiment of the present application.

[0053] In the figure: 100 - support frame; 200 - force-receiving block; 300 - elastic member; 311 - first elastic beam; 312 - second elastic beam; 321 - third elastic beam; 322 - fourth elastic beam; 331 - fifth elastic beam; 332 - sixth elastic beam; 341 - seventh elastic beam; 342 - eighth elastic beam; 400 - gap; 401 - first deformation cavity; 402 - second deformation cavity. Detailed implementation manners

[0054] In order to make the objectives, technical solutions, and beneficial effects of the present application clearer and more understandable, the present application will be further described in detail below with reference to the accompanying drawings and specific implementation manners. It should be understood that the specific implementation manners described in this specification are only for explaining the present application and not for limiting the present application.

[0055] In the description of the present application, it should be understood that the terms "center", "longitudinal", "transverse", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "clockwise", "counterclockwise", etc. indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for facilitating the description of the present application and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation. Therefore, it should not be construed as a limitation to the present application. In addition, the terms "first" and "second" are only used for descriptive purposes and cannot be understood as indicating or implying relative importance or implicitly specifying the quantity of the indicated technical features. Thus, the features defined with "first" and "second" may explicitly or implicitly include one or more of the said features. In the description of the present application, "a plurality" means two or more, unless otherwise specifically defined.

[0056] In the description of the present application, it should be noted that unless otherwise clearly defined and limited, the terms "installed", "connected", and "coupled" should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection, a direct connection, or an indirect connection through an intermediate medium. It can be the communication inside two components or the interaction relationship between two components. For those of ordinary skill in the art, the specific meanings of the above terms in the present application can be understood according to specific circumstances.

[0057] In the present application, unless otherwise clearly defined and limited, the first feature being "above" or "below" the second feature may include the direct contact between the first and second features, or may include the situation where the first and second features are not in direct contact but in contact through other features therebetween. Moreover, the first feature being "above", "over", and "on top of" the second feature includes that the first feature is directly above and obliquely above the second feature, or merely indicates that the horizontal height of the first feature is higher than that of the second feature. The first feature being "below", "beneath", and "underneath" the second feature includes that the first feature is directly below and obliquely below the second feature, or merely indicates that the horizontal height of the first feature is lower than that of the second feature.

[0058] Referring to Figure 1 , Figure 1 , which shows a schematic structural diagram of a six-axis force sensor provided according to an embodiment of the present application. The six-axis force sensor provided by an embodiment of the present application includes: a force-receiving block 200, a support frame 100, multiple groups of elastic members 300, and several force-sensitive resistors. The support frame 100 surrounds the force-receiving block 200, and there is a gap 400 between the force-receiving block 200 and the support frame 100; multiple groups of elastic members 300 are disposed in the gap and are respectively connected to the force-receiving block 200 and the support frame 100. The multiple groups of elastic members 300 divide the gap 400 into multiple first deformation cavities 401, and the first deformation cavities 401 are used to accommodate the deformation of the elastic members 300; several force-sensitive resistors are arranged in the elastic members 300 to form six groups of Wheatstone bridges, which are respectively used to measure the first force, the second force, the third force, the first torque, the second torque, and the third torque.

[0059] Furthermore, each group of elastic members 300 includes a pair of spaced-apart elastic beams; any pair of elastic beams and the force-receiving block 200 and the support frame 100 enclose a second deformation cavity 402, and the second deformation cavity 402 is used to accommodate the deformation of the elastic beams. The double-elastic-beam structure provides a deployable space for the force-sensitive resistors, realizes the self-decoupling between the measured forces and torques and the non-measured forces and torques, and improves the accuracy of the six-axis force sensor of the present application.

[0060] Specifically, the force-receiving block 200 is a square block structure, and the force-receiving block 200 is arranged at the geometric center position of the support frame 100, and the geometric center of the force-receiving block 200 coincides with the geometric center of the support frame 100. The square sides of the force-receiving block 200 are arranged parallel to the square sides of the support frame 100, and the distance from any square side of the force-receiving block 200 to the corresponding square side of the support frame 100 is equal.

[0061] Further, the six-axis force sensor has a first plane, in which a first axial direction X and a second axial direction Y that intersect and are perpendicular are provided. One side surface of the elastic member 300 is in the first plane, and a pair of elastic beams in the same group of elastic members 300 are symmetric about the first axial direction X or the second axial direction Y.

[0062] Specifically, the elastic beams include a first elastic beam 311 and a second elastic beam 312 provided on one side of the force-receiving block 200 with respect to the first axial direction X, a fifth elastic beam 331 and a sixth elastic beam 332 on the other side, a third elastic beam 321 and a fourth elastic beam 322 provided on one side of the force-receiving block 200 with respect to the second axial direction Y, and a seventh elastic beam 341 and an eighth elastic beam 342 on the other side.

[0063] Further, a plurality of force-sensitive resistors are all arranged in the first plane; a center point is provided in the first plane, and the force-sensitive resistors in the Wheatstone bridge for measuring the first force, the second force or the third force are rotationally symmetric about the center point in the first plane; the force-sensitive resistors in the Wheatstone bridge for measuring the first moment, the second moment and the third moment are symmetric about the first axial direction X or the second axial direction Y in the first plane.

[0064] Specifically, the force-receiving block 200 has a center point O in the first plane, and the center point O coincides with the geometric center of the force-receiving block 200; four groups of elastic members 300 are arranged in the gap 400 and connect the support frame 100 and the force-receiving block 200. The four groups of elastic members 300 are arranged on the outer periphery of the force-receiving block 200 and are rotationally symmetric about the center point O. The four groups of elastic members 300 are respectively arranged on both sides of the force-receiving block 200 with respect to the first axial direction X and both sides of the force-receiving block 200 with respect to the second axial direction Y. The extending directions of the elastic members 300 arranged on both sides of the force-receiving block 200 with respect to the first axial direction X extend along the second axial direction Y, and the extending directions of the elastic members 300 arranged on both sides of the force-receiving block 200 with respect to the second axial direction Y extend along the first axial direction X, and the extending directions between adjacent elastic members 300 are perpendicular to each other. Each group of elastic members 300 includes a pair of spaced elastic beams, and the elastic beams in each group of elastic members 300 are symmetric about the first axial direction X or the second axial direction Y. The extending directions of the elastic beams arranged on one side of the force-receiving block 200 in the first axial direction X or the second axial direction Y are collinear with those on the other side.

[0065] A number of force-sensitive resistors are arranged on the elastic beam to form six groups of Wheatstone bridges for measuring six-axis forces and torques respectively. The force-sensitive resistors are all arranged in the first plane of the elastic beam. Compared with the prior art in which the force-sensitive resistors are arranged in different planes, the present application greatly reduces the manufacturing process difficulty and manufacturing cost. Moreover, doping and manufacturing the force-sensitive resistors in the same plane can ensure consistent doping concentration, greatly improving the consistency of all force-sensitive resistor devices, and thus improving the measurement accuracy of the six-axis force sensor of the present application.

[0066] Further, the six-axis force sensor further has a third axis Z that intersects and is perpendicular to the first plane. The height of the support frame 100 in the third axis Z (i.e., its thickness direction) is greater than the heights of the force-receiving block 200 and the elastic member 300 in the third axis Z. That is, the height of the gap 400 in the third axis Z is greater than the heights of the force-receiving block 200 and the elastic member 300 in the third axis Z, so as to provide a movable space for the displacement of the force-receiving block 200 and the elastic member 300.

[0067] Combined with Figure 2 , Figure 3 As shown, the six groups of Wheatstone bridges are respectively used to measure the first force FX, the second force FY, the third force FZ, the first torque MX, the second torque MY, and the third torque MZ. Among them, the direction of the first force FX extends along the first axis X, the direction of the second force FY extends along the second axis Y, and the direction of the third force FZ extends along the third axis Z. According to the right-hand screw rule of torque, the direction of the first torque MX rotates counterclockwise around the first axis X, the direction of the second torque MY rotates counterclockwise around the second axis Y, and the direction of the third torque MZ rotates counterclockwise around the third axis Z.

[0068] Referring to Figure 4 As shown, Figure 4 a, b, c, d, e, f in show the schematic diagrams of the stress distributions of a six-axis force sensor according to an embodiment of the present application under the actions of the first force FX, the second force FY, the third force FZ, the first torque MX, the second torque MY, and the third torque MZ respectively. In the figure, green represents no stress distribution or low stress distribution, red represents that the result value of the stress in the first axis X direction minus the stress in the second axis Y direction is positive, blue represents that the result value of the stress in the first axis X direction minus the stress in the second axis Y direction is negative, and the darker the red or blue color, the greater the absolute value of the result value, that is, the greater the stress value received by the elastic beam.

[0069] Combined with Figure 1As shown, all the force-sensitive resistors in this application are arranged at the positions with relatively large stress on the elastic beam under the action of force or torque to form a full-bridge Wheatstone bridge. Compared with the single-bridge Wheatstone bridge or the double-bridge Wheatstone bridge where only some force-sensitive resistors are arranged at the positions with large stress and the remaining force-sensitive resistors are arranged at the positions with no stress distribution or low stress distribution, the sensitivity and accuracy of the full-bridge Wheatstone bridge in this application are higher. Since the number of force-sensitive resistors required to be arranged in the full-bridge Wheatstone bridge is more than that in the single-bridge Wheatstone bridge or the double-bridge Wheatstone bridge, the double-elastic-beam structure in this application provides a deployable space for the force-sensitive resistors of the full-bridge Wheatstone bridge.

[0070] Continue to refer to Figure 4 , when the six-axis force sensor is under the action of the first force FX, the second force FY, the first torque MX and the second torque MY, the stress distributions of the two elastic beams (i.e., the elastic beams in the elastic member 300 with the largest deformation) in the same group of elastic members 300 corresponding to the acting forces are symmetric about the first axis X or the second axis Y, and the stress distributions of the two collinear elastic beams in the two groups of elastic members 300 corresponding to the acting forces are opposite about the first axis X or the second axis Y (i.e., the stress magnitudes are equal and the directions are opposite). When the six-axis force sensor is under the action of the third force FZ, the stress distributions on all the elastic beams are the same. When the six-axis force sensor is under the action of the third torque MZ, the stress distributions of the two elastic beams in the same group of elastic members 300 are opposite, and the elastic members 300 arranged on both sides of the force-receiving block 200 about the first axis X are rotationally symmetric about the center point; the elastic members 300 arranged on both sides of the force-receiving block 200 about the second axis Y are rotationally symmetric about the center point.

[0071] Combined with Figure 2 , Figure 5 As shown, the elastic beam has a length L 1 , a width L 2 and a height L 3 ; for the length L 1 of the elastic beam, the longer the length L 1 of the elastic beam, the smaller the stress gradient on the elastic beam under the same force, and the easier it is to place the force-sensitive resistors; however, the increase in the length L 1 of the elastic beam will cause an increase in the size of the sensor chip. Therefore, considering the above factors comprehensively, when the force-sensitive resistor is under the action of the first force FX, the difference between the stress values at both ends of the force-sensitive resistor measuring the first force FX along the first axis X divided by the average stress on the first axis X is less than 0.002, and the length L 1 of the elastic beam is reasonably sized.

[0072] For the width L 2 of the elastic beam, the width L 2The smaller it is, the smaller the deformation resistance of the elastic beam and the higher the sensitivity of the force-sensitive resistor. However, when the width L of the elastic beam 2 is too narrow, the stress gradient change of the force-sensitive resistor for measuring the third moment MZ will be too large when it is under the action of the third moment MZ. Therefore, when the force-sensitive resistor for measuring the third moment MZ is under the action of the third moment MZ, the difference in the overall stress values at each point is within 20%. Set the width L of the elastic beam 2 to be more reasonable; in addition, the width L of the elastic beam 2 is also limited by the influence of the electrical signal transmission wire of the force-sensitive resistor. The width L of the elastic beam 2 should ensure the normal arrangement of the electrical signal transmission wire of the force-sensitive resistor and avoid cross-interference. Under the condition of ensuring the normal arrangement of the electrical signal transmission wire of the force-sensitive resistor and the stress distribution of the force-sensitive resistor for measuring the third moment MZ, the width L of the elastic beam 2 is preferably as narrow as possible.

[0073] Regarding the height L of the elastic beam 3 , under the condition of meeting the measurement range, the smaller the height L of the elastic beam 3 , the higher the sensitivity.

[0074] Combined with Figure 5 , Figure 6 as shown, Figure 5 and Figure 6 respectively show a schematic diagram of the distribution and a circuit schematic diagram of the force-sensitive resistors in a Wheatstone bridge for measuring the first force FX in a six-axis force sensor provided according to an embodiment of the present application. The Wheatstone bridge for measuring the first force FX is the first force FX bridge, and the first force FX bridge includes a first force-sensitive resistor FXR1, a second force-sensitive resistor FXR2, a third force-sensitive resistor FXR3, and a fourth force-sensitive resistor FXR4. Among them, the first force-sensitive resistor FXR1 and the second force-sensitive resistor FXR2 are respectively arranged on the eighth elastic beam 342 and the seventh elastic beam 341, and the third force-sensitive resistor FXR3 and the fourth force-sensitive resistor FXR4 are respectively arranged on the fourth elastic beam 322 and the third elastic beam 321. Combined with Figure 4Schematic diagram of the stress distribution of the six-axis force sensor in Embodiment 6 at position a under the action of the first force FX in the first axial direction X. The force-receiving block 200 is displaced along the first axial direction X under the action of the first force FX. The seventh elastic beam 341 and the eighth elastic beam 342 are stressed in the direction of the first axial direction X as the force-receiving block 200 is displaced. The third elastic beam 321 and the fourth elastic beam 322 are stressed in the direction of the second direction Y as the force-receiving block 200 is displaced. The first force-sensitive resistor FXR1, the second force-sensitive resistor FXR2, the third force-sensitive resistor FXR3, and the fourth force-sensitive resistor FXR4 are all arranged at positions where the stress of the elastic beam is relatively large. The first force-sensitive resistor FXR1 and the second force-sensitive resistor FXR2 have their resistance values increased under the action of the stress in the first axial direction X (equivalent to the resistor being stretched), and the third force-sensitive resistor FXR3 and the fourth force-sensitive resistor FXR4 have their resistance values decreased under the action of the stress in the second axial direction Y (equivalent to the resistor being widened). The first force-sensitive resistor FXR1 and the third force-sensitive resistor FXR3 are rotationally symmetric about the center point by 180°, and the second force-sensitive resistor FXR2 and the fourth force-sensitive resistor FXR4 are rotationally symmetric about the center point by 180°. Combining Figure 6 As shown, the first force-sensitive resistor FXR1 and the second force-sensitive resistor FXR2 are arranged diagonally in the bridge, and the third force-sensitive resistor FXR3 and the fourth force-sensitive resistor FXR4 are arranged diagonally in the bridge.

[0075] Furthermore, the first force-sensitive resistor FXR1, the second force-sensitive resistor FXR2, the third force-sensitive resistor FXR3, and the fourth force-sensitive resistor FXR4 can be arranged at positions of 1 / 6 to 1 / 2 of the elastic beam close to the support frame 100. For example, 1 / 6, 1 / 5, 1 / 4, 1 / 3, 1 / 2. This can not only arrange the first to fourth force-sensitive resistors at positions where the stress of the elastic beam is relatively large, improving the measurement sensitivity to the first force FX, but also provide layout space for the force-sensitive resistors of other Wheatstone bridges. The changes in the resistance values of the first force-sensitive resistor FXR1, the second force-sensitive resistor FXR2, the third force-sensitive resistor FXR3, and the fourth force-sensitive resistor FXR4 in the first force FX bridge under the action of six-axis forces and the signal output situation of the Wheatstone bridge are shown in Table 1 below (where "+Δ" and "-Δ" respectively represent an increase or decrease in the resistance value of the force-sensitive resistor by the same value Δ, and "+Δ" and "-Δ" have the same meaning in all tables hereinafter):

[0076] Table 1

[0077]

[0078] Since the full-arm Wheatstone bridge needs to meet the signal output conditions that the change trends of the force-sensitive resistors at the diagonals in the bridge are in the same direction (both increasing or both decreasing) and the change values are equal, and the change trends of the force-sensitive resistors on the same side are in the opposite direction (one increases and the other decreases) and the change values are equal. The first force FX bridge under the action of the first force FX meets the above signal output conditions and outputs a signal. Under the actions of the second force FY, the third force FZ, the first moment MX, the second moment MY, and the third moment MZ, the first force FX bridge does not meet the signal output conditions and no signal is output, avoiding signal errors caused by the influence of non-measured forces and moments on the first force FX bridge, realizing the self-decoupling between the measured forces and moments and the non-measured forces and moments, and improving the accuracy of the six-axis force sensor of the present application.

[0079] Combined with Figure 7 , Figure 8 as shown, Figure 7 and Figure 8 respectively show a schematic diagram of the distribution of force-sensitive resistors and a schematic circuit diagram in a Wheatstone bridge for measuring the second force FY in a six-axis force sensor according to an embodiment of the present application. The Wheatstone bridge for measuring the second force FY is the second force FY bridge. The second force FY bridge includes a fifth force-sensitive resistor FYR1, a sixth force-sensitive resistor FYR2, a seventh force-sensitive resistor FYR3, and an eighth force-sensitive resistor FYR4. Among them, the fifth force-sensitive resistor FYR1 and the eighth force-sensitive resistor FYR4 are respectively arranged on the first elastic beam 311 and the second elastic beam 312, and the sixth force-sensitive resistor FYR2 and the seventh force-sensitive resistor FYR3 are respectively arranged on the sixth elastic beam 332 and the fifth elastic beam 331. Combined with Figure 4 the schematic diagram of the stress distribution in the case where the six-axis force sensor at b in Figure 8As shown, the fifth force-sensitive resistor FYR1 and the eighth force-sensitive resistor FYR4 are arranged diagonally in the bridge, and the sixth force-sensitive resistor FYR2 and the seventh force-sensitive resistor FYR3 are arranged diagonally in the bridge.

[0080] Further, the fifth force-sensitive resistor FYR1, the sixth force-sensitive resistor FYR2, the seventh force-sensitive resistor FYR3, and the eighth force-sensitive resistor FYR4 can be arranged at the position of 1 / 6 to 1 / 2 of the elastic beam close to the support frame 100. For example, 1 / 6, 1 / 5, 1 / 4, 1 / 3, 1 / 2. This can not only arrange the fifth to eighth force-sensitive resistors at the position with greater stress of the elastic beam to improve the measurement sensitivity of the second force FY, but also provide layout space for the force-sensitive resistors of other Wheatstone bridges.

[0081] The resistance value changes of the fifth force-sensitive resistor FYR1, the sixth force-sensitive resistor FYR2, the seventh force-sensitive resistor FYR3, and the eighth force-sensitive resistor FYR4 in the second force FY bridge under the action of six-axis forces and the output of the Wheatstone bridge are shown in Table 2 below:

[0082] Table 2

[0083]

[0084] The second force FY bridge outputs a signal under the action of the second force FY and satisfies the above signal output conditions. Under the action of the first force FX, the third force FZ, the first moment MX, the second moment MY, and the third moment MZ, the second force FY bridge does not satisfy the signal output conditions and no signal is output. This avoids signal errors caused by the second force FY bridge being affected by non-measured forces and moments, realizes the self-decoupling between measured forces and moments and non-measured forces and moments, and improves the accuracy of the six-axis force sensor of the present application.

[0085] Combined with Figure 9 、 Figure 10 shown, Figure 9 and Figure 10 respectively show a schematic diagram of the distribution of force-sensitive resistors and a schematic circuit diagram in the Wheatstone bridge for measuring the third force FZ in a six-axis force sensor provided according to an embodiment of the present application. The Wheatstone bridge for measuring the third force FZ is the third force FZ bridge, and the third force FZ bridge includes a ninth force-sensitive resistor FZR1, a tenth force-sensitive resistor FZR2, an eleventh force-sensitive resistor FZR3, and a twelfth force-sensitive resistor FZR4. Among them, the ninth force-sensitive resistor FZR1 and the tenth force-sensitive resistor FZR2 are respectively arranged at both ends of the seventh elastic beam 341, and the eleventh force-sensitive resistor FZR3 and the twelfth force-sensitive resistor FZR4 are respectively arranged at both ends of the third elastic beam 321. Combined with Figure 4Schematic diagram of stress distribution when the six-axis force sensor at position c is under the action of the third force FZ in the third axial direction Z. The ninth force-sensitive resistor FZR1, the tenth force-sensitive resistor FZR2, the eleventh force-sensitive resistor FZR3, and the twelfth force-sensitive resistor FZR4 are all arranged at positions with relatively large stress on the elastic beam. The force-receiving block 200 is displaced along the third axial direction Z under the action of the third force FZ, and both ends of the third elastic beam 321 and the seventh elastic beam 341 are bent. From Figure 4 As can be seen from c, the ends of the third elastic beam 321 and the seventh elastic beam 341 close to the force-receiving block 200 are subjected to stress in the first axial direction X. Therefore, the tenth force-sensitive resistor FZR2 arranged at the end of the seventh elastic beam 341 close to the force-receiving block 200 and the eleventh force-sensitive resistor FZR3 arranged at the end of the third elastic beam 321 close to the force-receiving block 200 are subjected to stress in the first axial direction X and their resistance values increase (equivalent to the resistance being stretched). The ends of the third elastic beam 321 and the seventh elastic beam 341 close to the support frame 100 are subjected to stress in the second axial direction Y. Therefore, the ninth force-sensitive resistor FZR1 arranged at the end of the seventh elastic beam 341 close to the support frame 100 and the twelfth force-sensitive resistor FZR4 arranged at the end of the third elastic beam 321 close to the support frame 100 have their resistance values decreased due to being subjected to stress in the second axial direction Y (equivalent to the resistance being widened). The ninth force-sensitive resistor FZR1 and the twelfth force-sensitive resistor FZR4 are rotationally symmetric about the center point by 180°. The tenth force-sensitive resistor FZR2 and the eleventh force-sensitive resistor FZR3 are rotationally symmetric about the center point by 180°. Combining Figure 10 As shown, the ninth force-sensitive resistor FZR1 and the twelfth force-sensitive resistor FZR4 are arranged diagonally in the bridge. The tenth force-sensitive resistor FZR2 and the eleventh force-sensitive resistor FZR3 are arranged diagonally in the bridge.

[0086] The changes in the resistance values of the ninth force-sensitive resistor FZR1, the tenth force-sensitive resistor FZR2, the eleventh force-sensitive resistor FZR3, and the twelfth force-sensitive resistor FZR4 in the third-force FZ bridge under the action of six-axis forces and the output situation of the Wheatstone bridge signal are shown in Table 3 below:

[0087] Table 3

[0088]

[0089] The third-force FZ bridge under the action of the third force FZ satisfies the above signal output conditions and outputs a signal. Under the action of the first force FX, the second force FY, the first moment MX, the second moment MY, and the third moment MZ, the third-force FZ bridge does not satisfy the signal output conditions and no signal is output, avoiding signal errors caused by the third-force FZ bridge being affected by non-measured forces and moments, realizing the self-decoupling between measured forces and moments and non-measured forces and moments, and improving the accuracy of the six-axis force sensor of the present application.

[0090] It should be noted that, in this embodiment, the ninth force-sensitive resistor FZR1, the tenth force-sensitive resistor FZR2, the eleventh force-sensitive resistor FZR3, and the twelfth force-sensitive resistor FZR4 of the third-force FZ bridge are arranged on the third elastic beam 321 and the seventh elastic beam 341. In another embodiment, the ninth force-sensitive resistor FZR1, the tenth force-sensitive resistor FZR2, the eleventh force-sensitive resistor FZR3, and the twelfth force-sensitive resistor FZR4 can also be arranged on the fourth elastic beam 322 and the eighth elastic beam 342, or on the first elastic beam 311 and the fifth elastic beam 331 according to actual requirements. The ninth force-sensitive resistor FZR1, the tenth force-sensitive resistor FZR2, the eleventh force-sensitive resistor FZR3, and the twelfth force-sensitive resistor FZR4 are arranged on elastic beams that are opposite and non-collinear with respect to the first axis X or the second axis Y, and no specific limitation is made here. The ninth force-sensitive resistor FZR1, the tenth force-sensitive resistor FZR2, the eleventh force-sensitive resistor FZR3, and the twelfth force-sensitive resistor FZR4 are arranged on elastic beams that are opposite and non-collinear with respect to the first axis X or the second axis Y to avoid signal errors in the third-force FZ bridge caused by the action of non-measured forces and torques.

[0091] Referring to Figure 11 、 Figure 12 as shown, Figure 11 and Figure 12 respectively show a schematic diagram of the distribution of force-sensitive resistors and a schematic circuit diagram in a Wheatstone bridge for measuring the first torque MX in a six-axis force sensor provided according to an embodiment of the present application. The Wheatstone bridge for measuring the first torque MX is the first-torque MX bridge, and the first-torque MX bridge includes a thirteenth force-sensitive resistor MXR1, a fourteenth force-sensitive resistor MXR2, a fifteenth force-sensitive resistor MXR3, and a sixteenth force-sensitive resistor MXR4. Among them, the thirteenth force-sensitive resistor MXR1 and the fourteenth force-sensitive resistor MXR2 are respectively arranged at both ends of the first elastic beam 311, the fifteenth force-sensitive resistor MXR3 and the sixteenth force-sensitive resistor MXR4 are respectively arranged at both ends of the sixth elastic beam 332, the thirteenth force-sensitive resistor MXR1 and the fourteenth force-sensitive resistor MXR2 are both arranged at the midline position of the first elastic beam 311, the fifteenth force-sensitive resistor MXR3 and the sixteenth force-sensitive resistor MXR4 are both arranged at the midline position of the sixth elastic beam 332. Since the axes of the first elastic beam 311 and the sixth elastic beam 332 are collinear, the thirteenth force-sensitive resistor MXR1, the fourteenth force-sensitive resistor MXR2, the fifteenth force-sensitive resistor MXR3, and the sixteenth force-sensitive resistor MXR4 are arranged collinearly. Combining Figure 4Schematic diagram of the stress distribution when the six-axis force sensor at position d is subjected to the first moment MX about the first axis X. The thirteenth force-sensitive resistor MXR1, the fourteenth force-sensitive resistor MXR2, the fifteenth force-sensitive resistor MXR3, and the sixteenth force-sensitive resistor MXR4 are all arranged at the positions with relatively large stress of the elastic beam. The force-receiving block 200 rotates about the first axis X under the action of the first moment MX, and both ends of the first elastic beam 311 and the sixth elastic beam 332 are bent. The end of the first elastic beam 311 close to the force-receiving block 200 and the end of the sixth elastic beam 332 close to the support frame 100 are subjected to stress in the second axis Y direction. Therefore, the fourteenth force-sensitive resistor MXR2 arranged at the end of the first elastic beam 311 close to the force-receiving block 200 and the sixteenth force-sensitive resistor MXR4 arranged at the end of the sixth elastic beam 332 close to the support frame 100 have increased resistance values due to the stress in the second axis Y direction. The end of the first elastic beam 311 close to the support frame 100 and the end of the sixth elastic beam 332 close to the force-receiving block 200 are subjected to stress in the first axis X direction. Therefore, the thirteenth force-sensitive resistor MXR1 arranged at the end of the first elastic beam 311 close to the support frame 100 and the fifteenth force-sensitive resistor MXR3 arranged at the end of the sixth elastic beam 332 close to the force-receiving block 200 have decreased resistance values due to the stress in the first axis X direction. The thirteenth force-sensitive resistor MXR1 and the sixteenth force-sensitive resistor MXR4 are symmetrically arranged about the first axis X, and the fourteenth force-sensitive resistor MXR2 and the fifteenth force-sensitive resistor MXR3 are symmetrically arranged about the first axis X. Combined with Figure 12 As shown, the thirteenth force-sensitive resistor MXR1 and the fifteenth force-sensitive resistor MXR3 are arranged diagonally in the bridge, and the fourteenth force-sensitive resistor MXR2 and the sixteenth force-sensitive resistor MXR4 are arranged diagonally in the bridge.

[0092] The resistance value changes of the thirteenth force-sensitive resistor MXR1, the fourteenth force-sensitive resistor MXR2, the fifteenth force-sensitive resistor MXR3, and the sixteenth force-sensitive resistor MXR4 in the first moment MX bridge under the action of six-axis force and the Wheatstone bridge signal output are as shown in Table 4 below:

[0093] Table 4

[0094]

[0095] The first moment MX bridge under the action of the first moment MX satisfies the above signal output conditions and outputs a signal. Under the action of the first force FX, the second force FY, the third force FZ, the second moment MY, and the third moment MZ, the first moment MX bridge does not satisfy the signal output conditions and has no signal output, avoiding signal errors caused by the influence of non-measured forces and moments on the first moment MX bridge, realizing the self-decoupling between measured forces and moments and non-measured forces and moments, and improving the accuracy of the six-axis force sensor of the present application.

[0096] It should be noted that, in this embodiment, the thirteenth force-sensitive resistor MXR1, fourteenth force-sensitive resistor MXR2, fifteenth force-sensitive resistor MXR3, and sixteenth force-sensitive resistor MXR4 of the first moment MX bridge are disposed on the first elastic beam 311 and the sixth elastic beam 332. In some other embodiments, the thirteenth force-sensitive resistor MXR1, fourteenth force-sensitive resistor MXR2, fifteenth force-sensitive resistor MXR3, and sixteenth force-sensitive resistor MXR4 are disposed on the second elastic beam 312 and the fifth elastic beam 331 that are opposite and collinear. No specific limitation is made here.

[0097] Combined with Figure 13 , Figure 14 as shown, Figure 13 and Figure 14 respectively show a schematic diagram of the distribution of force-sensitive resistors in a Wheatstone bridge for measuring the second moment MY and a schematic circuit diagram in a six-axis force sensor according to an embodiment of the present application. The Wheatstone bridge for measuring the second moment MY is the second moment MY bridge. The second moment MY bridge includes a seventeenth force-sensitive resistor MYR1, an eighteenth force-sensitive resistor MYR2, a nineteenth force-sensitive resistor MYR3, and a twentieth force-sensitive resistor MYR4. Among them, the seventeenth force-sensitive resistor MYR1 and the eighteenth force-sensitive resistor MYR2 are respectively disposed at both ends of the eighth elastic beam 342, the nineteenth force-sensitive resistor MYR3 and the twentieth force-sensitive resistor MYR4 are respectively disposed at both ends of the third elastic beam 321. The seventeenth force-sensitive resistor MYR1 and the eighteenth force-sensitive resistor MYR2 are both disposed at the midline position of the eighth elastic beam 342, and the nineteenth force-sensitive resistor MYR3 and the twentieth force-sensitive resistor MYR4 are both disposed at the midline position of the third elastic beam 321. Since the axes of the third elastic beam 321 and the eighth elastic beam 342 are collinear, the seventeenth force-sensitive resistor MYR1, the eighteenth force-sensitive resistor MYR2, the nineteenth force-sensitive resistor MYR3, and the twentieth force-sensitive resistor MYR4 are disposed collinearly. Combined with Figure 4Schematic diagram of the stress distribution when the six-axis force sensor at position e is subjected to the second moment MY about the second axis Y. The seventeenth force-sensitive resistor MYR1, the eighteenth force-sensitive resistor MYR2, the nineteenth force-sensitive resistor MYR3, and the twentieth force-sensitive resistor MYR4 are all arranged at the positions with relatively large stress on the elastic beam. The force-receiving block 200 rotates about the second axis Y under the action of the second moment MY, and both ends of the third elastic beam 321 and the eighth elastic beam 342 are bent. The end of the eighth elastic beam 342 close to the force-receiving block 200 and the end of the third elastic beam 321 close to the support frame 100 are subjected to stress in the first axial X direction. Therefore, the eighteenth force-sensitive resistor MYR2 arranged at the end of the eighth elastic beam 342 close to the force-receiving block 200 and the twentieth force-sensitive resistor MYR4 arranged at the end of the third elastic beam 321 close to the support frame 100 have increased resistance values due to the stress in the first axial X direction. The end of the eighth elastic beam 342 close to the support frame 100 and the end of the third elastic beam 321 close to the force-receiving block 200 are subjected to stress in the second axial Y direction. Therefore, the seventeenth force-sensitive resistor MYR1 arranged at the end of the eighth elastic beam 342 close to the support frame 100 and the nineteenth force-sensitive resistor MYR3 arranged at the end of the third elastic beam 321 close to the force-receiving block 200 have decreased resistance values due to the stress in the second axial Y direction. The seventeenth force-sensitive resistor MYR1 and the twentieth force-sensitive resistor MYR4 are symmetrically arranged about the second axis Y, and the eighteenth force-sensitive resistor MYR2 and the nineteenth force-sensitive resistor MYR3 are symmetrically arranged about the second axis Y. Combining Figure 14 As shown, the seventeenth force-sensitive resistor MYR1 and the nineteenth force-sensitive resistor MYR3 are arranged diagonally in the bridge, and the eighteenth force-sensitive resistor MYR2 and the twentieth force-sensitive resistor MYR4 are arranged diagonally in the bridge.

[0098] The resistance value changes of the seventeenth force-sensitive resistor MYR1, the eighteenth force-sensitive resistor MYR2, the nineteenth force-sensitive resistor MYR3, and the twentieth force-sensitive resistor MYR4 in the second moment MY bridge under the action of six-axis forces and the Wheatstone bridge signal output are shown in Table 5 below:

[0099] Table 5

[0100]

[0101] The second moment MY bridge under the action of the second moment MY satisfies the above signal output conditions and outputs a signal. Under the action of the first force FX, the second force FY, the third force FZ, the first moment MX, and the third moment MZ, the second moment MY bridge does not satisfy the signal output conditions and no signal is output, avoiding signal errors caused by the influence of non-measured forces and moments on the second moment MY bridge, realizing the self-decoupling between measured forces and moments and non-measured forces and moments, and improving the accuracy of the six-axis force sensor of the present application.

[0102] Further, referring to Figure 4 e, 4c, and Figure 9 , Figure 13 , since the end of the third elastic beam 321 close to the force-receiving block 200 is subjected to relatively large stresses under the action of the third force FZ and the second moment MY, therefore, the nineteenth force-sensitive resistor MYR3 and the eleventh force-sensitive resistor FZR3 can share the same force-sensitive resistor. At the same time, since the end of the third elastic beam 321 close to the support frame 100 is subjected to relatively large stresses under the action of the third force FZ and the second moment MY, the twentieth force-sensitive resistor MYR4 and the twelfth force-sensitive resistor FZR4 can share the same force-sensitive resistor. The Wheatstone bridges for measuring different axial forces can share the same force-sensitive resistor, which further provides a deployable space for arranging the force-sensitive resistors for measuring the forces of each axis to achieve a full-arm Wheatstone bridge arrangement.

[0103] Combined with Figure 15 , Figure 16 shown, Figure 15 and Figure 16 respectively show a schematic diagram of the distribution of force-sensitive resistors and a circuit schematic diagram in a Wheatstone bridge for measuring the third moment MZ in a six-axis force sensor provided according to an embodiment of the present application. The Wheatstone bridge for measuring the third moment MZ is the third moment MZ bridge, and the third moment MZ bridge includes a twenty-first force-sensitive resistor MZR1, a twenty-second force-sensitive resistor MZR2, a twenty-third force-sensitive resistor MZR3, and a twenty-fourth force-sensitive resistor MZR4. Among them, the twenty-first force-sensitive resistor MZR1 is arranged at the end of the first elastic beam 311 close to the force-receiving block 200, and the twenty-first force-sensitive resistor MZR1 is arranged at the edge position of the first elastic beam 311 far from the second elastic beam 312; the twenty-second force-sensitive resistor MZR2 is arranged at the end of the sixth elastic beam 332 close to the force-receiving block 200, and the twenty-second force-sensitive resistor MZR2 is arranged at the edge position of the sixth elastic beam 332 far from the fifth elastic beam 331; the twenty-third force-sensitive resistor MZR3 is arranged at the end of the fifth elastic beam 331 close to the force-receiving block 200, and the twenty-third force-sensitive resistor MZR3 is arranged at the edge position of the fifth elastic beam 331 far from the sixth elastic beam 332; the twenty-fourth force-sensitive resistor MZR4 is arranged at the position of the second elastic beam 312 close to the force-receiving block 200, and the twenty-fourth force-sensitive resistor MZR4 is arranged at the edge position of the second elastic beam 312 far from the first elastic beam 311. Combined with Figure 4 the schematic diagram of the stress distribution in the case where the six-axis force sensor at f in Figure 4It can be seen that the twenty-first force-sensitive resistor MZR1 is subjected to the stress in the second axial Y direction. Therefore, the resistance value of the twenty-first force-sensitive resistor MZR1 increases. The twenty-fourth force-sensitive resistor MZR4 is subjected to the stress in the first axial X direction. Therefore, the resistance value of the twenty-fourth force-sensitive resistor MZR4 decreases. The twenty-second force-sensitive resistor MZR2 is subjected to the stress in the first axial X direction. Therefore, the resistance value of the twenty-second force-sensitive resistor MZR2 decreases. The twenty-third force-sensitive resistor MZR3 is subjected to the stress in the second axial Y direction. Therefore, the resistance value of the twenty-third force-sensitive resistor MZR3 increases. The twenty-first force-sensitive resistor MZR1 and the twenty-second force-sensitive resistor MZR2 are symmetrically arranged with respect to the first axial X. The twenty-third force-sensitive resistor MZR3 and the twenty-fourth force-sensitive resistor MZR4 are symmetrically arranged with respect to the first axial X. Combining Figure 16 As shown, the twenty-first force-sensitive resistor MZR1 and the twenty-third force-sensitive resistor MZR3 are diagonally arranged in the bridge. The twenty-second force-sensitive resistor MZR2 and the twenty-fourth force-sensitive resistor MZR4 are diagonally arranged in the bridge.

[0104] The resistance value changes of the twenty-first force-sensitive resistor MZR1, the twenty-second force-sensitive resistor MZR2, the twenty-third force-sensitive resistor MZR3, and the twenty-fourth force-sensitive resistor MZR4 in the third moment MZ bridge under the action of six-axis forces and the Wheatstone bridge signal output are shown in Table 6 below:

[0105] Table 6

[0106]

[0107] The third moment MZ bridge under the action of the third moment MZ satisfies the above signal output conditions and outputs a signal. Under the action of the first force FX, the second force FY, the third force FZ, the first moment MX, and the second moment MY, the third moment MZ bridge does not satisfy the signal output conditions and no signal is output, avoiding signal errors caused by the third moment MZ bridge being affected by non-measured forces and moments, realizing the self-decoupling between measured forces and moments and non-measured forces and moments, and improving the accuracy of the six-axis force sensor of the present application.

[0108] In summary, the elastic member 300 of the present application adopts a double elastic beam structure. Compared with the single elastic beam structure in the prior art, the double elastic beam structure provides a deployable space for the force-sensitive resistors of the six-axis full-arm Wheatstone bridge, avoids signal errors caused by the Wheatstone bridge being affected by non-measured forces and moments, realizes the self-decoupling between measured forces and moments and non-measured forces and moments, and improves the accuracy of the six-axis force sensor of the present application.

[0109] It should be noted that the arrangement design of the force-sensitive resistors in this application is such that only for the measured force and torque, the corresponding Wheatstone bridge will generate a signal output, while the other five-axis forces and torques do not change the force-sensitive resistors used in this Wheatstone bridge, or the generated resistance value changes are offset by this Wheatstone bridge, and the bridge does not lose balance, and the output signal can be ignored. That is, the Wheatstone bridge only generates an output signal under the action of the corresponding force and torque, and under the action of other forces and torques, the current Wheatstone bridge is not affected or the output signal can be ignored. Therefore, the requirement of simultaneously and independently detecting six-axis forces and torques is met.

[0110] It should also be noted that not all of the force-sensitive resistors in this embodiment are arranged at the position with the maximum stress under the action of the force or torque they are used to measure. The arrangement of the force-sensitive resistors needs to consider that the force-sensitive resistors in all Wheatstone bridges are arranged at relatively large and separated positions, so as to avoid the increase in manufacturing process difficulty and manufacturing cost caused by the force-sensitive resistors being too close to each other, and at the same time, it can also avoid the measurement error caused by the coupling between the measured force and torque and the non-measured force and torque.

[0111] It should also be noted that the six groups of Wheatstone bridges in this embodiment are all full-arm Wheatstone bridges. In some other embodiments, some of the above six groups of Wheatstone bridges can be single-arm Wheatstone bridges or double-arm Wheatstone bridges. Compared with the six groups of full-arm Wheatstone bridges in this embodiment, the number of force-sensitive resistors that need to be set is less, and the positions where the force-sensitive resistors can be arranged are more, which can better achieve the self-decoupling between the measured force and torque and the non-measured force and torque, and no specific limitation is made here.

[0112] This application further provides a method for manufacturing a six-axis force sensor. The method for manufacturing a six-axis force sensor includes:

[0113] S10, providing a silicon wafer, and forming an oxide layer on one side surface of the silicon wafer;

[0114] S20, performing patterning on the oxide layer to form a force-sensitive resistor pattern, and doping the silicon wafer at the position of the force-sensitive resistor pattern to form a force-sensitive resistor in the silicon wafer;

[0115] S30, performing patterning on the oxide layer to form an ohmic contact layer pattern, and doping the silicon wafer at the position of the ohmic contact layer pattern to form an ohmic contact layer on the surface layer of the silicon wafer, and the ohmic contact layer connects the force-sensitive resistor; etching the ohmic contact layer to form a plurality of ohmic contact areas corresponding to the force-sensitive resistors one by one; annealing to activate the force-sensitive resistor and the ohmic contact area;

[0116] S40, forming a wiring on one side surface of the silicon wafer having the ohmic contact area, and the wiring connects the force-sensitive resistor through the ohmic contact area;

[0117] S50, Pattern and etch the surface of the silicon wafer on the side away from the trace to form the support frame 100 to the thickness positions of the stress-bearing block 200 and the elastic member 300;

[0118] S60, Pattern and etch the area other than the support frame 100 on the surface of the silicon wafer on the side away from the trace to form the stress-bearing block 200 and the elastic member 300.

[0119] Steps S10 to S60 will be specifically described below.

[0120] In step S10, a silicon wafer is provided. This silicon wafer is a double-polished silicon wafer with an N-type crystal plane. A thin oxide layer is formed on the surface of the silicon wafer by thermal oxidation. This oxide layer is used to scatter ions during subsequent ion implantation to reduce the channeling effect.

[0121] In step S20, using photoresist as a mask, the oxide layer is patterned to form a piezoresistive resistor pattern. After patterning, the silicon wafer at the position of the piezoresistive resistor pattern is doped by ion implantation to form a piezoresistive resistor in the silicon wafer.

[0122] In step S30, using photoresist as a mask, the oxide layer is patterned to form an ohmic contact layer pattern. The silicon wafer at the position of the ohmic contact layer pattern is doped by ion implantation to form an ohmic contact layer for interconnecting the piezoresistive resistor and the trace on the surface layer of the silicon wafer.

[0123] Using photoresist as a mask, a plurality of ohmic contact area patterns are formed on the ohmic contact layer. The ohmic contact layer is etched open by reactive ion etching (RIE) to form a plurality of ohmic contact areas corresponding one-to-one to the piezoresistive resistors.

[0124] A dielectric layer is formed on the surface of the silicon wafer by plasma-enhanced chemical vapor deposition (PECVD). This dielectric layer includes silicon oxide and / or silicon nitride. The dielectric layer serves as a passivation layer on the surface of the silicon wafer and is annealed in a nitrogen environment at 1150 °C for 30 minutes to activate the implanted ions.

[0125] In step S40, a metal layer is formed by sputtering or evaporation. Part of the metal layer is removed from the metal layer by etching or stripping. The remaining metal layer forms the trace. The trace is annealed and alloyed. This trace is connected to the piezoresistive resistor through the ohmic contact area.

[0126] A silicon nitride layer is formed on the surface of the silicon wafer provided with the trace by plasma-enhanced chemical vapor deposition (PECVD). The silicon nitride layer is used to protect the trace.

[0127] In step S50, spin coating and patterning are performed on the surface of the silicon wafer on the side away from the wiring, and the silicon wafer is etched by deep silicon etching process (Bosch process) to form the support frame 100 and etch to the thickness positions of the stress block 200 and the elastic member 300.

[0128] In step S60, spin coating and patterning are performed on the surface of the silicon wafer on the side with the wiring, and the silicon wafer is etched by deep silicon etching process (Bosch process) to form the stress block 200 and the elastic member 300 and make the two suspended.

[0129] By arranging a number of force-sensitive resistors on the elastic beam to form six groups of Wheatstone bridges respectively for measuring six-axis force and torque, the force-sensitive resistors are all arranged in the same plane of the elastic beam. Compared with the prior art technical solution in which the force-sensitive resistors are arranged in different planes, the present application greatly reduces the manufacturing process difficulty and manufacturing cost, and doping and manufacturing the force-sensitive resistors in the same plane can ensure the same doping concentration, greatly improving the consistency of all force-sensitive resistor devices, and further improving the measurement accuracy of the six-axis force sensor of the present application.

[0130] The technical features of the above-described embodiments can be combined arbitrarily. For the sake of brevity of description, not all possible combinations of the technical features in the above-described embodiments are described. However, as long as there is no contradiction in the combination of these technical features, it should be considered to be within the scope described in this specification.

[0131] The above-described embodiments only represent several implementation manners of the present application, and the description thereof is relatively specific and detailed, but it should not be construed as a limitation on the scope of the patent application. It should be noted that for those of ordinary skill in the art, without departing from the concept of the present application, several modifications and improvements can be made, and these all belong to the protection scope of the present application. Therefore, the protection scope of the patent of the present application shall be subject to the appended claims.

Claims

1. A six-axis force sensor, characterized in that: include: Load bearing block; A supporting frame, wherein the supporting frame surrounds the force-bearing block, and a gap is provided between the force-bearing block and the supporting frame; A plurality of groups of elastic members, the plurality of groups of elastic members are arranged in the gap and are respectively connected to the force-bearing block and the support frame, the plurality of groups of elastic members divide the gap into a plurality of first deformation cavities, and the first deformation cavities are used to accommodate the deformation of the elastic members; Each group of the elastic members is composed of a pair of elastic beams arranged at intervals; any pair of the elastic beams, the force-bearing block and the support frame enclose a second deformation cavity, and the second deformation cavity is used to accommodate the deformation of the elastic beams; A plurality of force-sensitive resistors, wherein the plurality of force-sensitive resistors are arranged in the elastic beam to form six groups of Wheatstone bridges, each of which is composed of four force-sensitive resistors and is used to measure the first force, the second force, the third force, the first moment, the second moment and the third moment respectively; The six-axis force sensor has a first plane, and has a first axial direction and a second axial direction that intersect and are perpendicular to each other in the first plane. The direction of the first force extends along the first axial direction, the direction of the second force extends along the second axial direction, and the direction of the third force extends along a third axial direction that is perpendicular to the first plane. A side surface of the elastic member is in the first plane. The plurality of force-sensitive resistors are all arranged in the first plane. A center point is provided in the first plane. The force-sensitive resistors in the Wheatstone bridge for measuring the first force, the second force or the third force are rotationally symmetric about the center point in the first plane. The force-sensitive resistors in the Wheatstone bridge for measuring the first torque, the second torque and the third torque are symmetric about the first axial direction or the second axial direction in the first plane. Among them, the two force-sensitive resistors in the Wheatstone bridge for measuring the first force are respectively arranged on a pair of the elastic beams on one side of the force-bearing block with respect to the second axial direction, and the other two force-sensitive resistors are respectively arranged on a pair of the elastic beams on the other side; the two force-sensitive resistors in the Wheatstone bridge for measuring the second force are respectively arranged on a pair of the elastic beams on one side of the force-bearing block with respect to the first axial direction, and the other two force-sensitive resistors are respectively arranged on a pair of the elastic beams on the other side; the two force-sensitive resistors in the Wheatstone bridge for measuring the third force are arranged on one of the elastic beams on one side of the force-bearing block with respect to the first axial direction or the second axial direction, and the other two force-sensitive resistors are both arranged on one of the elastic beams on the other side.

2. The six-axis force sensor according to claim 1, characterized in that: The elastic beams in the same group of elastic members are symmetrical about the first axial direction or the second axial direction.

3. The six-axis force sensor according to any one of claims 1 to 2, characterized in that: The Wheatstone bridges used for measuring the first force, the second force, the third force, the first moment, the second moment and the third moment are all full-arm Wheatstone bridges.

4. The six-axis force sensor according to claim 2, wherein: The plurality of force-sensitive resistors include a first force-sensitive resistor, a second force-sensitive resistor, a third force-sensitive resistor and a fourth force-sensitive resistor for measuring a first force, the first force-sensitive resistor and the second force-sensitive resistor are respectively arranged on a pair of the elastic beams on one side of the force-bearing block about the second axial direction, and the third force-sensitive resistor and the fourth force-sensitive resistor are respectively arranged on a pair of the elastic beams on the other side; the first force-sensitive resistor and the second force-sensitive resistor are diagonally arranged in the bridge, and the third force-sensitive resistor and the fourth force-sensitive resistor are diagonally arranged in the bridge; The plurality of force-sensitive resistors further include a fifth force-sensitive resistor, a sixth force-sensitive resistor, a seventh force-sensitive resistor and an eighth force-sensitive resistor for measuring the second force, the fifth force-sensitive resistor and the eighth force-sensitive resistor are respectively arranged on a pair of the elastic beams on one side of the force-bearing block about the first axial direction, and the sixth force-sensitive resistor and the seventh force-sensitive resistor are respectively arranged on a pair of the elastic beams on the other side; the fifth force-sensitive resistor and the eighth force-sensitive resistor are diagonally arranged in the bridge, and the sixth force-sensitive resistor and the seventh force-sensitive resistor are diagonally arranged in the bridge; The multiple force-sensitive resistors also include a ninth force-sensitive resistor, a tenth force-sensitive resistor, an eleventh force-sensitive resistor and a twelfth force-sensitive resistor for measuring the third force. The ninth force-sensitive resistor and the tenth force-sensitive resistor are arranged on one of the elastic beams on one side of the force-bearing block about the first axial direction or the second axial direction, and the eleventh force-sensitive resistor and the twelfth force-sensitive resistor are both arranged on one of the elastic beams on the other side; the ninth force-sensitive resistor and the twelfth force-sensitive resistor are diagonally arranged in the electric bridge, and the tenth force-sensitive resistor and the eleventh force-sensitive resistor are diagonally arranged in the electric bridge.

5. The six-axis force sensor according to claim 4, characterized in that: The direction of the first torque rotates counterclockwise around the first axis, the plurality of force-sensitive resistors include a thirteenth force-sensitive resistor, a fourteenth force-sensitive resistor, a fifteenth force-sensitive resistor and a sixteenth force-sensitive resistor for measuring the first torque, the thirteenth force-sensitive resistor and the fourteenth force-sensitive resistor are arranged on one of the elastic beams on one side of the first axis, and the fifteenth force-sensitive resistor and the sixteenth force-sensitive resistor are arranged on one of the elastic beams on the other side; the thirteenth force-sensitive resistor and the fifteenth force-sensitive resistor are arranged diagonally in the bridge, and the fourteenth force-sensitive resistor and the sixteenth force-sensitive resistor are arranged diagonally in the bridge; The direction of the second torque rotates counterclockwise around the second axis, and the plurality of force-sensitive resistors further include a seventeenth force-sensitive resistor, an eighteenth force-sensitive resistor, a nineteenth force-sensitive resistor, and a twentieth force-sensitive resistor for measuring the second torque, the seventeenth force-sensitive resistor and the eighteenth force-sensitive resistor are arranged on one of the elastic beams on one side of the second axis, and the nineteenth force-sensitive resistor and the twentieth force-sensitive resistor are arranged on one of the elastic beams on the other side; the seventeenth force-sensitive resistor and the nineteenth force-sensitive resistor are arranged diagonally in the bridge, and the eighteenth force-sensitive resistor and the twentieth force-sensitive resistor are arranged diagonally in the bridge; The direction of the third torque rotates counterclockwise around the third axial direction, and the plurality of force-sensitive resistors include a twenty-first force-sensitive resistor, a twenty-second force-sensitive resistor, a twenty-third force-sensitive resistor and a twenty-fourth force-sensitive resistor for measuring the third torque, the twenty-first force-sensitive resistor and the twenty-fourth force-sensitive resistor are respectively arranged on a pair of the elastic beams on one side of the first axial direction or the second axial direction, and the twenty-second force-sensitive resistor and the twenty-third force-sensitive resistor are respectively arranged on a pair of the elastic beams on the other side; the twenty-first force-sensitive resistor and the twenty-third force-sensitive resistor are diagonally arranged in the bridge, and the twenty-second force-sensitive resistor and the twenty-fourth force-sensitive resistor are diagonally arranged in the bridge.

6. The six-axis force sensor according to claim 5, characterized in that: The eleventh force-sensitive resistor and the nineteenth force-sensitive resistor are the same force-sensitive resistor, and the twelfth force-sensitive resistor and the twentieth force-sensitive resistor are the same force-sensitive resistor.

7. The six-axis force sensor according to claim 4, characterized in that: The force-sensitive resistor for measuring the first force and the second force is arranged at a position of 1 / 6 to 1 / 2 of the elastic beam close to the supporting frame.

8. The six-axis force sensor according to claim 5, characterized in that: The force-sensitive resistor for measuring the third force, the first moment and the second moment is arranged at one end close to the force-bearing block and one end close to the supporting frame.

9. The six-axis force sensor according to claim 1, characterized in that: The force-sensitive resistors for measuring the third moment are all arranged at one end of the elastic beam close to the force-bearing block, or the force-sensitive resistors for measuring the third moment are all arranged at one end of the elastic beam close to the supporting frame; The force-sensitive resistor for measuring the third torque is arranged on the outside of an elastic beam away from another elastic beam in the same group of elastic members.

10. The six-axis force sensor according to claim 2, characterized in that: The six-axis force sensor further has a third axial direction intersecting with and perpendicular to the first plane. In the third axial direction, the thickness of the support frame is greater than the thickness of the force-bearing block and the elastic member.

11. A method for manufacturing a six-axis force sensor, characterized in that: Used to manufacture the six-axis force sensor according to any one of claims 1 to 10, the six-axis force sensor manufacturing method comprising: Providing a silicon wafer, and forming an oxide layer on a surface of one side of the silicon wafer; Performing patterning on the oxide layer to form a force-sensitive resistor pattern, and doping the silicon wafer at the position of the force-sensitive resistor pattern to form a force-sensitive resistor in the silicon wafer; The oxide layer is patterned to form an ohmic contact layer pattern, and the silicon wafer at the position of the ohmic contact layer pattern is doped to form an ohmic contact layer on the surface of the silicon wafer, wherein the ohmic contact layer is connected to the force-sensitive resistor; the ohmic contact layer is etched to form a plurality of ohmic contact regions corresponding to the force-sensitive resistors; and annealing is performed to activate the force-sensitive resistor and the ohmic contact region; Forming a wiring on a surface of one side of the silicon wafer having an ohmic contact area, wherein the wiring is connected to the force-sensitive resistor through the ohmic contact area; Patterning and etching the surface of the silicon wafer on one side away from the wiring to form a support frame to the thickness position of the force-bearing block and the elastic member; The surface of the silicon wafer on one side away from the wiring is patterned and etched in an area other than the supporting frame to form the force-bearing block and the elastic member.

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