WO2021051951A1 - 并联杆系多维力传感器结构 - Google Patents
并联杆系多维力传感器结构 Download PDFInfo
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- WO2021051951A1 WO2021051951A1 PCT/CN2020/099608 CN2020099608W WO2021051951A1 WO 2021051951 A1 WO2021051951 A1 WO 2021051951A1 CN 2020099608 W CN2020099608 W CN 2020099608W WO 2021051951 A1 WO2021051951 A1 WO 2021051951A1
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01L—MEASURING FORCE, STRESS, TORQUE, WORK, MECHANICAL POWER, MECHANICAL EFFICIENCY, OR FLUID PRESSURE
- G01L5/00—Apparatus for, or methods of, measuring force, work, mechanical power, or torque, specially adapted for specific purposes
- G01L5/16—Apparatus for, or methods of, measuring force, work, mechanical power, or torque, specially adapted for specific purposes for measuring several components of force
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01L—MEASURING FORCE, STRESS, TORQUE, WORK, MECHANICAL POWER, MECHANICAL EFFICIENCY, OR FLUID PRESSURE
- G01L1/00—Measuring force or stress, in general
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01L—MEASURING FORCE, STRESS, TORQUE, WORK, MECHANICAL POWER, MECHANICAL EFFICIENCY, OR FLUID PRESSURE
- G01L1/00—Measuring force or stress, in general
- G01L1/16—Measuring force or stress, in general using properties of piezoelectric devices
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01L—MEASURING FORCE, STRESS, TORQUE, WORK, MECHANICAL POWER, MECHANICAL EFFICIENCY, OR FLUID PRESSURE
- G01L1/00—Measuring force or stress, in general
- G01L1/20—Measuring force or stress, in general by measuring variations in ohmic resistance of solid materials or of electrically-conductive fluids; by making use of electrokinetic cells, i.e. liquid-containing cells wherein an electrical potential is produced or varied upon the application of stress
- G01L1/22—Measuring force or stress, in general by measuring variations in ohmic resistance of solid materials or of electrically-conductive fluids; by making use of electrokinetic cells, i.e. liquid-containing cells wherein an electrical potential is produced or varied upon the application of stress using resistance strain gauges
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01L—MEASURING FORCE, STRESS, TORQUE, WORK, MECHANICAL POWER, MECHANICAL EFFICIENCY, OR FLUID PRESSURE
- G01L5/00—Apparatus for, or methods of, measuring force, work, mechanical power, or torque, specially adapted for specific purposes
- G01L5/16—Apparatus for, or methods of, measuring force, work, mechanical power, or torque, specially adapted for specific purposes for measuring several components of force
- G01L5/165—Apparatus for, or methods of, measuring force, work, mechanical power, or torque, specially adapted for specific purposes for measuring several components of force using variations in capacitance
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01L—MEASURING FORCE, STRESS, TORQUE, WORK, MECHANICAL POWER, MECHANICAL EFFICIENCY, OR FLUID PRESSURE
- G01L5/00—Apparatus for, or methods of, measuring force, work, mechanical power, or torque, specially adapted for specific purposes
- G01L5/16—Apparatus for, or methods of, measuring force, work, mechanical power, or torque, specially adapted for specific purposes for measuring several components of force
- G01L5/167—Apparatus for, or methods of, measuring force, work, mechanical power, or torque, specially adapted for specific purposes for measuring several components of force using piezoelectric means
Definitions
- the invention belongs to the sensor measurement field and relates to a multi-dimensional force sensor structure.
- the multi-dimensional force sensor can detect the information of the force acting in space.
- a typical six-dimensional force sensor can obtain the 3 component forces and 3 moments formed by the force in the space coordinate system.
- the six-dimensional force sensor plays an important role, and the accuracy of the six-dimensional force obtained directly affects the system's work and control accuracy.
- the six-dimensional force sensor can be mainly divided into the overall elastic structure type, the Stewart parallel structure type, the piezoelectric crystal type, the frictionless guide type (air suspension, magnetic suspension), the flexible structure type, etc., among which the commercial small six-dimensional type
- the force sensor and MEMS field mainly adopt the integral elastic structure type, while the large six-dimensional force sensor mainly adopts the Stewart parallel structure type.
- the piezoelectric crystal type is mainly used in the field of high-frequency dynamic measurement.
- the frictionless guide type has very few applications due to its large structure and flexibility.
- the structure type is mainly used for the gripping of the mechanical finger end, and the accuracy is very low.
- the overall elastic structure generally uses a flexible hinge or a flexible flat structure instead of a physical hinge. Its accuracy is slightly higher, but the structural rigidity is small, and due to the coupling effect of the flexible body part, the accuracy generally does not exceed 2%.
- the Stewart parallel structure has greater rigidity, but due to the use of physical hinges, there is greater friction and its accuracy is very low.
- Piezoelectric crystal type generally adopts a plane multi-group arrangement, each group contains three wafers to measure three axial forces, the torque is calculated by multiple groups of force measurement, the force measurement frequency response is high, but the force measurement accuracy is low. And because of the charge drift, it is not suitable for static measurement.
- the existing six-dimensional force sensor has low accuracy and low rigidity, it is almost difficult to carry out large-scale commercial applications in the commercial field except for the low accuracy of the sensors required for grinding, polishing, clamping, and automobile crash tests. , And the above-mentioned applications such as grinding, polishing, and clamping can easily be better replaced with pneumatic and elastic components, so there are not many applications.
- the real commercial force control robots are almost always replaced by single-axis force sensors. However, each axis of the robot needs to use a single-axis force sensor, resulting in the structure of the robot. It is extremely complicated and costly, and it is extremely difficult to calculate the inertial force during high-speed motion.
- the multi-dimensional force sensor structure proposed by the present invention can basically be regarded as an ideal linear elastic body, and the coupling between dimensions is less than 1 ⁇ .
- the current main application areas of multidimensional force sensors are: force-controlled robots; minimally invasive surgical manipulators, medical auxiliary exercise equipment, walking robots, space manipulators, spatial docking force measuring devices; wind tunnel balances, automobile collision sensors, wheel hub force measuring devices , Jet engine force measuring device, propeller thrust force measuring device, deep sea docking force measuring device; mechanical processing force measuring device.
- the present invention aims to solve the problem of low accuracy in obtaining multi-dimensional force caused by the structure of the existing multi-dimensional force sensor. Furthermore, a parallel rod system multi-dimensional force sensor structure is proposed.
- Parallel rod system multi-dimensional force sensor structure including support platform, load platform, load platform and support platform are connected by parallel rod system, the external force of the load platform is completely transmitted to the support platform through the parallel rod system;
- a micro-displacement sensor for measuring the micro-displacement between the support platform and the load platform is arranged between the support platform and the load platform, and/or a strain gauge is arranged on the strain beam of the parallel rod system, and/or a piezoelectric crystal is used as the strain beam .
- the multidimensional force sensor structure includes integral type, welding and mechanical connection type, embedded type, press-fit type and suspension type.
- the multi-dimensional force sensor structure obtains the multi-dimensional force through the following steps:
- the global coordinate system is a coordinate system attached to the supporting platform
- the local coordinate system of the strain beam is a coordinate system attached to the strain beam;
- the local coordinate system of the micro-displacement sensor is a coordinate system attached to the micro-displacement sensor;
- the generalized force includes force and moment, and the generalized deformation displacement includes linear displacement and angular displacement;
- the generalized force When the multidimensional force is a six-dimensional force, the generalized force includes 3 forces and 3 moments, and the generalized deformation displacement includes 3 linear displacements and 3 angular displacements; when the multidimensional force is a plane three-dimensional force, the generalized force includes 2 forces and 1 Moment, generalized deformation displacement includes 2 linear displacements and 1 angular displacement;
- the coincidence point of the load platform and the corresponding local coordinate system origin is obtained in the local coordinate system
- the local deformation displacement along/around the measurement axis is called the observable measurement
- the deformation displacement of the load platform in the global coordinate system calculate all the local deformation displacements of the corresponding local coordinate origin of each strain beam in the local coordinate system, including three linear displacements and three angular displacements;
- the local generalized forces of all strain beams in the local coordinate system are translated to the origin of the global coordinate system according to the vector transformation relationship between the local coordinate system and the global coordinate system and summed to obtain the multi-dimensional force of the multi-dimensional force sensor.
- the load platform produces displacement under the global coordinate system oxyz under the action of external force among them, Is the linear displacement in the local coordinate system o i x i y i z i; Is the angular displacement in the local coordinate system o i x i y i z i;
- the origin of the local coordinate system is the center of the contact surface between the strain beam and the supporting platform Establish the local coordinate system of the supporting platform respectively
- the strain beam produces deformation and displacement under the force of among them Is the linear displacement in the local coordinate system o i x i y i z i; Is the angular displacement in the local coordinate system o i x i y i z i;
- the coincidence point of the load platform and the corresponding local coordinate system origin is obtained in the local coordinate system
- the local deformation displacement along the measurement axis is called the observable measurement; according to the space vector transformation, the local displacement in the partial local coordinate system can be used to observe the measurement and calculate the displacement of the load platform under the global coordinate system oxyz Then calculate the local displacement of all strain beams in the local coordinate system
- the local generalized force of all strained beams can be obtained among them Is the force in the local coordinate system o i x i y i z i, Is the moment in the local coordinate system o i x i y i z i;
- the flexibility matrix of the strain beam at the local coordinate origin o i as Obtain the flexibility matrix of the strain beam at the origin o i of the local coordinate using the method of finite element analysis or the test method Or, for a straight-bar strain beam with uniform cross-section, Euler, Timoshenko or higher-order modern beam theories are used, and the flexibility matrix is determined according to the force-deformation relationship of the strain beam
- the load platform and support platform regard the load platform and support platform as a semi-elastic space; define the flexibility matrix of the load platform at the local coordinate origin o i as Define the local coordinate origin of the supporting platform on the supporting platform
- the flexibility matrix is Use finite element analysis method or test method to obtain flexibility matrix average with Or, use Boussinesq, Mindlin or modern high-order semi-elastic space theory to derive flexible matrix with Approximate value of
- the flexibility matrix corresponding to the supporting platform Moving to point o i , the sum of the elastic deformation part of the load platform and the support platform at the local coordinate o i and the flexibility matrix of the strain beam is: Represents from the local coordinate system To the space vector transformation matrix of the local coordinate system o i x i y i z i ; and then obtain the inverse matrix of the flexibility and matrix, that is, the stiffness matrix
- the external generalized force borne by the load platform in the global coordinate system is The generalized displacement of the load platform in the global coordinate system when subjected to external forces is
- Figure 1 is a schematic diagram of the structure of a multidimensional force (six-dimensional force) sensor
- Figure 2 is a schematic diagram of a local coordinate system
- Figure 3 is a schematic diagram of the process of determining the relationship between each local coordinate system and the global coordinate system
- Figure 4 is a schematic diagram of deformation of a strain beam under force in a local coordinate system
- Figure 5 is a schematic diagram showing that the strain beam can be any shape strain beam
- Figure 6 is a schematic diagram of the force on the rigid plane of the elastic half-space
- Figure 7 is a schematic diagram of part of the contact surface detached during the force process of the bolt connection
- Figure 8 is a plane symmetrical 8-strain beam multi-dimensional force sensor
- Figure 9 is a typical strain gauge processing circuit
- Figure 10 is a schematic diagram of some classic planar three-dimensional force sensors
- Figure 11 is a schematic diagram of the structure of a typical spatial six-dimensional force sensor
- Figure 12 is a schematic diagram of the structure and processing sequence of some typical integral spatial six-dimensional force sensors
- Figure 13 is a schematic diagram of some typical integral spatial six-dimensional force sensors
- Figure 14 is a schematic diagram of some typical welded and mechanically connected six-dimensional force sensors
- Figure 15 is a schematic diagram of some typical planar embedded connection methods
- Figure 16 is a schematic diagram of some typical embedded spatial six-dimensional force sensors
- Figure 17 is an example of the press-fitting method of the press-fit structure and the placement position of the sensor
- Figure 18 shows the embedding and press-fitting structure of the pressure block strain beam in the case of the whole shell
- Figure 19 shows the embedding and press-fitting structure of the pressure block strain beam in the case of a split shell
- Figure 20 is a method of combining a tensile strain beam with a press-fit structure
- Figure 21 shows the method of measuring the relative displacement of the load platform and the support platform using a capacitive sensor in a press-fit structure
- Figure 22 is a schematic structural diagram of a typical press-fit space six-dimensional force sensor
- Figure 23 is a schematic diagram of the connection of the upper and lower support platforms of the press-fit structure
- Figure 24 is a schematic diagram of 8-beam and 12-beam press-fit structure load platforms
- Figure 25 shows three types of multi-dimensional force sensors with suspension structures.
- Loading platform Loading platform, Supporting platform: Supporting platform, Strain gauge: Strain gauge, Fixed on supporting platform: Fixed on the supporting platform, Initial state: Initial state, Rotation about x/y/z: Rotation about x/y/z axis , Transformation along x/y/z: move along the x/y/z axis, Connection with loading platform: connect to the load platform, Displacement of loading platform: displacement of the load platform, Displacement of o in global coordinate system: o point in global coordinate the system displacement, displacement of oi in global coordinate system : o i displacement in the global coordinate system, displacement of oi in local coordinate system : o i displacements in the local coordinate system, bending deformation by F: bent from F due to Deformation, Shear deformation by F: Shear deformation caused by F, View A: View A, Elastic half-space: Elastic half-space, Rigid plane: Rigid plane, Capacitive sensor: Capacitive sensor, Piezoelectric crystal:
- This embodiment is a parallel rod system multi-dimensional force sensor structure, including a support platform and a load platform.
- the load platform and the support platform are connected by a parallel rod system.
- Each rod of the parallel rod system is set as an independent strain beam on the load platform and Between the supporting platforms, the external force of the load platform is completely transmitted to the supporting platform by the parallel rod system;
- the parallel rod system can be composed of one to any number of strain beams;
- a micro-displacement sensor for measuring the micro-displacement between the support platform and the load platform is arranged between the support platform and the load platform, and/or a strain gauge is arranged on the strain beam of the parallel rod system, and/or a piezoelectric crystal is used as the strain beam .
- the multi-dimensional force of the load platform can be calculated through the deformation of the strain beam or the micro-displacement between the load platform and the support platform;
- Deformation of the strain beam Paste a strain gauge on the strain beam or use a piezoelectric crystal as the strain beam, and calculate the strain beam deformation in the local coordinate system through the strain measured by the strain gauge or the charge change measured by the topping crystal.
- the deformation can be further used to calculate the deformation displacement of the load platform, and then obtain the multi-dimensional force.
- a micro-displacement sensor is arranged between the load platform and the support platform to measure the displacement between the two, and the load is calculated by the measurement of the micro-displacement sensor in its own local coordinate system The platform is deformed and displaced, and then multi-dimensional forces are obtained.
- the multi-dimensional force calculation method adopted is to obtain the corresponding micro-displacement sensor and the strain beam through the micro-displacement sensor, strain gauge, and piezoelectric crystal to measure the micro-displacement of the sensitive axis under its local coordinate system.
- the micro-displacement is called the observable measurement and is passed
- the space vector transformation method obtains the coordinated relationship equation group of the micro-displacement of the load platform and the micro-displacement of the local coordinate system, and establishes the load platform micro-displacement solving equation set by extracting the specific equations from the coordinated relationship equation group, and solves it by using the observables obtained above
- the micro-displacement of the load platform is solved by equations, and finally the micro-displacement of the load platform in the global coordinate system is obtained; the micro-displacement of the load platform is used to further solve all the local micro-displacements of each strain beam, and further solve the local micro-displacement of each strain beam
- the structure of multi-dimensional force sensor includes integral type, welding and mechanical connection type, embedded type, press-fit type and suspension type;
- the integral type is: an integrated structure of load platform, support platform and strain beam, that is, a whole piece of material is manufactured by machining methods (such as milling, etc.), and the force between the load platform and the support platform is one piece
- the transmission is completed in the whole material; its purpose is to maintain the rigidity of all parts in the force transmission path when the supporting platform is stressed and the strain beam is deformed, so as to avoid sudden changes in the rigidity of some parts.
- the welding and mechanical connection type is: the strain beam is connected to the load platform and the support platform by welding or mechanical connection structure, and the force transmission between the load platform and the support platform is transmitted through welding or other mechanical connection structures.
- the welding part and other contact parts should basically keep in contact during the stress process; the purpose is to keep the contact stiffness of the contact surface between the strain beam and the load platform and the support platform basically unchanged when the support platform is stressed and the strain beam is deformed. change.
- the embedded structure is: the strain beam is connected to the load platform and the support platform with an embedded structure, the force transmission between the load platform and the support platform is transmitted through the embedded structure, and the pressure assembly method is used to connect the load platform and the support platform.
- the embedded end is pressed into the corresponding embedded hole, or the embedded end and the embedded hole are connected through other media, so that all contact surfaces are prestressed, and all contact surfaces still maintain a certain prestress during the stress process, and then Ensure that all contact surfaces will not detach, that is: the embedded pre-tightening structure is used to avoid the separation of the contact surface of the strain beam and the platform during the load process of the sensor; the purpose is that when the load platform is stressed and the strain beam is deformed, the strain beam and the load platform The contact stiffness of the contact surface between and the supporting platform remains unchanged.
- the press-fitting type is: the strain beam adopts a press-fitting structure to be connected to the load platform and the support platform respectively, and the force transmission between the load platform and the support platform is transmitted through the press-fitting structure;
- the type structure means that the contact surfaces of both ends of the strain beam with the load platform and the support platform are maintained at a certain pre-compression stress through the pressure assembly method, and all the contact surfaces still maintain a certain pre-compression stress during the stress process, thereby ensuring the contact surface
- the press-fit structure is adopted to avoid the separation of the contact surface of the strain beam and the platform during the force process of the sensor; the purpose is to support the platform when the strain beam deforms and the strain beam and the load The contact stiffness of the contact surface between the platform and the supporting platform remains unchanged.
- each strain beam is a thin suspension line, which is connected to the load platform and the supporting platform respectively. All the suspension line strain beams are applied with a certain pretension stress, and The tensile stress is maintained during the process; the purpose is to maintain the rigidity of each part including the suspension strain beam when the load platform is stressed and the suspension strain beam deforms.
- the solution method of the multidimensional force sensor of the present invention is as follows:
- the main body of the symbol represents a space vector
- Q represents a generalized force including force and moment
- F represents a force
- M represents a moment
- ⁇ represents a generalized deformation displacement including linear displacement and angular displacement
- ⁇ D represents linear deformation displacement
- ⁇ represents angular deformation displacement
- r represents the distance between the origin of the local coordinate system and the origin of the global coordinate system in the global coordinate system
- ⁇ represents the rotation angle of the local coordinate system around the three axes of the global coordinate system
- the upper corner in the upper left corner represents the coordinate system.
- the upper corner in the upper left corner is marked as g to indicate that the corresponding parameter is a parameter in the global coordinate system oxyz;
- the upper corner in the upper left corner is marked as i to indicate that the corresponding parameter is the strain beam local coordinate system o
- the upper corner in the upper left corner is marked with j to indicate that the corresponding parameter is the parameter under the local coordinate system of the displacement sensor o j x j y j z j ;
- the subscript in the lower left corner represents the point where the vector acts.
- the subscript in the lower left corner is marked as o, which means that the corresponding vector acts on the origin o of the global coordinate system oxyz;
- the subscript in the lower left corner is marked as o i /o j , which means the corresponding vector acts on beam strain / displacement sensor local coordinate system o i x i y i z i / o j x j y j z j origin o i / o j;
- the upper corner of the upper right corner marked with i/j means that the applicator is the i-th strain beam or the j-th sensor; g or blank means the global quantity, that is, the applicator is the external force on the load platform;
- the subscript in the lower right corner represents the direction of the vector
- the subscript in the lower right corner is marked as x, which means along the x axis
- the subscript in the lower right corner is marked as y, which means along the y-axis
- the lower corner is marked as z, which means along the z-axis.
- the subscripts marked with F and M mean that the variables are caused by force or moment
- the subscript blanks in the lower right corner indicate the vector formed by the xyz axis.
- E.g Represents the i-th beam, under the global coordinate system oxyz (ie g), the force F acting on the o i point along the x direction of the global coordinate system; Represents the i-th beam, acting on point o i under the local coordinate system i (ie o i x i y i z i ), and the linear displacement along the z i direction of the local coordinate system caused by the action of the torque M ⁇ D.
- micro-displacement measurement method of the load platform of the multi-dimensional force sensor is the basis of the multi-dimensional force acquisition method, first explain the multi-dimensional force acquisition method of the multi-dimensional force sensor using the parallel link system;
- the load platform and the support platform are regarded as pseudo-rigid bodies.
- all the deformed parts of the external force and the deformed part of each connected strain beam can be isolated, and all the deformed parts of the support force and each connection can be isolated on the support platform.
- the deformation part of the strain beam is isolated; through the beam theory of elastic mechanics and the force space transformation theory of theoretical mechanics, the deformation displacement and force of each strain beam are connected with the displacement and force of the load platform as a pseudo-rigid body. Strain or piezoelectric changes or micro-displacement changes between the load platform and the support platform obtain the external force on the load platform.
- the calculation method is:
- the coordinate system is fixedly connected to the supporting platform and does not move, but for display convenience, the origin of the coordinate system is generally placed at the center o of the force-bearing part of the load platform.
- the global coordinate system in the figure is oxyz, abbreviated as xyz; the y-axis is perpendicular to the x-axis, and the z-axis is perpendicular to the plane y-x;
- the local coordinate system in the figure is o i x i y i z i , abbreviated as x i y i z i , where i represents the i-th beam; the strain beam and load
- the center of the contact surface of the platform is the origin o i of the local coordinate system; as shown in Figure 2, the center line of the strain beam is the local coordinate system x i axis, the y i axis is perpendicular to the x i axis, and the y i axis is in the end face of the strain beam,
- the z i axis is perpendicular to the plane y i -x i .
- each local coordinate system and the global coordinate system can be represented by three rotation angles and three translation distances, denoted as with As shown in Figure 3, Figure 3 shows the process of determining the relationship between each local coordinate system and the global coordinate system, that is, the method of establishing the beam local coordinate system; that is: the initial state is that the local coordinate system coincides with the global coordinate system.
- the strain beam rotates along x relative to the initial position Then rotate along y Then rotate along z Then translate along the xyz axis Then connect the two ends of the strain beam to the load platform and the support platform respectively; when the load platform is displaced by the force, the coincidence point of the load platform with the origin of the global coordinate system moves from o to o′; the strain beam and the local coordinate system The coincidence point of the origin o i moves to o i ′.
- This method of establishing a local coordinate system as Coordinate Ma;
- the deformation diagram of the strain beam under force in the local coordinate system is shown in Figure 4; when Euler beams are used (Timoshenko beams or other high-order beams can also be used), according to the force relationship of the strain beams:
- E is the elastic modulus
- G is the shear modulus
- l i is the length of the strain beam
- a i is the cross-sectional area of the strain beam
- the representation of the space vector symbol above is the same. The subscript in the lower right corner represents the direction of the vector.
- the subscript in the lower right corner is marked as x to indicate along the x axis
- the subscript in the lower right corner is marked as y to indicate along the y axis.
- the lower corner in the lower right corner is marked with z to indicate that it is along the z axis; the presence of other parameters in the lower corner in the lower right corner indicates the amount of the corresponding parameter on the corresponding axis.
- the lower corner in the lower right corner is marked as Mz, which means it is on z due to M ⁇ The amount.
- the flexibility matrix of the strain beam at the local coordinate origin o i is defined as:
- the strain beam can be any shape strain beam, as shown in Figure 5.
- the flexibility matrix of the strain beam at the origin o i of the local coordinates can be obtained by using finite element or test methods; for straight-rod strain beams of constant cross-section, the strain beam can also be subjected to the aforementioned force-deformation relationship, and further based on Euler-Bernoulli beam theory writes the flexibility matrix (which can also be obtained from Timoshenko beam and other modern beam theories) as:
- the schematic diagram of the rigid plane force of the elastic half space is shown in Figure 6.
- the load platform and the support platform can be regarded as the elastic half space, and the flexibility matrix of the connection with the strain beam can be passed through the elastic half space.
- the force, displacement and deformation relationship of the rigid plane is obtained;
- the flexibility matrix of the load platform at the local coordinate origin o i is defined as:
- the origin of the local coordinate system is the center of the contact surface between the strain beam and the supporting platform Establish the local coordinate system of the supporting platform (similar to the local coordinate system established at the center of the contact surface between the strain beam and the load platform); the supporting platform is at the origin of the local coordinate of the supporting platform
- the flexibility matrix is defined as:
- the finite element or test method can be used to obtain the average flexibility matrix with
- Flexibility matrix corresponding to strain beam Flexibility matrix corresponding to the load platform Flexibility matrix corresponding to the supporting platform Both need to be processed on point o i and summed; therefore, the flexibility matrix corresponding to the support platform Move to point o i ;
- Rot() refers to spatial rotation transformation; its inverse transformation is:
- T i g represents the spatial transformation matrix from the coordinate system o i x i y i z i (i) to the coordinate system oxyz (g), the angle between the coordinate system i and the coordinate system g is ⁇ i , and the distance between the origins is r i ;
- the external force borne by the load platform in the global coordinate system is The displacement of the load platform in the global coordinate system when subjected to external forces is
- the stiffness matrix is only related to the actual structure, all the structural parameters have been obtained in advance.
- the six-direction micro-displacement of the load platform under the action of the external force is measured, the six components of the external load force can be obtained.
- the size namely: as long as the micro-displacement measurement sensor arranged between the support platform and the load platform, and/or the strain gauge pasted on the strain beam, and/or the piezoelectric crystal as the strain beam, the load platform is measured
- the micro-displacement in six directions under the action of external force can obtain the multi-dimensional force obtained by the multi-dimensional force sensor, including three-dimensional force, six-dimensional force and other dimensional force.
- the structure of the present invention there is no multi-dimensional force sensor with the structure of the present invention in this field. It is determined by the solution method of the existing multi-dimensional force sensor.
- the current solution method of the multi-dimensional force sensor is that the six-dimensional force must be determined by the structure.
- the strain of these weak parts directly presents a linear relationship, ignoring all the cross-coupling in the transmission process, or the structure is considered to be a pure rigid body, connected by frictionless hinges, ignoring all the deformation and friction of the structure, so
- the structure is either too complex, with a large number of parallel-series structures, or too simple, using a hinge structure to decouple all forces.
- the multi-dimensional force sensor structure in the present invention cannot be solved by the traditional solving method.
- the structural rigidity of all parts of the entire force transmission path needs to remain basically unchanged.
- the contact surface of two parts in common welding and bolt connection structures is prone to partial contact surface separation during the entire force process, which leads to sudden changes in the contact stiffness of the contact surface and reduces the accuracy of the multidimensional force measurement results.
- the invention guarantees the invariance of the structural rigidity on the force transmission path through a variety of structural design schemes.
- Multi-dimensional mechanical sensors can be divided into two-dimensional force (plane two-dimensional force or one-dimensional force plus one-dimensional moment) and three-dimensional force (plane two-dimensional force plus in-plane torque, or three-dimensional force along three coordinate axes, or around three Coordinate axis torque), 4-dimensional force, 5-dimensional force and 6-dimensional force sensor.
- plane 3-dimensional force plane 2-dimensional force plus in-plane torque
- stereo 6-dimensional force sensor are the most common sensors, and other sensors can be obtained by ignoring certain dimensional forces (torques) on this basis.
- the multi-dimensional force sensor of the present invention is composed of multiple strain beams with parallel structures, and can be divided into an integral structure, a welding machine and a mechanical connection structure, an embedded structure and a press-fit structure.
- the multi-dimensional mechanical sensor structure of the present invention will be described in conjunction with the drawings.
- Each structure has two forms of plane three-dimensional force and three-dimensional six-dimensional force.
- the strain beam and the foundation platform are connected together by bolts.
- the contact between the strain beam and the foundation platform The surface will be deformed.
- the deformation is relatively large, the original contact surface will be partly out of contact, which will cause a sudden change in the contact stiffness, and a sudden change in the displacement transmission of the strain near the contact surface, which will eventually cause the calculated multidimensional force result to be inaccurate; this result
- the beneficial result of this limitation is to avoid the occurrence of sudden changes in the stiffness of certain parts of the force transmission path, thereby effectively ensuring the calculation accuracy of the micro-displacement of the load platform, and ultimately ensuring the accuracy of the multidimensional force sensor.
- Integral structure means that the entire sensor (mainly including strain beam, load platform and support platform) except for auxiliary parts (housing, external adapters, etc.) is processed from a single piece of work.
- the advantage of this structure is that the strain beam is a uniform and continuous whole at the connection between the support platform and the load platform, and there will be no sudden changes in stiffness, and the measurement accuracy is high.
- This structure is particularly suitable for small and medium-sized, micro- and MEMS-structured multi-dimensional force sensors with a load of several hundred kilograms or less, and is used in force-controlled robots, collaborative robots, endoscopic minimally invasive surgical robots, bionic manipulators, and other small and medium-sized multi-dimensional force measuring devices.
- the plane structure three-dimensional force sensor means that the load platform, the support platform and the beam structure are all arranged in a plane or multiple planes parallel to each other.
- the structural relationship can be projected on a plane, and the force that can be characterized includes two projections in the plane.
- the force and a moment are shown in Figure 8.
- strain gauges pasted on the four faces of the strain beam can be used to measure the average tensile/compressive strain (stress) of the strain beam along the axial direction x i of the strain beam.
- E is the external reference voltage
- e is the measured voltage.
- the frequency method and other methods can also be used to measure the strain of the strain gauge.
- the strain gauge can be measured by a general differential bridge, or it can directly measure the strain of each strain gauge, and then process it through a digital circuit, and then measure the strain sum of the strain gauge 1 and the strain gauge 3 or the strain gauge 2 and the strain gauge The sum of 4, or the sum of all 4 strain gauges 1, 2, 3, and 4. In this way, the bending stress can be ignored, and only the tensile/compressive stress of the strain beam can be obtained, and then the tensile/compressive stress of the strain beam along the axial direction x i can be obtained.
- Figures 10(a) to 10(f) are typical integral planar three-dimensional force sensors.
- the strain beams include constant-section strain beams and variable-section strain beams.
- the three-dimensional six-dimensional force sensor refers to the three-dimensional structure of the load platform, support platform and beam structure.
- the force that can be characterized includes three forces and three moments; as shown in Figure 11 (a) and Figure 11 (b);
- Fig. 12(a) and Fig. 12(b) respectively show the processing process of the integrated three-dimensional six-dimensional force sensor structure.
- the integrated structure includes, but is not limited to, the structure shown in FIG. 11(a) and FIG. 11(b), and may also be other forms such as the structure shown in FIG. 13(a) to FIG. 13(f).
- the welding and mechanical connection structure adopts the method of separately processing the support platform, load platform and strain beam and then assemble the three together to complete the entire sensor body structure.
- the welding and mechanical connection structures include, but are not limited to, the structures shown in Figs. 14(a) and 14(b), and may also be other types of structures shown in Figs. 14(c) to 13(d).
- the structural size of the welded or bolted joint should be larger than the cross-sectional size of the strain beam to ensure that the structural rigidity of the welded or bolted joint is greater than the structural rigidity of the strained beam.
- the pre-tightening force of the bolt connection should be large enough to ensure that the contact surface will not be partially separated during the stress process.
- the feature of the embedded structure is that it can use lower rigidity strain beam materials and higher rigidity support platform and load platform structure.
- the support platform and load platform use steel, titanium alloy and other materials
- the strain beam uses rubber, bakelite, Plastics and other materials can ensure that large strain beam deformations can be generated under small stress conditions, which are more suitable for small force measurement.
- the planar three-dimensional force sensor structure includes but is not limited to the structure shown in FIG. 15(a).
- the embedding adopts an extrusion pre-tensioning method, as shown in Figure 15(b), the two ends of the strain beam are made of relatively large heads, and the corresponding ones are made on the load platform and the support platform.
- the size of the embedded hole is slightly smaller than the head of the strain beam, and the head of the strain beam is squeezed into the embedded holes on the load platform and the support platform by mechanical extrusion.
- the purpose is to generate prestress on the contact surface between the head and the platform, so that the contact surface will not partly fall out of contact during the measurement process, so that the contact stiffness will not change.
- Embedded can also adopt other forms, as shown in Figure 15(c) for pre-tightening of the wedge.
- the top of the wedge pre-tightening method can be pre-tightened by a pressure plate, as shown in Figure 15(d), but it is not necessary to adopt this form in Dang Rang.
- This kind of pressure plate pre-tightening is not only suitable for wedge pre-tightening type, but also applicable to other pre-tightening methods such as extrusion type;
- Embedding can also take other forms, as shown in Figure 15(e), the injection connection method, that is, the connection is made by injecting a solidifiable liquid, such as injecting liquid metal, resin, etc.
- the embedded end bolt connection method can also be adopted, that is, the connection is made by squeezing or tightening the embedded end with bolts, as shown in Fig. 15(g) and Fig. 15(h).
- This type of connection is convenient for brokering, but it is prone to problems with low contact stiffness and partial separation of the contact surface. It is necessary to carefully consider the load force and appropriately increase the bolt diameter.
- the embedding method of the three-dimensional six-dimensional force sensor structure is the same, except that the structure is a three-dimensional structure, as shown in Figure 16 (a) to Figure 16 (c).
- the present invention includes but is not limited to these forms.
- the feature of the press-fit structure is to press-fit the thin elastic beam with the load platform and the support platform through pre-tightening force. All the elastic beams are not on the same plane at the same time.
- the pre-tightening force is applied during assembly to make the elastic beam pre-tensioned During the measurement, the pressure is maintained during the measurement process to prevent the elastic beam from detaching from the load platform and the support platform.
- the strain beam can be made of piezoelectric crystal, measured by piezoelectric effect, or other materials can be used by pasting strain gauges on the strain beam or installing a micro displacement sensor on the strain beam, or installing a micro displacement sensor between the load platform and the support platform Take measurements.
- Figure 17(a) shows the direct placement of a strain beam between the load platform and the support platform
- Figure 17(b) shows the connection between the load platform and the support platform.
- Strain beams are arranged inside the parts between the middle parts.
- Figure 17(c) is equipped with capacitive sensors at the upper and lower ends of the strain beams.
- the integral pre-tightening type planar three-dimensional force sensor means that the support platform and the load platform are respectively an integral structure.
- the platform needs to be expanded by applying external force such as a press. Then put in the strain beam (located at the four corners in Figure 18), and after the external force is removed, the platform rebounds, and then the corresponding strain beam is pre-tightened.
- the present invention includes, but is not limited to, the integral pre-tensioned planar three-dimensional force sensor shown in FIG. 18.
- the three-dimensional six-dimensional force sensor can also be preloaded in the same way.
- Supporting platform pre-tightening type
- the support platform pre-tightening type planar three-dimensional force sensor
- the support platform pre-tightening type refers to the support platform is divided into separate structures, during the assembly process, the different parts of the support platform are connected by bolts or welding or other connection methods. When it is integrated, the elastic beam will be compressed and pre-tightened.
- the beam pre-tightening type refers to the use of a pre-tensioned beam that can be tensioned (generally a metal beam) to a thin-walled elastic beam (generally Non-metallic beams are used for pre-tensioning.
- the pre-tensioned beams can be placed outside the thin-walled elastic beams ( Figure 20(a)) or in the middle of the thin-walled elastic beams ( Figure 20(b)).
- the characteristic of this kind of structure is that in the process of sensor measurement, the force of the pre-tensioned beam should also be considered in the calculation.
- the force calculation of the multidimensional force sensor can be calculated by measuring the force of an elastic beam, or by measuring the micro-displacement between the load platform and the supporting platform.
- the micro-displacement between the load platform and the supporting platform can be measured by multiple micro-displacement sensors (capacitance, inductance, eddy current, triangular light, confocal light, astigmatism, etc.).
- capacitive sensor in the figure as an example, which can be arranged in The outside of the elastic beam can also be arranged on the elastic beam, as shown in Figure 21 (a) and Figure 21 (b).
- the change in the amount of charge generated by the piezoelectric crystal can be directly used for calculation.
- Strain gauges (electrical, optical) can also be arranged on thin-walled strain beams and pre-tensioned beams, which can be calculated by measuring strain.
- the arrangement of the three-dimensional six-dimensional force is basically similar to that of the plane. All elastic beams are not arranged in the same plane at the same time. Two methods of platform pretension and pretension beam pretension can also be used. There are three ways of micro-displacement between supporting platforms, piezoelectric crystal measurement and strain gage arrangement.
- Figure 22 is a schematic diagram of the arrangement and pre-tensioning of the piezoelectric crystal.
- the piezoelectric crystal in the figure can be regarded as a strain beam.
- the six-dimensional force can be calculated directly according to the change in the charge of the piezoelectric crystal; the piezoelectric crystal in the figure The crystal can also be replaced with other materials.
- a micro-displacement sensor needs to be arranged between the load platform and the support platform, and the six-dimensional force is calculated by the change of the micro-displacement sensor; the support platform in this figure is divided into upper and lower parts, in the specific structure Need to be connected as one;
- Figure 23 is a schematic diagram of the split structure and connection of the supporting platform.
- the structure in this figure can be used to connect together, and at the same time, the corresponding variable beam can be pre-tightened.
- Figure 24(a) and Figure 24(b) are schematic diagrams of the load platform structure of 8 press-fitted strain beams and 12 press-fitted strain beams respectively. In this figure, only the load platform and strain beam structure are shown.
- the supporting platform structure can refer to Figure 22 above.
- Figure 25 shows three types of suspension-type multi-dimensional force sensors.
- Figure 25(a) shows a planar structure, which uses clamping and pre-tightening structures to tighten all suspension wires.
- Figure 25(b) shows an embedded planar structure.
- the suspension wire and the embedded blocks at both ends are an integrated structure, and the suspension wire is fixed and pre-tightened by embedded.
- Figure 25(c) is a three-dimensional structure.
- the support platform is divided into an upper support platform and a lower support platform.
- the supporting platforms need to be connected by a fixed structure and pre-tighten the suspension wires.
- the advantage of this kind of structure is that the suspension strain beam can be very thin, and the supporting platform and the load platform can be regarded as pseudo rigid bodies that are very close to the ideal rigid body.
- the structural bearing capacity is small, but the multidimensional force measurement accuracy is extremely high.
- the present invention includes, but is not limited to, the multi-dimensional force sensor structure shown in FIGS. 8 to 25, which may be a form in which all structures in the embodiment of the present invention are combined with each other or in other forms.
Abstract
一种并联杆系多维力传感器结构，涉及传感器测量领域，包括支撑平台和负载平台，负载平台和支撑平台通过并联杆系连接，负载平台所受的外力完全通过并联杆系传递到支撑平台上；在支撑平台和负载平台之间布置有测量两者之间微位移的微位移传感器，和/或，在并联杆系的应变梁上设置有应变片，和/或，采用压电晶体作为应变梁；该多维力传感器结构能够解决现有的多维力传感器获取多维力精度低的问题。
Description
本发明属于传感器测量领域，涉及一种多维力传感器结构。
多维力传感器能检测力在空间作用的信息，其中典型的六维力传感器可以获取作用力在空间坐标系所形成的3个分力和3个力矩。在航空航天领域、机器人领域等，六维力传感器发挥着重要作用，其获得的六维力的准确性直接影响着系统的工作和控制精度。
从六维力传感器结构上分析，六维力传感器主要可以分为整体弹性结构式，Stewart并联结构式，压电晶体式、无摩擦导轨式(气浮、磁悬浮)，柔性结构式等，其中商用小型六维力传感器和MEMS领域主要采用整体弹性结构式，而大型六维力传感器主要采用Stewart并联结构式，压电晶体式主要用于高频动态测量领域，无摩擦导轨式由于结构体积太大应用极少，柔性结构式主要用于机械手指端抓取，精度很低。
整体弹性结构式一般采用柔性铰链或柔性平板结构代替物理铰链，其精度稍高，但结构刚度很小，且由于柔性体部分的耦合影响，精度一般不超过2％。Stewart并联结构式结构刚度较大，但由于采用了物理铰链，有较大的摩擦力影响，其精度很低。压电晶体式一般采用平面多组布置，每一组包含三个晶片分别测量三个轴向力，转矩由多组测力进行推算，测力频响较高，但测力精度较低，且由于电荷漂移不适合静态测量。
由于现有的六维力传感器精度很低且其刚度很小，在商用领域除打磨、抛光、夹持、汽车碰撞试验等所需传感器精度很低的情况外，几乎很难进行大规模商业应用，而上述的打磨、抛光、夹持等应用场合可以很容易地用气动、弹性等元器件进行更好的替代，因此应用也不多。以需要高精度测力的协作力控机器人为例，真正的商品化力控机器人几乎都采用单轴力传感器进行替代，但由于机器人的每一个轴都需要采用一个单轴力传感器，造成机器人结构极其复杂，成本极高，且造成高速运动时惯性力解算极其困难。以需要高精度测力的医疗手术机器人为例，几乎所有操作医生均认为手术过程中的力反馈对操作者影响很大，但由于现有六维力传感器精度太低，所有真正商用化的手术机器人都放弃了采用六维力传感器而只采用图像传感器。
由于传统多维力传感器解算方法存在问题，导致传统多维力传感器结构设计不完善，存在很大的维间耦合，一般维间耦合大于2％，基本上精度低问题主要是是由于维间耦合导致。本发明所提出的多维力传感器结构基本上可视为理想线弹性体，维间耦合小于1‰。
多维力传感器当前的主要应用领域为：力控机器人；微创手术机械臂，医疗辅助锻炼 设备，步行机器人，空间机械臂，空间对接测力装置；风洞天平，汽车碰撞传感器，轮毂测力装置，喷射发动机测力装置，螺旋桨推力测力装置，深海对接测力装置；机械加工测力装置。
发明内容
本发明为了解决现有的多维力传感器的结构导致其获取多维力精度低的问题。进而提出一种并联杆系多维力传感器结构。
并联杆系多维力传感器结构，包括支撑平台、负载平台，负载平台和支撑平台通过并联杆系连接，负载平台所受的外力完全通过并联杆系传递到支撑平台上；
在支撑平台和负载平台之间布置有测量两者之间微位移的微位移传感器，和/或，在并联杆系的应变梁上设置有应变片，和/或，采用压电晶体作为应变梁。
进一步地，所述多维力传感器结构包括整体式，焊接及机械连接式，嵌入式，压装式和悬线式类型。
进一步地，所述多维力传感器结构通过以下步骤获取多维力：
全局坐标系统为附着于支撑平台上的坐标系统；
应变梁局部坐标系统为附着于应变梁上的坐标系统；
微位移传感器局部坐标系统为附着于微位移传感器上的坐标系统；
根据空间矢量变换法则建立局部坐标系统和全局坐标系统间的矢量变换关系矩阵，包括广义力变换关系、广义变形位移变换关系和位移传感器变换关系；
所述的广义力包括力和力矩，所述广义变形位移包括直线位移和转角位移；
多维力为六维力时，广义力包括3个力和3个力矩，广义变形位移包括3个直线位移和3个转角位移；多维力为平面三维力时，广义力包括2个力和1个力矩，广义变形位移包括2个直线位移和1个转角位移；
根据理论力学、材料力学和弹性力学建立局部坐标系统下的应变梁、支撑平台及负载平台的变形和受力的关系矩阵，即局部刚度矩阵和局部柔度矩阵；
根据应变梁上粘贴的应变片，或/和压电晶体作为应变梁，或/和负载平台和支撑平台之间设置的位移传感器，得到负载平台与相应局部坐标系原点重合点在局部坐标系下沿/绕测量轴线的局部变形位移，称为可观测量；
根据所述负载平台与相应局部坐标系原点重合点在局部坐标系沿/绕测量轴线的局部变形位移计算负载平台在全局坐标系统下的变形位移，包括三个直线位移和三个转角位移；
根据负载平台在全局坐标系统下的变形位移计算每个应变梁相应局部坐标原点在局部坐标系统下的所有局部变形位移，包括三个直线位移和三个转角位移；
根据每个应变梁在局部坐标系统下的局部变形位移计算每个应变梁在局部坐标系统下的局部广义力，包括三个力和三个转矩；
将所有应变梁在局部坐标系统下的局部广义力根据局部坐标系统和全局坐标系统间的矢量变换关系平移到全局坐标系统原点并求和，得到多维力传感器的多维力。
上述多维力传感器结构通过以下步骤获取多维力的具体过程如下：
建立附着于支撑平台上的全局坐标系统oxyz；
外力作用下负载平台在全局坐标系统oxyz下产生位移
其中，
为局部坐标系o
ix
iy
iz
i下的直线位移；
为局部坐标系o
ix
iy
iz
i下的转角位移；
分别建立附着于应变梁上的局部坐标系统o
ix
iy
iz
i；i表示应变梁的序号；
以应变梁与支撑平台接触面中心为局部坐标系原点
分别建立支撑平台局部坐标系统
局部坐标系统中应变梁在力作用下产生变形位移，
其中
为局部坐标系o
ix
iy
iz
i下的直线位移；
为局部坐标系o
ix
iy
iz
i下的转角位移；
根据应变梁上粘贴的应变片，或/和压电晶体作为应变梁，或/和负载平台和支撑平台之间设置的位移传感器，得到负载平台与相应局部坐标系原点重合点在局部坐标系下沿测量轴线的局部变形位移，称为可观测量；根据空间矢量变换可以利用所述的部分局部坐标系下的局部位移，即可观测量，计算出负载平台在全局坐标系统oxyz下产生位移
进而计算出所有应变梁局部坐标系下的局部位移
根据所述的得到的所有应变梁的
可以得到所有应变梁的局部广义力
其中
为局部坐标系o
ix
iy
iz
i下的力，
为局部坐标系o
ix
iy
iz
i下的力矩；
定义应变梁在局部坐标原点o
i的柔度矩阵为
采用有限元分析的方法或者试验方法获得应变梁的在局部坐标原点o
i的柔度矩阵
或者，针对等截面直杆应变梁，采用 Euler、Timoshenko或高阶现代梁理论，根据该应变梁的受力变形关系确定柔度矩阵
对于负载平台和支撑平台，将负载平台和支撑平台看做半弹性空间；定义负载平台在局部坐标原点o
i的柔度矩阵为
定义支撑平台在支撑平台局部坐标原点
的柔度矩阵为
采用有限元分析的方法或试验方法获得柔度矩阵均
和
或者，采用Boussinesq、Mindlin或现代高阶半弹性空间理论推导柔性矩阵
和
的近似值；
将支撑平台对应的柔度矩阵
移动到点o
i，在局部坐标o
i处负载平台、支撑平台的弹性变形部分与应变梁的柔度矩阵之和为：
表示从局部坐标系
到局部坐标系o
ix
iy
iz
i的空间矢量变换矩阵；进而获得柔度和矩阵的逆矩阵，即其刚度矩阵
将局部坐标系转换到全局坐标下得到全局坐标下刚度矩阵
表示从坐标系o
i到坐标系o的空间矢量变换矩阵；
则在全局坐标系下的原点处的所有应变梁、负载平台、支撑平台的刚度矩阵和为
全局坐标系下负载平台承受的外部广义力为
全局坐标系下负载平台在承受外部力时的广义位移为
全局坐标系统下广义力和广义位移、刚度的关系为：
全局坐标系统下的广义力和应变梁局部坐标系统下的局部广义力的关系为：
其中
表示从坐标系o
i到坐标系o的空间矢量变换矩阵；
可以根据上述获得的
和
采用公式
计算六维力
也可以根据上述获得的
采用公式
计算六维力
本发明的有益效果：
可以极大地提高多维力传感器负载平台微位移的测量精度，可以极大地扩展测量负载平台微位移的测量敏感元件安装方法与手段，最终提高多维力传感器的测量精度，同时可 以通过并联杆系方式有效地提高多维力传感器的结构刚度。
图1为多维力(六维力)传感器结构示意图；
图2为局部坐标系统示意图；
图3为每个局部坐标系统与全局坐标系统的关系确定过程示意图；
图4为局部坐标系统中应变梁在力作用下的变形示意图；
图5为应变梁可以为任意形状应变梁示意图；
图6为弹性半空间刚性平面受力示意图；
图7为螺栓连接受力过程中接触表面部分脱离示意图；
图8为平面对称8应变梁多维力传感器；
图9为典型应变片处理电路；
图10为一些经典的平面三维力传感器结构示意图；
图11为一个典型空间六维力传感器结构示意图；
图12为一些典型的整体式空间六维力传感器结构及加工顺序示意图；
图13为一些典型的整体式空间六维力传感器结构示意图；
图14为一些典型的焊接及机械连接式六维力传感器结构示意图；
图15为一些典型的平面嵌入式连接方法示意图；
图16为一些典型的嵌入式空间六维力传感器结构示意图；
图17为压装式结构压装方法及传感器的安放位置示例；
图18为整体外壳情况下压块应变梁嵌入压装结构方式；
图19为分体外壳情况下压块应变梁嵌入压装结构方式；
图20为采用拉式应变梁与压装结构结合的方法；
图21为压装式结构中采用电容传感器测量负载平台和支撑平台相对位移方法；
图22为一个典型的压装式空间六维力传感器结构示意图；
图23为压装式结构上下两个支撑平台连接示意图；
图24分别为8梁和12梁压装式结构负载平台示意图；
[根据细则91更正 12.08.2020]
图25为三种悬线式结构多维力传感器。
图25为三种悬线式结构多维力传感器。
[根据细则91更正 12.08.2020]
所有附图中的英文对应的中文含义如下：
Loading platform：负载平台，Supporting platform：支撑平台，Strain gauge：应变片，Fixed on supporting platform：固定于支撑平台，Initial state：初始状态，Rotation about x/y/z：绕 x/y/z轴旋转，Transformation along x/y/z：沿x/y/z轴移动，Connection with loading platform：与负载平台连接，Displacement of loading platform：负载平台位移，Displacement of o in global coordinate system：o点在全局坐标系统中位移，Displacement of oi in global coordinate system：o
i点在全局坐标系统中位移，Displacement of oi in local coordinate system：o
i点在局部坐标系统中位移，Bending deformation by F：由F引起的弯曲变形，Shear deformation by F：由F引起的剪切变形，View A：视图A，Elastic half-space：弹性半空间，Rigid plane：刚性平面，Capacitive sensor：电容传感器，Piezoelectric crystal：压电晶体，Sufficient gap for deformation of the beam:应变梁变形的足够间隙，Head of the beam:应变梁头部，Squeeze the head into the hole:将头部挤压入孔洞，Maintenance hole:维修孔，Suspending wire:悬线；
具体实施方式一：
本实施方式为并联杆系多维力传感器结构，包括支撑平台、负载平台，负载平台和支撑平台通过并联杆系连接，并联杆系的每一根杆都作为一根独立应变梁设置于负载平台和支撑平台之间，负载平台所受外力完全由并联杆系传递至支撑平台上；所述的并联杆系可以从一根到任意多根应变梁组成；
在支撑平台和负载平台之间布置有测量两者之间微位移的微位移传感器，和/或，在并联杆系的应变梁上设置有应变片，和/或，采用压电晶体作为应变梁。
可以通过应变梁变形，或负载平台和支撑平台之间的微位移计算出负载平台所受的多维力；
通过应变梁变形的方式：应变梁上粘贴应变片或采用压电晶体做为应变梁，通过应变片测量的应变或压顶晶体测量的电荷变化计算得到应变梁在局部坐标系统中的应变梁变形，该变形可以进一步用来计算负载平台变形位移，进而得到多维力。
通过负载平台和支撑平台之间的微位移的方式：在负载平台和支撑平台之间布置测量两者之间位移的微位移传感器，通过微位移传感器在其自身局部坐标系统中的测量量计算负载平台变形位移，进而得到多维力。
采用的多维力计算方法为通过微位移传感器、应变片、压电晶体获得相应微位移传感器及应变梁在其局部坐标系统下相应测量敏感轴线的微位移，该微位移称为可观测量，并通过空间矢量变换方式获得负载平台的微位移与局部坐标系统微位移的协调关系方程组，并通过抽取协调关系方程组中特定方程的方式建立负载平台微位移求解方程组，利用上述获得的可观测量求解该负载平台微位移求解方程组，最终获得负载平台在全局坐标系统中 的微位移；利用负载平台微位移进一步求解每一根应变梁的所有局部微位移，更进一步求解每一根应变梁的局部力，并最终可以通过力变换后求和的方式得到多维力传感器所受的多维力。
多维力传感器结构包括整体式，焊接及机械连接式，嵌入式，压装式和悬线式等类型；
(1)所述整体式为：负载平台、支撑平台和应变梁一体式结构，即通过一块整体材料采用机械加工方式(如镂铣等)制造完成，负载平台和支撑平台之间的力在一块整体材料中完成传递；其目的在于当支撑平台受力，应变梁变形时，在力传递路径上所有部位的刚度都保持不变，避免出现部分部位刚度的突变。
(2)所述焊接及机械连接式为：应变梁采用焊接或机械连接结构分别与负载平台和支撑平台连接，负载平台和支撑平台之间的力传递要通过焊接或其它机械连接结构进行传递，焊接部位及其它接触部位在受力过程中均应基本保持接触；其目的在于当支撑平台受力，应变梁变形时，应变梁与负载平台及支撑平台之间的接触面的接触刚度基本保持不变。
(3)所述嵌入式为：应变梁采用嵌入式结构分别与负载平台和支撑平台连接，负载平台和支撑平台之间的力传递要通过嵌入式结构进行传递，在连接时采用压力装配方法将嵌入端压入相应的嵌入孔，或者嵌入端与嵌入孔通过其他介质连接，使所有的接触面之间均产生预应力，且在受力过程中所有的接触面仍保持一定的预应力，进而保证所有接触面不会脱离，即：采用嵌入式预紧结构避免传感器受力过程中应变梁与平台接触面的脱离；其目的在于当负载平台受力，应变梁变形时，应变梁与负载平台及支撑平台之间的接触面的接触刚度保持不变。
(4)所述压装式为：应变梁采用压装式结构与负载平台和支撑平台分别连接，负载平台和支撑平台之间的力传递要通过压装式结构进行传递；所述的压装式结构指通过压力装配方式使应变梁两端与负载平台和支撑平台接触面均保持一定的预压应力，且在受力过程中所有的接触面仍保持一定的预压应力，进而保证接触面在受力过程中不会脱离，即：采用压装式结构避免传感器受力过程中应变梁与平台接触面的脱离；；其目的在于当支撑平台受力，应变梁变形时，应变梁与负载平台及支撑平台之间的接触面的接触刚度保持不变。
(5)所述悬线式为：每根应变梁均为一根细的悬线，分别与负载平台和支撑平台连接，所有的悬线应变梁均施加一定的预拉应力，且在受力过程中一直保持拉应力；其目的在于当负载平台受力，悬线应变梁变形时，各部位包括悬线应变梁部位的刚度保持不变。
本发明多维力传感器的解算方式如下：
首先对空间矢量符号的表示形式进行说明，例如
每个参数的整体作为一个形式进行说明：
符号的主体表示空间矢量，Q表示包括力和力矩的广义力，F表示力，M表示力矩；Δ表示包括直线位移和转角位移的广义变形位移，ΔD表示直线变形位移，Δθ表示转角变形位移；r表示局部坐标系原点在全局坐标系下的与全局坐标系原点的距离，β表示局部坐标系绕全局坐标系三个轴的转角；
左上角的上角标代表坐标系统，左上角的上角标为g表示对应的参数为全局坐标系oxyz下的参数；左上角的上角标为i表示对应的参数为应变梁局部坐标系o
ix
iy
iz
i下的参数；左上角的上角标为j表示对应的参数为位移传感器局部坐标系o
jx
jy
jz
j下的参数；
左下角的下角标代表矢量作用的点，左下角的下角标为o表示对应的矢量作用在全局坐标系oxyz的原点o；左下角的下角标为o
i/o
j分别表示对应的矢量作用在应变梁/位移传感器局部坐标系o
ix
iy
iz
i/o
jx
jy
jz
j的原点o
i/o
j；
右上角的上角标为i/j分别表示施加者为第i根应变梁或第j个传感器；g或者空白，表示为全局量，即施加者为负载平台上的外力；
右下角的下角标代表矢量的方向，右下角的下角标为x表示沿着x轴，右下角的下角标为y表示沿着y轴，右下角的下角标为z表示沿着z轴，右下角标带有F和M是指变量由力或力矩引起，不带指由力和力矩共同作用引起，右下角的下角标空白表示xyz轴共同构成的矢量。
例如，
表示第i根梁，在全局坐标系统oxyz(即g)下，作用于o
i点，沿全局坐标系统x方向的力F；
表示第i根梁，在局部坐标系统i(即o
ix
iy
iz
i)下，作用于o
i点，在转矩M的作用下导致的沿该局部坐标系统z
i方向的直线位移ΔD。
由于多维力传感器的负载平台微位移测量方法是多维力获取方法的基础，所以先说明一下采用并联杆系的多维力传感器的多维力获取方法；
将负载平台及支撑平台视为伪刚体，在负载平台上可以将所有受外力变形部分及每一根连接应变梁变形部分进行隔离，在支撑平台上可以将所有支撑力变形部分及每一根连接应变梁变形部分进行隔离；通过弹性力学的梁理论与理论力学的力空间变换理论将每根应变梁的变形位移与受力与作为伪刚体的负载平台位移与受力联系起来，通过应变梁的应变或压电变化或负载平台与支撑平台之间的微位移变化得到负载平台所受外力，其计算方法为：
首先建立各坐标系：
建立附着于支撑平台上的全局坐标系统，即该坐标系统固联于支撑平台不运动，但为 了显示方便，一般将坐标系原点放置于负载平台受力部分中心o。如图1所示，图中全局坐标系为oxyz，简记为xyz；y轴与x轴垂直，z轴与平面y-x垂直；
建立表达应变梁局部変形的的局部坐标系统，图中局部坐标系为o
ix
iy
iz
i，简记为x
iy
iz
i，其中i表示第i根梁；以应变梁与负载平台接触面中心为局部坐标系原点o
i；如图2所示，以应变梁中心线为局部坐标系x
i轴，y
i轴与x
i轴垂直，且y
i轴处于应变梁端面内，z
i轴与平面y
i-x
i垂直，该局部坐标系统建立后即视为在全局坐标系统中固定，并不随应变梁变形而改变，其具体建立方式如下所述：
每个局部坐标系统与全局坐标系统的关系都可以用三个旋转角度和三个平移距离来表示，记为
和
如图3所示，图3表示每个局部坐标系统与全局坐标系统的关系确定的过程，即梁局部坐标系统的的建立方式；即：初始状态为局部坐标系与全局坐标系重合，先将应变梁相对初始位置沿着x旋转
再沿着y旋转
再沿着z旋转
然后沿着xyz坐标轴分别平移
再将应变梁两端分别连接到负载平台和支撑平台上；当负载平台受力产生位移后，负载平台上与全局坐标系原点的重合点从o移动到o′；应变梁上与局部坐标系原点o
i的重合点移动到o
i′，我们将这种局部坐标系统的建立方式称为Coordinate Ma；
局部坐标系统中应变梁在力作用下的变形示意图如图4所示；采用Euler梁时(也可采用Timoshenko梁或其它高阶梁)，根据应变梁的受力关系可知：
E为弹性模量，G为剪切模量；l
i是应变梁长度；A
i为应变梁横截面面积；
为绕y
i轴的惯性矩；
为绕z
i轴的惯性矩；
(实际上就是
一般写为
)为绕x
i轴的惯性矩，也称极惯性矩；
与上述空间矢量符号的表示形式是相同的，右下角的下角标代表矢量的方向，仍然是右下角的下角标为x表示沿着x轴，右下角的下角标为y表示沿着y轴，右下角的下角标为z表示沿着z轴；右下角的下角标中还出现其它参数就表示对应参数在相应轴上的量，例如右下角的下角标为Mz就表示由于M导致在z上的量。
应变梁在局部坐标原点o
i的柔度矩阵定义为：
应变梁可以为任意形状应变梁，如图5所示。对于任意形状的应变梁，可以采用有限元或试验方法获得应变梁的在局部坐标原点o
i的柔度矩阵；对于等截面直杆应变梁，还可以根据前述的该应变梁受力变形关系，进一步根据Euler-Bernoulli梁理论将柔度矩阵(该矩阵也可以根据Timoshenko梁及其它现代梁理论获得)写为：
弹性半空间刚性平面受力示意图如图6所示，对于负载平台和支撑平台，可以将负载平台和支撑平台看做弹性半空间，其与应变梁连接处的柔度矩阵可以通过弹性半空间上的 刚性平面受力位移变形关系得到；
负载平台在局部坐标原点o
i的柔度矩阵定义为：
以应变梁与支撑平台接触面中心为局部坐标系原点
建立支撑平台局部坐标系统(与建立在应变梁与负载平台接触面中心的局部坐标系统相似)；支撑平台在支撑平台局部坐标原点
的柔度矩阵定义为：
可以采用有限元或试验方法获得柔度矩阵均
和
也可以采用Boussinesq和Mindlin等的半弹性空间理论推导该柔性矩阵近似值：
式中：E-弹性模量；μ-泊松比；A-刚性平面面积；I
p-刚性平面绕x轴极惯性矩；r
p-刚性平面绕x轴极惯性半径；s-刚性平面沿z轴边长；w-刚性平面沿y轴边长；
应变梁对应的柔度矩阵
负载平台对应的柔度矩阵
支撑平台对应的柔度矩阵
均需要在点o
i上进行处理，并对其求和；所以将支撑平台对应的柔度矩阵
移动到点o
i；
为了后续说明方便，定义一种通用变换矩阵为：
为坐标系p到坐标系q的空间变换矩阵，其中o
p,x
p,y
p,z
p分别表示坐标系p的坐标原点，x轴，y轴和z轴，o
q,x
q,y
q,z
q分别表示坐标系q的坐标原点，x轴，y轴和z轴，γ＝[γ
x,γ
y,γ
z]
T为坐标系p和坐标系q在坐标系q内绕x，y，z的空间夹角，d＝[d
x,d
y,d
z]
T为坐标系p和坐标系q坐标原点在坐标系q内沿x，y，z的距离，其具体含义如下：
Rot(γ)＝Rot(z,γ
z)Rot(y,γ
y)Rot(x,γ
x) (13)
Rot()指空间旋转变换；其逆变换为：
Rot
T(γ)＝Rot
T(x,γ)Rot
T(y,γ)Rot
T(z,γ) (14)
代表矢量d＝[d
x，d
y，d
z]
T对应的反对称算子；该算子也可以看做叉乘算子，即力与力臂叉乘转换为力矩，及转速(微转角或转角差分)与转动半径叉乘转换为直线速度(微位移或位移差分)；
在具体应用
时，将p和q替换为具体的坐标系统，将γ替换为具体的两个坐标系统的夹角，将d替换为具体的两个坐标系统的原点距离即可，例如后面所述的
即为从梁与支撑平台相交处的坐标系
到梁与负载平台相交处的坐标系i的空间变换，
即为从梁与负载平台相交处的坐标系i到全局坐标系统g的空间变换。
在局部坐标o
i处的柔度和矩阵
当应变梁为直梁时，
其中l＝[l
x，l
y，l
z]
T代表两个局部坐标系o
ix
iy
iz
i和
原点在局部坐标系o
ix
iy
iz
i中的距离；
对于每一根应变梁i，在其局部坐标系原点的柔度矩阵都可以采用上述方法获得；
单根应变梁以及分别与负载平台、支撑平台连接处的柔度和矩阵的逆矩阵，即其刚度矩阵
局部坐标系转换到全局坐标下刚度矩阵的转换公式为：
T
i
g表示从坐标系o
ix
iy
iz
i(i)到坐标系oxyz(g)的空间变换矩阵，坐标系i与坐标系g之间的夹角为β
i，原点间距离为r
i；
以图1所示的六维力传感器为例，在全局坐标系下的原点处的所有应变梁、负载平台、支撑平台的刚度矩阵和为
图1所示的空间六维力传感器与其完全一致；
全局坐标系下负载平台承受的外部合力为
全局坐标系下负载平台在承受外部力时的位移为
力和位移、刚度的关系可以写为：
在多维力传感器实际测量时，由于刚度矩阵只与实际结构相关，所有结构参数事先已经得到，只要测量出负载平台在外力作用下的六个方向的微位移，即可以得到外部负载力六个分量的大小，即：只要通过支撑平台和负载平台之间布置的微位移测量传感器，和/或，应变梁上粘贴有的应变片，和/或，采用压电晶体作为应变梁，测量得到负载平台在外力作 用下的六个方向的微位移，即可以得到多维力传感器获得多维力，包括三维力，六维力及其它维度力。
本发明中将该计算方法称为Principle Ma。
目前本领域中还没有本发明所述结构的多维力传感器，是现有的多维力传感器的解算方式决定的，目前的多维力传感器的解算方法都是认为六维力一定与结构体某些薄弱部位的应变直接呈现线性关系，忽略掉了所有里传递过程中的交叉耦合，或是认为结构体均为纯刚体，通过无摩擦铰链连接，忽略掉所有的结构体变形和摩擦力，因而导致结构体或者过于复杂，具有大量的并串联结构体，或者过于简单，采用铰链结构解耦所有力。本发明中的多维力传感器结构对于传统的解算方法而言都无法求解。
也正是基于上述原因，本发明结构有一些在其它领域虽然也有所体现，但现有的多维力传感器并不会采用本发明的结构，也不会想到使用本发明的结构，因为现有技术并没有一种本发明结构对应的解算方式，自然现有技术中也就不会想到本发明对应的结构。
实施例
该类传感器要得到高的测量精度，就必须要保证在测量过程中，多维力从负载平台经过应变梁传递到支撑平台，整个力的传递路径上，所有部位的结构刚度需要保持基本不变，而通常的焊接及螺栓连接等结构中两个零件的接触面在整个受力过程中很容易发生局部接触面脱离接触现象，进而导致接触面的接触刚度发生突变，令多维力测量结果精度降低，本发明通过多种结构设计方案保证力传递路径上结构刚度的不变性。
多维力学传感器可以分为2维力(平面2维力或1维力加一维力矩)3维力(平面2维力加平面内转矩，或立体沿3个坐标轴力，或绕3个坐标轴转矩)，4维力，5维力及6维力传感器。其中平面3维力(平面2维力加平面内转矩)和立体6维力传感器为最通用的传感器，其它传感器均可以在此基础上通过忽略某一些维度力(力矩)得到。
本发明的多维力传感器均有多根并联结构的应变梁构成，可分为整体式结构、焊接机及机械连接结构、嵌入式结构和压装式结构。
结合附图说明本发明多维力学传感器结构，每一种结构均有平面三维力和立体六维力两种形式。
如图7(a)和图7(b)所示，应变梁和基础平台(负载平台和支撑平台)通过螺栓连接在一起，在应变梁受到力的作用情况下，应变梁与基础平台的接触面会发生变形，在变形比较大时原来的接触面会部分脱离接触，进而导致接触刚度发生突变，接触面附近应变的位移传递也会发生突变，最终导致计算得到的多维力结果不准确；这种结果是多维力传感器结构设计中应尽量避免的；不只是这种螺栓连接结构会发生受力过程中局部刚度的变 化，其它种类的结构中也会发生类似的问题，因此下述所有结构都着重于解决此类问题。
这种限定的有益结果就是避免力传递路径上某些部位刚度突变现象的发生，进而有效地保证负载平台微位移计算精度，最终保证多维力传感器精度。
一、整体式结构
整体式结构指除了辅助零件(外壳、外部转接件等)整个传感器(主要包括应变梁、负载平台和支撑平台)由一整块工件加工而成。该种结构的好处是应变梁在与支撑平台和负载平台的连接处为一个均匀连续的整体，不会产生刚度的突变，测量精度较高。该结构尤其适合几百公斤负载以下的中小型、微型及MEMS结构多维力传感器，应用于力控机器人、协作机器人、腔镜微创手术机器人、仿生机械臂、以及其他中小型多维测力装置。
1、平面三维力传感器结构
平面结构三维力传感器指负载平台、支撑平台和梁结构均布置在一个平面或相互平行的多个平面内，可以将其结构关系投影在一个平面内，可以表征的力包括投影平面内的两个力和一个力矩，如图8所示。
以应变片粘贴于应变梁四个面的中心位置为例，，可以用于测量应变梁沿应变梁轴向x
i的平均拉/压应变(应力)。
图9(a)和图9(b)中E为外加基准电压，e为测量电压。也可以采用频率法等方法测量应变片应变。应变片可以采用通用的差动电桥测量，也可以直接测量每一路应变片应变量，再通过数字电路进行处理，进而测量出应变片1和应变片3的应变和或者应变片2和应变片4的和，或者全部4个应变片1、2、3、4的和。这样可以将弯曲应力忽略，只得到应变梁拉/压应力，进而得到应变梁沿轴线方向x
i的拉/压力。
图10(a)至图10(f)分别为典型的整体式平面三维力传感器，应变梁包括等截面应变梁和变截面应变梁。
2、立体六维力传感器结构
立体六维力传感器指负载平台、支撑平台和梁结构布置空间立体结构内，可以表征的力包括三个力和三个力矩；如图11(a)和图11(b)所示；
图12(a)和图12(b)分别表示一体式立体六维力传感器结构的加工过程。
一体式结构包括但不限于图11(a)和图11(b)所示的结构，也可以是图13(a)至图13(f)所示的其他形式等结构。
二、焊接及机械连接结构
如图14(a)至图14(b)所示，焊接及机械连接结构采用分别独立加工支撑平台、负载平台和应变梁之后再将三者组装在一起的方式完成整个传感器主体结构。焊接及机械连 接结构包括但不限于图14(a)和图14(b)所示的结构，也可以是图14(c)至图13(d)所示的其他形式等结构。
其特点是加工制造比较方便，尤其是便于大型重载传感器的制造。需要注意的是焊接或者螺栓连接部位的结构尺寸要大于应变梁的截面尺寸，以保证焊接部位或者螺栓连接部位的结构刚度要大于应变梁部位的结构刚度。螺栓连接的预紧力要足够大，以保证受力过程中接触面不会发生局部脱离现象。
三、嵌入式结构
嵌入式结构的特点是可以采用刚度较低的应变梁材料和刚度较大的支撑平台和负载平台结构，例如支撑平台和负载平台采用钢材、钛合金等材料，而应变梁采用橡胶、电木、塑料等材料，进而可以保证在较小受力情况下可以产生较大应变梁变形，比较适合微小力测量。
1、平面三维力传感器结构
平面三维力传感器结构包括但不限于如图15(a)所示的结构。
在本实施例中，嵌入式采用挤压式预紧的方式，如图15(b)所示，应变梁两端做出比较大的头部，在负载平台和支撑平台上做出与之对应的嵌入孔，孔的尺寸比应变梁头部稍小，采用机械挤压方式将应变梁头部分别挤压入负载平台和支撑平台上的嵌入孔。其目的是在头部和平台之间的接触面上产生预应力，令测量过程中接触面不会部分脱离接触，从而接触刚度不会变化。
嵌入式也可以采用其他形式，如图15(c)所示的楔块预紧方式。
楔块预紧方式的顶部可以采用压板预紧，如图15(d)所示，当让也可以不采用这种形式。该种压板预紧不只适用于楔块预紧式，同样适用于其它挤压式等预紧方式；
嵌入式也可以采用其他形式，如图15(e)所示的注入式连接方式，即采用注入可凝固液体方式进行连接，如注入液态金属、树脂等。
当然，也可采用先用挤压式连接，再焊接方式，如图15(f)所示。
或者也可以采用嵌入端螺栓连接方式，即采用螺栓进行挤压或拉紧嵌入端的方式进行连接，如图15(g)和图15(h)所示。该种连接方式经纪方便，但容易出现接触刚度小，接触面部分脱离问题，需要仔细考虑负载力大小，适当增大螺栓直径。
所有的嵌入式结构接触面最好也要保证受力过程中不应出现局部脱离现象。
2、立体六维力传感器结构
立体六维力传感器结构的嵌入方式相同，只是其结构为立体结构，如图16(a)至图16(c)所示。当然本发明包括但不限于这几种形式。
四、压装式结构
压装式结构特点是将薄型弹性梁通过预紧力压装与负载平台和支撑平台之间，所有的弹性梁不同时在一个平面，装配时施加预紧力，令弹性梁产生受压预紧力，并在测量过程中式中保持受压状态，避免弹性梁与负载平台及支撑平台脱离。应变梁可以采用压电晶体，通过压电效应测量，也可以采用其它材料通过在应变梁上粘贴应变片或在应变梁上安装微位移传感器，或在负载平台和支撑平台之间安装微位移传感器进行测量。
可以采用如图17(a)至图17(c)所示，其中图17(a)为在负载平台和支撑平台之间直接设置应变梁，图17(b)为在负载平台和支撑平台之间的部件内部设置应变梁，图17(c)在应变梁的上下端设有电容式传感器。
1、平面三维力传感器结构
整体预紧式：
如图18所示的整体预紧式平面三维力传感器，整体预紧式是指支撑平台和负载平台都分别是一个整体式结构，安装应变梁时需要通过压力机等施加外力将平台撑开，然后放入应变梁(图18中位于四个角处)，撤掉外力后则平台回弹，进而实现对应变梁的预紧。本发明包括但不限于图18所示的整体预紧式平面三维力传感器。
立体六维力传感器也可以采用同样的方式进行预紧。
支撑平台预紧式：
如图19所示的支撑平台预紧式平面三维力传感器，支撑平台预紧式指将支撑平台分为分体结构，在装配过程中令支撑平台的不同部分采用螺栓或焊接及其他连接方式连接为一体时对弹性梁产生受压预紧力。
梁预紧式：
如图20(a)和图20(b)所示的梁预紧式平面三维力传感器，梁预紧式指采用可以受拉的预紧梁(一般采用金属梁)对薄壁弹性梁(一般采用非金属梁)进行预紧，预紧梁可以放置于薄壁弹性梁外(图20(a))，也可放置于薄壁弹性梁中间(图20(b))。该种结构的特点是在传感器测量过程中，预紧梁的受力也要在计算中考虑。
多维力传感器受力计算可以采用测量弹性梁的受力方式计算，也可以采用测量负载平台和支撑平台间的微位移方式计算。
负载平台和支撑平台间的微位移可以采用多个微位移传感器(电容、电感、电涡流、三角光、共焦光、像散光等)测量得到，以图中的电容传感器为例，可以布置于弹性梁外部，也可布置与弹性梁上，如图21(a)和图21(b)所示。
当应变梁为压电晶体时，可以直接利用压电晶体受力产生的电荷量变化进行计算。
薄壁应变梁以及预紧梁上也可布置应变片(电学、光学)，通过测量应变进行计算。
1.立体六维力传感器结构
立体六维力的布置方式与平面式基本类似，所有的弹性梁不同时布置于同一平面内，也可以采用平台预紧和预紧梁预紧两种方式，测量方法可以采用采用测量负载平台和支撑平台间的微位移、压电晶体测量和布置应变片三种方式。
图22为压电晶体布置与预紧示意图，图中的压电晶体即可以视为应变梁，采用压电晶体时可以直接根据压电晶体的电荷变化量计算六维力；图中的压电晶体也可以替换为其它材料，此时需要在负载平台和支撑平台间布置微位移传感器，通过微位移传感器的变化量计算六维力；本图中的支撑平台分为上下两部分，具体结构中需要连接为一体；
图23为支撑平台分体结构及连接方式的示意图。对于图22中的上下两个支撑平台，可以用本图中的结构连接于一体，同时对应变梁施加预紧力。
图24(a)和图24(b)为分别为8块压装式应变梁和12块压装式应变梁负载平台结构的示意图，本图中只给出了负载平台及应变梁结构，相应的支撑平台结构可以参考上面图22。
五、悬线式结构
图25为三种悬线式结构多维力传感器，图25(a)为一种平面结构，采用夹持和预紧结构将所有悬线拉紧，图25(b)为一种嵌入是平面结构，悬线与两端的嵌入块为一体化结构，采用嵌入式将悬线固定并预紧，图25(c)为一种立体结构，支撑平台分为上装支撑平台和下装支撑平台，两个支撑平台之间需要采用固定结构进行连接并对悬线施加预紧力。该种结构的好处是悬线式应变梁可以非常细，进而可以将支撑平台和负载平台看做极为接近理想刚体的伪刚体，其结构承载力较小，但多维力测量精度极高。
本发明包括但不限于图8至图25所示的多维力传感器结构，可以是本发明实施例中所有结构相互组合的形式或者其他形式。
Claims (6)
- 并联杆系多维力传感器结构，其特征在于，包括支撑平台、负载平台，负载平台和支撑平台通过并联杆系连接，负载平台所受的外力完全通过并联杆系传递到支撑平台上；在支撑平台和负载平台之间布置有测量两者之间微位移的微位移传感器，和/或，在并联杆系的应变梁上设置有应变片，和/或，采用压电晶体作为应变梁。
- 根据权利要求1所述的并联杆系多维力传感器结构，其特征在于，所述多维力传感器结构包括整体式，焊接及机械连接式，嵌入式，压装式和悬线式类型；所述整体式为：负载平台、支撑平台和应变梁为一体式结构，即采用一整块连续材料加工而成；所述焊接及机械连接式为：应变梁采用焊接或机械连接结构分别与负载平台和支撑平台连接；所述嵌入式为：应变梁采用嵌入式结构分别与负载平台和支撑平台连接；所述压装式为：应变梁采用压装式结构分别与负载平台和支撑平台连接；所述悬线式为：每根应变梁均为一根悬线，分别与负载平台和支撑平台连接，所有的悬线应变梁均施加一定的预拉应力，且在受力过程中一直保持拉应力。
- 根据权利要求2所述的并联杆系多维力传感器结构，其特征在于，所述嵌入式的形式包括挤压式预紧方式、楔块预紧方式、注入式连接方式、先挤压后焊接方式、嵌入端螺栓连接方式。
- 根据权利要求2所述的并联杆系多维力传感器结构，其特征在于，所述压装式的形式包括整体预紧方式、支撑平台预紧方式、梁预紧方式。
- 根据权利要求1所述的并联杆系多维力传感器结构，其特征在于，所述多维力传感器受到力的作用时，应变梁与负载平台和支撑平台的接触面始终保持接触。
- 根据权利要求1至5之一所述的并联杆系多维力传感器结构，其特征在于，所述多维力传感器结构通过以下步骤获取多维力：全局坐标系统为附着于支撑平台上的坐标系统；应变梁局部坐标系统为附着于应变梁上的坐标系统；微位移传感器局部坐标系统为附着于微位移传感器上的坐标系统；根据空间矢量变换法则建立局部坐标系统和全局坐标系统间的矢量变换关系矩阵，包括广义力变换关系、广义变形位移变换关系和位移传感器变换关系；所述的广义力包括力和力矩，所述广义变形位移包括直线位移和转角位移；根据理论力学、材料力学和弹性力学建立局部坐标系统下的应变梁、支撑平台及负载 平台的变形和受力的关系矩阵，即局部刚度矩阵和局部柔度矩阵；根据应变梁上粘贴的应变片，或/和压电晶体作为应变梁，或/和负载平台和支撑平台之间设置的位移传感器，得到负载平台与相应局部坐标系原点重合点在局部坐标系下沿/绕测量轴线的局部变形位移，称为可观测量；根据所述负载平台与相应局部坐标系原点重合点在局部坐标系沿/绕测量轴线的局部变形位移计算负载平台在全局坐标系统下的变形位移；根据负载平台在全局坐标系统下的变形位移计算每个应变梁相应局部坐标原点在局部坐标系统下的所有局部变形位移；根据每个应变梁在局部坐标系统下的局部变形位移计算每个应变梁在局部坐标系统下的局部广义力；将所有应变梁在局部坐标系统下的局部广义力根据局部坐标系统和全局坐标系统间的矢量变换关系平移到全局坐标系统原点并求和，得到多维力传感器的多维力。
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