Surface contact force solving method of robot dexterous hand and tactile fingertip

Abstract

The application provides a surface contact force solving method of a robot dexterous hand and a tactile fingertip, and comprises the following steps: calculating the node load of each sensor according to the reading of the sensor array in the tactile fingertip; summing up the node load of each sensing unit to obtain the total load; calculating the two-dimensional pressure center on the sensing base surface according to the position of each sensing unit and the corresponding node load; mapping the two-dimensional pressure center to the three-dimensional curved surface based on the geometric equation of the three-dimensional curved surface of the tactile fingertip to determine the position of the three-dimensional contact point and calculate the normal vector at the three-dimensional contact point; compensating and calculating the total load based on the physical model of the force transmission medium to obtain the total normal contact force acting on the position of the three-dimensional contact point; and determining the three-dimensional normal contact force vector according to the normal vector and the total normal contact force. The application can accurately solve the position of the three-dimensional contact point and the normal force vector, the solving algorithm is decoupled from the specific physical structure of the sensor, and has high universality.

Description

Technical Field

[0001] This invention relates to the field of robotics, specifically to a method for calculating surface contact force in a robot's dexterous hand and a tactile fingertip. Background Technology

[0002] When performing tasks such as grasping and manipulating, the tactile perception capabilities of a robot's fingertips are crucial. To achieve highly sensitive tactile perception, current technologies typically integrate sensor arrays, such as piezoresistive or capacitive sensor arrays, inside the robot's fingertips to detect external contact forces.

[0003] Patent document CN101576421A discloses a compliant tactile sensor for the dexterous fingertips of a humanoid robot. The compliant protective layer is bonded to the compliant piezoresistive sensitive layer. Multiple electrode pairs and multiple voltage output and input pins are etched on the upper and lower surfaces of the substrate. The E-type voltage output electrodes in each E-type voltage output electrode group are connected in parallel and then connected to the corresponding voltage output pin. The π-type voltage input electrodes in each π-type voltage input electrode group are connected in parallel and then connected to the corresponding voltage input pin. A pressure-sensitive conductive rubber body is disposed on the upper surface of the substrate. The side of the pressure-sensitive conductive rubber body is coated with adhesive and bonded to the compliant substrate layer.

[0004] However, the aforementioned existing technical solutions have the following shortcomings: First, because the robot's fingertips need to frequently interact with external objects, their outermost protective layer is prone to wear and even damage. In existing integrated designs, once a fingertip is damaged, the entire finger or even the dexterous hand usually needs to be sent back to the factory for repair. The replacement process is complex and time-consuming, resulting in long robot downtime and high maintenance costs. Second, for fingertips with three-dimensional curved surfaces, accurately retrieving the contact point, force magnitude, and force direction acting at any position on the three-dimensional curved surface based on the discrete readings of the underlying planar sensor array remains a technical challenge. Existing calculation methods are usually rather coarse and cannot meet the high-precision tactile feedback requirements of robots performing delicate operations. Summary of the Invention

[0005] In view of the shortcomings of the prior art, the purpose of this invention is to provide a method for calculating the surface contact force of a robot dexterous hand and a tactile fingertip, which aims to simplify hardware limitations, improve the accuracy of three-dimensional contact force perception and calculation, and enable rapid disassembly and maintenance of the fingertip.

[0006] This invention provides a method for calculating the surface contact force of a robot dexterous hand, applied to a tactile fingertip with a quick-change base. The method for calculating the surface contact force of the robot dexterous hand includes: The nodal load of each sensor is calculated based on the readings of the sensor array in the tactile fingertip. The total load is obtained by summing the nodal loads of each sensing unit. The two-dimensional pressure center on the sensing base surface is calculated based on the position of each sensing unit and the corresponding nodal load. Based on the geometric equation of the three-dimensional curved surface of the tactile fingertip, the two-dimensional pressure center is mapped onto the three-dimensional curved surface to determine the position of the three-dimensional contact point and calculate the normal vector at the three-dimensional contact point; Based on the physical model of the force transmission medium, the total load is compensated and calculated to obtain the total normal contact force acting on the three-dimensional contact point. The three-dimensional normal contact force vector is determined based on the normal vector and the total normal contact force.

[0007] Furthermore, through a pre-determined calibration function Calibrate each sensor, i=1, 2…N, where N is the number of sensors, and record the voltage value of each sensor. Convert to the corresponding pressure value , ,in Let be the calibration coefficient for the i-th sensor; Obtain the initial pressure reading under no-load conditions. The current pressure reading Subtract the initial pressure reading The net change in pressure caused by the external contact force is obtained. ; The pressure change of each sensor Multiplied by the effective pressure-bearing area on the circuit board The equivalent nodal load at the sensor location is obtained. , The total load for: .

[0008] Furthermore, the coordinates of the two-dimensional pressure center for:

[0009]

[0010] Will Mapping to a 3D surface The coordinates of the three-dimensional contact point on the z-axis are obtained from the above. 3D contact point The location is:

[0011] Indicates vector transpose; Calculate the three-dimensional contact point normal vector :

[0012] in, f x ( ), f y ( ) represents the partial derivative of the three-dimensional surface.

[0013] Furthermore, the medium force transmission term With protective layer elasticity Together they constitute the total normal contact force F N :

[0014] β This is the pressure transmission calibration coefficient. For the equivalent normal stiffness of the external protective layer, δ This represents the equivalent normal displacement of the external protective layer. Define normal vector n c Pointing outwards from the curved surface, the three-dimensional contact force acts on the fingertip. F 3D for:

[0015] The components of the three-dimensional contact force are:

[0016]

[0017]

[0018] in, , , Normal vector n c The amount.

[0019] Furthermore, the surface contact force calculation method also includes: performing elastic deformation compensation on the three-dimensional normal contact force vector based on the elastic model of the outer protective layer of the tactile fingertip.

[0020] A tactile fingertip for a robotic dexterous hand according to the present invention includes: Quick-change base, detachably connectable to the fingertips of a dexterous hand; A sensor array is mounted on the quick-change base; The controller is configured to perform the surface contact force calculation method of the robot dexterous hand.

[0021] Furthermore, the quick-change base includes a quick-change connector that is detachably connected to the fingertips of a dexterous hand, the quick-change connector comprising a mechanical quick-lock structure and signal conductive contacts.

[0022] Furthermore, the mechanical quick-lock structure includes a magnetic connection structure or a snap-fit ​​connection structure.

[0023] Furthermore, it also includes a pressure equalization sealing cavity located on the side where the sensor array is located. The pressure equalization sealing cavity contains a force transmission medium for transmitting the external contact force acting on the pressure equalization sealing cavity to the sensor array.

[0024] Furthermore, it also includes an external protective layer, which is connected to the quick-change base and located outside the pressure equalization and sealing cavity.

[0025] Compared with the prior art, the present invention has the following beneficial effects: This invention maps the two-dimensional pressure center of the sensing base surface to the three-dimensional curved surface of the fingertip, and compensates for this by combining a medium physical model and an elastic model of the external protective layer. This enables precise calculation of the three-dimensional contact point position and normal force vector. It breaks through the conventional approach that "contact position measurement must place the sensor on the contact surface." By leveraging the hydrostatic force transmission characteristics of the force-conducting medium, the three-dimensional coordinates of the curved surface contact point can be derived using a low-cost planar sensor array on the bottom surface. The contact position positioning accuracy is determined by the sensor resolution and the accuracy of the surface equation, resulting in high stability. Furthermore, it eliminates the need to place any sensing elements on the curved surface, significantly reducing the hardware cost and manufacturing complexity of curved surface tactile sensing, while also fundamentally avoiding the problems of wear and breakage of curved surface sensors.

[0026] This invention can simultaneously output three-dimensional contact position coordinates and complete three-dimensional contact force components through a single calculation, realizing full-dimensional tactile information perception of "position + force vector". It provides complete perceptual input for the force feedback control, grasping stability judgment and fine operation planning of robot dexterous hands, which can significantly improve the operation accuracy and task success rate of dexterous hands in unstructured environments.

[0027] Meanwhile, the solution algorithm of this invention is decoupled from the specific physical structure of the sensor, exhibiting extremely high versatility. Furthermore, the quick-change base, incorporating a mechanical quick-lock and conductive contacts, enables rapid assembly and disassembly of the tactile fingertip module and reliable signal transmission, significantly improving maintenance efficiency. Attached Figure Description

[0028] Other features, objects, and advantages of the present invention will become more apparent from the following detailed description of non-limiting embodiments with reference to the accompanying drawings: Figure 1 An exploded view of the quick-change tactile fingertip provided in an embodiment of this application; Figure 2 This is an exploded structural diagram of the quick-change tactile fingertip provided in an embodiment of this application from another perspective.

[0029] In the diagram: 1-Quick-change base; 2-Circuit board; 3-Sensor array; 4-Pressure equalization and sealing cavity; 5-Outer protective layer. Detailed Implementation

[0030] The present invention will now be described in detail with reference to specific embodiments. These embodiments will help those skilled in the art to further understand the present invention, but do not limit the invention in any way. It should be noted that those skilled in the art can make several changes and improvements without departing from the concept of the present invention. These all fall within the protection scope of the present invention.

[0031] Example 1 This application provides a basic implementation scheme for a robot's dexterous hand to quickly switch tactile fingertips, as well as a corresponding surface contact force calculation method, which aims to illustrate the core structure and working principle of this application.

[0032] Combination Figure 1 and Figure 2 As shown, the quick-change tactile fingertip of the robot dexterous hand in this embodiment can be specifically embodied as an integrated tactile fingertip module. It is understood that the tactile fingertip module can achieve a quick and detachable connection with the fingertips of the robot dexterous hand. Specifically, the tactile fingertip module includes: a quick-change base 1, a circuit board 2, a sensor array 3, a pressure-equalizing sealed cavity 4, and an external protective layer 5.

[0033] The quick-change base 1 serves as the structural foundation and connection interface for the entire tactile fingertip module. It can be made of lightweight, high-strength materials (such as aluminum alloy or high-strength engineering plastics) to ensure structural rigidity and lightweight design. It should be noted that at the end of the quick-change base 1 that connects to the fingertip of the dexterous hand, a quick-change connector is provided for rapid replacement. This quick-change connector integrates a mechanical quick-lock structure and signal conductive contacts.

[0034] As a preferred implementation, the mechanical quick-lock structure is specifically a magnetic connection structure. For example, one or more powerful permanent magnets (such as neodymium iron boron magnets) can be embedded in the tail of the quick-change base 1, while a corresponding ferromagnetic material or another set of magnets with opposite polarity is placed on the mating surface at the fingertip of the dexterous hand. In this way, when the tactile fingertip module approaches the fingertip, the magnetic force can automatically align it and firmly attach it, thereby completing the physical locking. Understandably, this design requires no tools and can be installed by an operator with one hand, offering extremely high convenience.

[0035] Accordingly, the signal conductive contact is used to establish a reliable electrical connection while physically locking, for transmitting sensor signals and power supply. As an optional implementation, the signal conductive contact can be designed as a combination of a ring electrode and a spring probe. Specifically, multiple concentric ring-shaped conductive electrodes can be arranged on the mating surface of the quick-change base 1, and multiple elastic spring probes can be arranged at corresponding positions on the fingertips. During mating, the spring probes abut against the ring electrodes with a preset pressure, thereby ensuring continuous and stable electrical signal transmission even with minor alignment errors or vibrations.

[0036] The circuit board 2 is fixed to the quick-change base 1, and is typically a printed circuit board on which the sensor array 3 is arranged. In one embodiment of this application, the pressure sensors in the sensor array 3 are preferably piezoresistive sensors, and are arranged in an array on the circuit board 2 (the plane of the circuit board is set to the z=0 plane). As a specific, but not limiting, layout, a 2x4 rectangular array can be used, that is, a total of 8 piezoresistive sensors are arranged. This array layout helps the subsequent algorithm to accurately calculate the position of the pressure center. It is understood that the signal output terminal of each piezoresistive sensor is connected to the aforementioned signal conductive contact through wiring on the circuit board 2. The planar coordinates of the sensors are .

[0037] The pressure-equalizing sealed cavity 4 is located on the side of the circuit substrate 2 where the sensor array is arranged, wherein the top outer surface of the pressure-equalizing sealed cavity 4 (the contact surface with the outside) is a three-dimensional curved surface, for example, a smooth three-dimensional arched curved surface that meets the requirements of ergonomics or gripping tasks, and this curved surface constitutes the main shape for interaction between the fingertip and the outside. The pressure-equalizing sealed cavity 4 contains a force-conducting medium inside. In this embodiment, the force-conducting medium is specifically a compressible fluid accommodated in a deformable airbag. The deformable airbag is made of soft, air-tight elastic material, and the compressible fluid is sealed and filled inside it, preferably dry inert gas, such as dry air or nitrogen. Therefore, when an external object contacts and presses the three-dimensional curved surface of the fingertip, the concentrated contact force first acts on the deformable airbag, the airbag deforms accordingly, the internal gas is compressed, and the pressure increases correspondingly. According to Pascal's principle, the increased pressure will be uniformly transmitted to all surfaces inside the cavity, including the circuit substrate 2 on the other side and all piezoresistive sensors thereon. It should be noted that this design has the following beneficial effects: first, it can equalize pressure, convert point-like and concentrated loads that may damage a single sensor into a distributed and uniform surface pressure, thereby effectively protecting the precision sensors below; second, it can buffer overload, the compressibility of gas provides a certain compliance for the fingertip, which can absorb impact energy and prevent sensors from being directly damaged by instantaneous large impact force.

[0038] The external protective layer 5, as the outermost layer of the entire tactile fingertip module, is connected to the quick-change base 1 and located outside the pressure-equalizing sealed cavity 4. As a part that directly contacts with external objects, the external protective layer 5 is usually made of a material with high wear resistance and appropriate friction coefficient, such as thermoplastic polyurethane (TPU). Its shape completely fits the three-dimensional curved surface of the pressure-equalizing sealed cavity 4, and the two together constitute the final shape of the fingertip. It can be understood that when the external protective layer 5 is worn out due to long-term use, in view of the replaceable characteristic of the entire tactile fingertip module, a user can quickly replace it with a brand-new module without repairing the complicated internal structure.

[0039] A surface contact force calculation method matching the above quick-change tactile fingertip is elaborated in detail below. The method can be executed by an algorithm deployed in a robot main controller or a microprocessor inside the fingertip, and its purpose is to accurately invert the contact position and contact force acting on the three-dimensional curved surface of the fingertip according to the discrete readings of the sensor array.

[0040] The method specifically includes the following steps: Step S101: Pressure calibration and nodal load calculation.

[0041] As an initial link of data processing, the controller collects the original signals output by each piezoresistive sensor on the circuit substrate 2 in real time through the signal conductive contacts, and the signal is usually a voltage value (in (N=8 in this embodiment, serving as the index for the sensor). Considering that the characteristics of each sensor chip may have slight differences, a pre-determined calibration function is required. Calibrate each sensor and record the voltage value of each sensor. Convert to the corresponding pressure value ,Right now ,in These are calibration coefficients for the sensor's sensitivity, zero-point offset, etc. To eliminate baseline drift caused by factors such as ambient temperature and initial assembly stress, it is necessary to obtain the initial pressure reading under no-load conditions. For each valid measurement, record the current pressure reading. Subtracting the initial value yields the net change in pressure caused by the external contact force. The operation of maximizing the value aims to ignore possible negative drift. Finally, the pressure change of each sensor is... Multiplied by its effective pressure-bearing area on circuit board 2 The equivalent nodal load at the sensor location can then be obtained. It is understandable that the load at this node can be considered as the normal force borne by the sensor unit.

[0042] Step S102: Calculate the two-dimensional pressure center.

[0043] Obtain the node loads of all sensors Next, this step aims to calculate the point of application of the resultant force of these discrete loads on the two-dimensional plane of the circuit board 2, i.e., the two-dimensional pressure center. The calculation method involves a weighted average of the position coordinates of all sensors, with the weights representing the nodal loads of each sensor. Specifically, suppose the first The planar coordinates of the sensors in the coordinate system of circuit board 2 are: This coordinate is a fixed parameter determined by the sensor layout. First, calculate the total load. If the total load Less than or equal to the preset contact detection threshold If the value is less than the threshold, it can be determined that there is no effective contact, and the algorithm terminates; otherwise, if it is greater than the threshold, the coordinates of the two-dimensional pressure center are determined. It can be calculated using the following formula:

[0044]

[0045] It can be considered that the two-dimensional pressure center is the projection center of the external contact force on the sensor substrate plane.

[0046] Step S103: Map the three-dimensional contact position.

[0047] This step maps the two-dimensional pressure center calculated in the previous step onto the three-dimensional surface of the fingertip to determine the actual contact point location. This process requires prior acquisition of the geometric equation of the three-dimensional surface at the tip of the fingertip, which can be expressed as: It can be precisely calibrated through computer-aided design models at the fingertips or 3D scanning. The coordinates of the two-dimensional pressure center are... Substituting into this geometric equation, we can obtain the coordinates of the three-dimensional contact point on the z-axis. Therefore, the contact point in the three-dimensional coordinate system of the fingertip , This represents the vector transpose. Accordingly, for subsequent force direction calculations, the surface normal vector at the contact point also needs to be calculated. For equations... The defined surface, at point A normal vector at a location The calculation method is as follows:

[0048] in, f x ( ), f y ( ) represents the partial derivative of the three-dimensional surface.

[0049] Step S104: Calculate the total normal contact force.

[0050] It should be noted that this step aims to assess the total load. Compensation calculations are performed to obtain the true total normal contact force acting at the three-dimensional contact point. This is because directly using the total load... The total normal contact force is inaccurate because it does not take into account the physical properties of the force transmission medium (gas in this embodiment) and the external protective layer 5 itself. In this embodiment, the compensation calculation can be based on the physical models of the force transmission medium and the external protective layer 5. Specifically, it can include, but is not limited to, the following two compensations: First, compensation based on the gas compression model. When the deformable airbag is compressed, its internal gas pressure increases, and the total normal contact force... A portion of it is used to overcome gas pressure. This portion of the force is related to the total load measured by the sensor. There exists a proportional relationship between them, which can be expressed as: ,in It is a pressure transmission calibration coefficient obtained through experimental calibration. Secondly, compensation is based on the elastic model of the outer protective layer 5. When the fingertip contacts the object, the outer protective layer 5 itself also undergoes elastic deformation. δThis represents the equivalent normal displacement of the outer protective layer. According to Hooke's Law, this deformation will generate an elastic restoring force with a magnitude of... ,in This is the equivalent normal stiffness of the external protective layer. Taking all the above factors into account, the total normal contact force... It can be modeled as:

[0051] Among them, deformation Based on the average pressure increment The gas is estimated using the equation of state (such as the ideal gas law or the equation of adiabatic process) and the geometric parameters of the cavity.

[0052] First, calculate the area-weighted average pressure increment measured by the sensor array:

[0053] Based on the adiabatic compression relationship of gases, the volume compression of the airbag Equivalent normal displacement of the outer protective layer for:

[0054]

[0055] The adiabatic index of the gas. This represents the initial volume of the airbag. This is the initial absolute pressure. This represents the equivalent compression area of ​​the curved surface. Through this compensation calculation, the specific total load can be obtained. More accurate total normal contact force .

[0056] (1) Calibration system setup and testing conditions The fully assembled tactile fingertip module was fixed onto the mechanical calibration stage base, which was equipped with a high-precision force sensor and a micro-stepping displacement stage. A rigid hemispherical indenter was selected for calibration, its diameter matched to the size of the fingertip's sensitive area. The calibration experiment was conducted at a constant standard room temperature to eliminate the interference of temperature differences on the initial physical state of the force-transmitting medium within the cavity.

[0057] (2) Loading range and data acquisition A control displacement stage drives a rigid indenter, applying a vertical downward load along the normal direction from the sensitive feature point of the three-dimensional curved surface at the fingertip. The loading process employs a quasi-static low-speed displacement control method, keeping the loading speed within a preset quasi-static slow-speed threshold to eliminate hysteresis. The normal load range is set according to the target force measurement range (0-20N) for the actual operation. During loading, the calibration stage records the actual standard normal force in real time. Simultaneously, the tactile fingertip module records the total load measured by the sensor array. The equivalent displacement is calculated based on the current structural parameters. The experiment was repeated multiple times, and the collected sequence data were resampled and averaged according to the displacement step size to construct a calibration dataset for fitting.

[0058] (3) Data processing methods and fitting formulas Based on physical model The experimental collection M Group sample data pairs As the independent variable, the true normal force As the target variable (where Construct a multivariate linear optimization objective function based on the least squares criterion:

[0059] Define observation matrix With standard force vector They are respectively:

[0060] Using standard least squares estimation, the parameter vector to be calibrated The analytical solution is directly expressed as:

[0061] By performing the linear regression calculations described above, the calibration constants corresponding to the current tactile fingertip structure and material configuration can be uniquely determined. This is pre-embedded in the controller to achieve real-time calculation of normal contact forces. For different physical media or soft structure variants, the same quasi-static loading and least squares fitting process described above can be followed to complete the general calibration.

[0062] Step S105: Determine the three-dimensional normal contact force vector.

[0063] In obtaining the total normal contact force (Scalar) and the normal vector at the point of contact After (vector) analysis, this step combines the two to determine the final three-dimensional contact force. (Vector). It is understandable that, due to... This is the total normal contact force acting on the surface of the fingertip, and its direction is opposite to the direction of the surface normal (the force is applied to the surface, while the normal vector is usually defined as pointing outwards from the surface). Therefore, the three-dimensional normal contact force vector can be expressed as:

[0064] normal vector Substituting these values, we can obtain the components of the contact force along the X, Y, and Z coordinate axes:

[0065]

[0066]

[0067] Through the above steps, the complete calculation from the underlying sensor signals to the three-dimensional contact position and three-dimensional normal contact force vector with clear physical meaning can be completed. This is used for real-time force control and closed-loop operation of the dexterous hand, thereby providing accurate tactile feedback for the robot to perform advanced tasks such as grasping and force control.

[0068] Example 2 In another embodiment, this application also provides a variation of the quick-change tactile fingertip. Compared with Embodiment 1, the main difference of this embodiment lies in the specific implementation of the mechanical quick-lock structure, which aims to provide a quick-change solution with a more robust connection under certain specific working conditions (such as environments with high vibration or strong magnetic field interference).

[0069] In this embodiment, the mechanical quick-lock structure between the quick-change base 1 of the tactile fingertip module and the fingertip of the dexterous hand adopts a snap-fit ​​connection structure instead of the magnetic connection structure in Embodiment 1. Specifically, the connecting end (tail) of the quick-change base 1 can be designed as a cylindrical interface with annular or dotted snap-fit ​​grooves. Correspondingly, the docking interface of the fingertip of the dexterous hand can be designed as a hollow sleeve with one or more radially retractable spring pins inside.

[0070] During installation, the operator simply pushes the cylindrical interface of the fingertip into the sleeve at the fingertip. When fully inserted, the side wall of the interface compresses a spring-loaded locking pin, causing it to retract inwards. After passing the pin, the spring-loaded pin automatically pops out under spring force and engages in the locking groove, usually accompanied by a crisp "click" sound to indicate that it is locked in place. This mechanical interlocking structure provides extremely high connection reliability, resisting significant tension, torque, and vibration, thus ensuring that the fingertip will not accidentally detach during vigorous activity.

[0071] During disassembly, this snap-fit ​​connection structure is typically equipped with a convenient unlocking mechanism. A release button can be provided. When this release button is pressed, an internal linkage mechanism (such as a ramp or lever) forces the spring-loaded pin back into its position within the sleeve, disengaging it from the snap-fit ​​groove. At this point, the operator can easily pull out the tactile fingertip module.

[0072] It should be noted that, except for the specific form of the mechanical quick-lock structure, the other structures in this embodiment, including but not limited to the structure, materials and functions of the signal conductive contacts, circuit board 2, sensor array 3, pressure equalization sealing cavity 4 and external protective layer 5, can be the same as the scheme in Embodiment 1.

[0073] Accordingly, the surface contact force calculation method used in this embodiment can be exactly the same as the five steps (S101 to S105) described in Embodiment 1. This is because the change in the mechanical implementation of the quick-connect connection does not affect the inherent logic and physical model of tactile perception and force calculation. Through the snap-on quick-connect solution provided in this embodiment, the quick-connect tactile fingertip of this application can adapt to more demanding industrial application environments, providing users with flexibility in choosing between convenience and connection strength.

[0074] In the description of this application, it should be understood that the terms "upper", "lower", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this application.

[0075] Specific embodiments of the present invention have been described above. It should be understood that the present invention is not limited to the specific embodiments described above, and those skilled in the art can make various changes or modifications within the scope of the claims, which do not affect the essence of the present invention. Unless otherwise specified, the embodiments and features described in this application can be arbitrarily combined with each other.

Claims

1. A method for calculating the surface contact force of a robot dexterous hand, characterized in that, The surface contact force calculation method for the robotic dexterous hand, applied to tactile fingertips with quick-change bases, includes: The nodal load of each sensor is calculated based on the readings of the sensor array in the tactile fingertip. The total load is obtained by summing the nodal loads of each sensing unit. Based on the position of each sensing unit and the corresponding nodal load, the two-dimensional pressure center on the sensing base surface is calculated. Based on the geometric equation of the three-dimensional curved surface of the tactile fingertip, the two-dimensional pressure center is mapped onto the three-dimensional curved surface to determine the position of the three-dimensional contact point and calculate the normal vector at the three-dimensional contact point; Based on the physical model of the force transmission medium, the total load is compensated and calculated to obtain the total normal contact force acting on the three-dimensional contact point. The three-dimensional normal contact force vector is determined based on the normal vector and the total normal contact force.

2. The method for calculating the surface contact force of a robot dexterous hand according to claim 1, characterized in that, Through a pre-determined calibration function Calibrate each sensor, i=1, 2…N, where N is the number of sensors, and record the voltage value of each sensor. Convert to the corresponding pressure value , ,in Let be the calibration coefficient for the i-th sensor; Obtain the initial pressure reading under no-load conditions. The current pressure reading Subtract the initial pressure reading The net change in pressure caused by the external contact force is obtained. ; The pressure change of each sensor Multiplied by the effective pressure-bearing area on the circuit board The equivalent nodal load at the sensor location is obtained. , The total load for: .

3. The method for calculating the surface contact force of a robot dexterous hand according to claim 2, characterized in that, The coordinates of the two-dimensional pressure center for: Will Mapping to a 3D surface The coordinates of the three-dimensional contact point on the z-axis are obtained from the above. 3D contact point The location is: Indicates vector transpose; Calculate the three-dimensional contact point normal vector : in, f x ( ), f y ( ) represents the partial derivative of the three-dimensional surface.

4. The method for calculating the surface contact force of a robot dexterous hand according to claim 3, characterized in that, Medium force transmission term With protective layer elasticity Together they constitute the total normal contact force F N : β This is the pressure transmission calibration coefficient. For the equivalent normal stiffness of the external protective layer, δ This represents the equivalent normal displacement of the external protective layer. Define normal vector n c Pointing outwards from the curved surface, the three-dimensional contact force acts on the fingertip. F 3D for: The components of the three-dimensional contact force are: in, , , Normal vector n c The amount.

5. The method for calculating the surface contact force of a robot dexterous hand according to claim 1, characterized in that, The surface contact force calculation method further includes: performing elastic deformation compensation on the three-dimensional normal contact force vector based on the elastic model of the outer protective layer of the tactile fingertip.

6. A tactile fingertip for a robotic dexterous hand, characterized in that, include: Quick-change base, detachably connectable to the fingertips of a dexterous hand; A sensor array is mounted on the quick-change base; The controller is configured to perform the surface contact force calculation method for the robot dexterous hand as described in any one of claims 1 to 5.

7. The tactile fingertip of the robot dexterous hand according to claim 6, characterized in that, The quick-change base includes a quick-change connector that is detachably connected to the fingertips of a dexterous hand. The quick-change connector includes a mechanical quick-lock structure and signal conductive contacts.

8. The tactile fingertip of the robot dexterous hand according to claim 7, characterized in that, The mechanical quick-lock structure includes a magnetic connection structure or a snap-lock connection structure.

9. The tactile fingertip of the robot dexterous hand according to claim 6, characterized in that, It also includes a pressure equalization sealing cavity located on the side where the sensor array is located. The pressure equalization sealing cavity contains a force transmission medium for transmitting the external contact force acting on the pressure equalization sealing cavity to the sensor array.

10. The tactile fingertip of the robotic dexterous hand according to claim 9, characterized in that, It also includes an external protective layer, which is connected to the quick-change base and located outside the pressure equalization and sealing cavity.

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