A three-dimensional force sensing mechanical finger

Abstract

The present invention relates to the field of manipulator technology, and discloses a three-dimensional force sensing manipulator finger, including a manipulator finger body, characterized in that it also includes a sensing module flexibly packaged inside the fingertip of the manipulator finger body; the sensing module, from the inside of the fingertip to the surface of the manipulator finger body, includes a flexible printed circuit board, a force sensitive chip, a packaging shell and an elastic force transmission layer in sequence; a center hole is provided on the force sensitive chip, and a side thereof away from the flexible printed circuit board is evenly provided with a plurality of varistors in a circular shape; the resistance of the varistors changes accordingly with the pressure borne on the manipulator finger body, so as to obtain the load size based on the initial resistance value and resistance change value of the plurality of varistors, and obtain the sliding direction of the object based on the occurrence time of the resistance mutation of the plurality of varistors. The present invention realizes the accurate quantification and sliding recognition of the fingertip pressure, improves the accuracy and sensitivity of the human-computer interaction, and ensures the safety of the manipulator grasping action.

Description

Technical Field

[0001] The present invention relates to the technical field of manipulators, and in particular to a three-dimensional force sensing manipulator finger. Background Art

[0002] Humanoid robots have broad application prospects. They have a high degree of autonomy and reliability, can independently perform given tasks, can achieve good human-computer interaction, imitate human activities and complete complex tasks on behalf of humans. However, at this stage, the tactile perception function of the fingertips of bionic robots is still immature, the force perception in contact with the outside world is not accurate enough, and it is impossible to judge the slippage of objects in contact with the fingertips. In some cases, incomplete and inaccurate environmental parameters may be transmitted back, resulting in misjudgment and unnecessary losses. Therefore, various parties have carried out research on the force perception function of dexterous fingertips. Such devices can accurately sense the force applied to the fingers through sensors in order to realize the operation behavior of humanoid robots. This technology can greatly improve the force perception ability of fingertips and greatly enhance the development of humanoid robots.

[0003] Most current studies use the method of pasting flexible sensors on the surface of fingertips to achieve force sensing. However, flexible sensors lack a standard manufacturing process and have poor manufacturing consistency. At the same time, since flexible sensors often use elastomers as sensitive materials, they have poor stability and low accuracy, which reduces the force sensing ability of dexterous fingertip sensors and makes the data inaccurate. At the same time, since most of its integration methods are to paste flexible sensors on the surface of fingertips, they are easily damaged by the external environment and have poor repeatability. At present, most of the force sensing of dexterous fingertips is one-dimensional force detection, which cannot sense forces in other directions and lacks multi-dimensional force perception. It is impossible to effectively and freely sense targets in complex spaces; and it is impossible to detect the slippage of objects relative to the fingertip surface, which is easy to misjudge the environment and cause losses. Summary of the invention

[0004] To this end, the technical problem to be solved by the present invention is to overcome the problems of poor repeatability and high misjudgment rate caused by the simple perception integration method and low perception dimension of the robot in the prior art.

[0005] In order to solve the above technical problems, the present invention provides a three-dimensional force sensing mechanical finger, comprising a mechanical finger body, characterized in that it also comprises a sensing module flexibly packaged inside the fingertip of the mechanical finger body; the sensing module, from the inside to the surface of the mechanical finger body, comprises:

[0006] Flexible printed circuit boards;

[0007] A force-sensitive chip, wherein the metal pins of the force-sensitive chip are electrically connected to the flexible printed circuit board, and the body of the force-sensitive chip is provided with a central hole; a plurality of piezoresistors are evenly arranged in a circular shape on one side of the force-sensitive chip away from the flexible printed circuit board; the resistance of the piezoresistors changes accordingly with the pressure on the body of the mechanical finger, so as to obtain the load size based on the initial resistance values ​​and resistance change values ​​of the plurality of piezoresistors, and obtain the sliding direction of the object based on the occurrence time of the resistance mutation of the plurality of piezoresistors;

[0008] The packaging shell is a hollow rectangular layer with one side without a bottom, the bottomless side is fixed on the flexible printed circuit board, forming a cavity for placing the force-sensitive chip, and its height is not less than the height of the force-sensitive chip; the bottomed side is provided with a central through hole concentric with the central hole of the force-sensitive chip;

[0009] The elastic force transmission layer is a rectangular layer, one side of which is provided with a cylindrical protruding central axis matching the central through hole of the packaging shell, and the central axis contacts the force sensitive chip through the central through hole.

[0010] Preferably, when the number of varistors is 4, the 4 varistors are evenly arranged in a circle on a side of the force sensitive chip away from the flexible printed circuit board in the following manner: they are respectively arranged in the east direction, south direction, west direction and north direction of the center hole of the force sensitive chip.

[0011] Preferably, the load magnitude is obtained based on the initial resistance values ​​and resistance change values ​​of a plurality of varistors, including:

[0012] Based on the west direction due east direction The initial resistance and resistance change of the varistor are calculated by the load Size in the axis direction , expressed as: ;

[0013] Based on true north With due south The initial resistance and resistance change of the varistor are calculated by the load Size in the axis direction , expressed as: ;

[0014] Based on the west direction , due east , due north With due south The initial resistance and resistance change of the varistor are calculated by the load Size in the axis direction , expressed as: ;

[0015] Based on the load axis, Axis and The size in the axial direction and the 3rd-order calibration matrix are used to calculate the load size , expressed as: ;

[0016] in, , , and Respectively represent the initial resistance values ​​of the varistor in the due west, due east, due north and due south directions; , , and Respectively represent the resistance change of the varistor in the due west, due east, due north and due south directions; The third-order calibration matrix represents the linear relationship between the three-dimensional orthogonal force components of the load and the three-channel output responses of the force-sensitive chip in the robot finger body.

[0017] Preferably, the sliding direction of the object is obtained based on the occurrence time of the resistance mutation of the plurality of varistors, including sorting the plurality of varistors from early to late based on the occurrence time of the resistance mutation of the plurality of varistors:

[0018] If the sorted order is the piezoresistors in the due north direction, the piezoresistors in the due east direction and the due west direction at the same time, and the piezoresistors in the due south direction, then the sliding direction of the object is from north to south;

[0019] If the sorted order is the south direction varistor, the east direction varistor and the west direction varistor at the same time, and the north direction varistor, then the sliding direction of the object is from south to north;

[0020] If the sorted order is the piezoresistance in the due east direction, the piezoresistance in the due south direction and the piezoresistance in the due north direction at the same time, and the piezoresistance in the due west direction, then the sliding direction of the object is from east to west;

[0021] If the sorted order is the varistor in the due west direction, the varistor in the due south direction and the varistor in the due north direction at the same time, and the varistor in the due east direction, the sliding direction of the object is from west to east.

[0022] Preferably, the sensing module and the mechanical finger body, the flexible printed circuit board and the packaging shell, and the packaging shell and the elastic force transmission layer are all bonded and fixed by using colloid.

[0023] Preferably, the colloid is silica gel 734, Kraft or 502.

[0024] Preferably, a wire bonding machine is used to electrically connect the metal pins on the force sensitive chip with corresponding metal pins on the flexible printed circuit board.

[0025] Preferably, photolithography technology and ion implantation methods are used to implant preset ions into multiple preset positions on a pre-treated SOI silicon wafer, and after multiple varistors are generated, the SOI silicon wafer is metal-plated to generate a force-sensitive chip.

[0026] Preferably, a central axis hole is etched on the front surface of the silicon wafer, and polydimethylsiloxane of a preset thickness is spin-coated on the surface of the silicon wafer using a rotary coating method. After the polydimethylsiloxane solidifies, it is removed to serve as an elastic force transmission layer with a central axis having a cylindrical protrusion on one side.

[0027] Preferably, a filling layer is also included to fill the gap between the sensing module flexibly packaged inside the fingertip of the mechanical finger body and the mechanical finger body.

[0028] The above technical solution of the present invention has the following beneficial effects compared with the prior art:

[0029] The three-dimensional force-sensing mechanical finger described in the present invention sets a force-sensitive chip including a plurality of piezoresistors arranged in a preset order on a flexible printed circuit board and protects it with a packaging shell. After sensing the external pressure with an elastic force transmission layer, the external pressure is transmitted to the force-sensitive chip through a central axis and a central through hole, so that the resistance value of the piezoresistors changes, so as to identify the size of the external load and the sliding direction based on the change in resistance value. The present invention arranges a plurality of piezoresistors in a circle on a force-sensitive chip, calculates the magnitude of the force of the load in different directions based on the initial resistance values ​​and resistance change values ​​of the piezoresistors arranged in different directions, realizes the accurate quantification of the fingertip pressure, realizes the perception of the magnitude of the force in three dimensions of the external pressure, and improves the accuracy and reliability of the pressure magnitude recognition; and based on the occurrence time of the resistance mutation of the piezoresistors arranged in different directions, judges the movement direction of the contact point between the fingertip and the object, and then obtains the sliding direction of the object perceived by the fingertip, which helps to improve the accuracy and sensitivity of human-computer interaction and ensure the safety of the gripping action of the manipulator; at the same time, the packaging shell is used to protect the force-sensitive chip from being damaged, and the central axis of the elastic force sensing layer is used to transmit the force information to the force-sensitive chip for identification, which ensures that the force-sensitive chip is not disturbed by the external environment, thereby improving the measurement accuracy, and realizing the real-time measurement of the external pressure, with high precision, low latency and a large range. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] In order to make the content of the present invention more clearly understood, the present invention is further described in detail below according to specific embodiments of the present invention in conjunction with the accompanying drawings, wherein:

[0031] Figure 1 It is a schematic diagram of the module explosion of the three-dimensional force sensing mechanical finger provided by the present invention;

[0032] Figure 2 is a schematic diagram of a perception module provided by the present invention;

[0033] Figure 3 It is an exploded diagram of the perception module provided by the present invention;

[0034] Figure 4 It is a schematic diagram of the connection relationship between the sensing module and the mechanical finger provided by the present invention;

[0035] Figure 5 is a schematic structural diagram of a force-sensitive chip when the number of varistors provided by the present invention is 4;

[0036] Figure 6 It is a schematic diagram of slip direction identification provided by the present invention;

[0037] Figure 7 is a schematic diagram of a packaging shell provided by the present invention;

[0038] Figure 8 is a schematic diagram of the structure of the elastic force transmission layer provided by the present invention;

[0039] Fig. 9 is a schematic diagram of a flexible printed circuit board provided by the present invention;

[0040] Explanation of the markings in the specification: 1. Mechanical finger body; 2. Sensing module; 3. Flexible printed circuit board; 4. Force sensitive chip; 5. Center hole; 6. Varistor; 7. Packaging shell; 8. Center through hole; 9. Elastic force transmission layer; 10. Center axis. DETAILED DESCRIPTION

[0041] The present invention is further described below in conjunction with the accompanying drawings and specific embodiments so that those skilled in the art can better understand the present invention and implement it, but the embodiments are not intended to limit the present invention.

[0042] Reference Figure 1 As shown, the exploded schematic diagram of the module of the three-dimensional force sensing mechanical finger provided by the present invention specifically includes a mechanical finger body 1, and also includes a sensing module 2 flexibly packaged inside the fingertip of the mechanical finger body; the sensing module, from the inside of the fingertip of the mechanical finger body to the surface, includes:

[0043] Flexible printed circuit board 3;

[0044] A force-sensitive chip 4, whose metal pins are electrically connected to the flexible printed circuit board, and whose body is provided with a central hole 5; a plurality of piezoresistors 6 are evenly arranged in a circular shape on one side away from the flexible printed circuit board; the resistance of the piezoresistors changes accordingly with the pressure on the robot finger body, so as to obtain the load size based on the initial resistance values ​​and resistance change values ​​of the plurality of piezoresistors, and obtain the sliding direction of the object based on the occurrence time of the resistance mutation of the plurality of piezoresistors;

[0045] The packaging shell 7 is a hollow rectangular layer with one side without a bottom, the bottomless side is fixed on the flexible printed circuit board, forming a cavity for placing the force-sensitive chip, and its height is not less than the height of the force-sensitive chip; the bottomed side is provided with a central through hole 8 concentric with the central hole of the force-sensitive chip;

[0046] The elastic force transmission layer 9 is a rectangular layer, one side of which is provided with a cylindrical protruding central axis 10 matching the central through hole of the packaging shell, and the central axis contacts the force sensitive chip through the central through hole.

[0047] Reference Figure 2 As shown, it is a schematic diagram of the perception module; Figure 3 As shown, it is an exploded diagram of the perception module; refer to Figure 4 As shown, it is a schematic diagram of the connection relationship between the sensing module and the robotic finger; a cavity is left inside the robotic finger, and the flexible printed circuit board (FPCB) passes through the cavity from the tail of the finger so that it can be connected to the control center of the robotic finger for data transmission.

[0048] After the MEMS three-dimensional force sensor based on the piezoresistive principle is integrated with the dexterous finger, the present invention can accurately and effectively realize the three-dimensional force perception of the fingertips of the humanoid robot. By detecting the slippage of the object relative to the fingertips, the dexterous hand can grasp the object more stably. Among them, the three-dimensional force information of the fingertips can be obtained by the resistance change of the piezoresistive resistance sensing chip; the slippage of the object relative to the fingertips can be identified by the different order of the resistance mutation of the four piezoresistors in the timing sequence, and finally realize the accurate detection of the three-dimensional force of the fingertips and stable grasping during the working process of the humanoid robot.

[0049] In this embodiment, the preset ions are implanted into multiple preset positions on the pre-treated SOI silicon wafer to generate multiple varistors, and then the SOI silicon wafer is metal-plated to generate a force-sensitive chip. Figure 5As shown, it is a schematic diagram of the structure of the force-sensitive chip when the number of varistors is 4; A0, A1, A2 and A3 are four varistors, and the force-sensitive chip is made by using MEMS silicon micromachining technology on SOI silicon wafers using ion implantation technology combined with metal plating, etching, and deep reactive ion etching technology. When the number of varistors is 4, the 4 varistors are evenly arranged in a circular shape on the side of the force-sensitive chip away from the flexible printed circuit board. The arrangement method is: they are respectively arranged in the east direction E, south direction S, west direction W and north direction N of the center hole of the force-sensitive chip.

[0050] When the tip of the robot finger is subjected to an external load, the external load is transmitted to the package shell and the force-sensitive chip through the deformation of the elastic force transmission layer. The package shell can reduce the force on the force-sensitive chip, thereby protecting the fragile silicon-based bridge structure; the load on the force-sensitive chip causes the resistance of the piezoresistors on it to change, generating an electrical signal output, thereby realizing pressure detection. When the normal load acts, the four bridges are compressed and deformed under the action of the external load, causing the four piezoresistors to undergo similar deformations. The magnitude of the normal load can be calculated by the average value of the resistance change of the four piezoresistors. When the tangential load acts, torsion occurs around the central column, causing micro-rotation on the surface of the elastic layer; therefore, the strains of the two piezoresistive bridges along the shear force direction are different, and the magnitude of the tangential force can be determined based on the difference in the resistance change of the two bridges in the tangential force direction, thereby realizing the detection of three-dimensional forces (normal force and tangential force).

[0051] Based on the above description, this embodiment obtains the load size based on the initial resistance values ​​and resistance change values ​​of multiple varistors, including:

[0052] S1: Based on the west direction due east direction The initial resistance and resistance change of the varistor are calculated by the load Size in the axis direction , expressed as: ;

[0053] S2: Based on the true north direction With due south The initial resistance and resistance change of the varistor are calculated by the load Size in the axis direction , expressed as: ;

[0054] S3: Based on the west direction , due east , due north With due south The initial resistance and resistance change of the varistor are calculated by the load Size in the axis direction , expressed as: ;

[0055] S4: Based on the load axis, Axis and The size in the axial direction and the 3rd-order calibration matrix are used to calculate the load size , expressed as: ;

[0056] in, , , and Respectively represent the initial resistance values ​​of the varistor in the due west, due east, due north and due south directions; , , and Respectively represent the resistance change of the varistor in the due west, due east, due north and due south directions; A third-order calibration matrix is ​​provided to describe the linear relationship between the three-dimensional orthogonal force components of the load and the three-channel output responses of the force-sensitive chip in the robot finger body. The third-order calibration matrix is ​​obtained after calibrating the force-sensitive chip.

[0057] When slip occurs, the motion state between the sensor and the external object changes from relative stillness to relative movement. The relative movement causes the bridge to vibrate, thereby causing the varistor signal to change. By comparing the voltage signal change pattern before and after the time, the occurrence of slip can be identified. Based on the above setting, this embodiment obtains the slip direction of the object based on the occurrence time of the resistance mutation of multiple varistors, including sorting the multiple varistors from early to late based on the occurrence time of the resistance mutation of multiple varistors:

[0058] If the sorted order is the piezoresistors in the due north direction, the piezoresistors in the due east direction and the due west direction at the same time, and the piezoresistors in the due south direction, then the sliding direction of the object is from north to south;

[0059] If the sorted order is the south direction varistor, the east direction varistor and the west direction varistor at the same time, and the north direction varistor, then the sliding direction of the object is from south to north;

[0060] If the sorted order is the piezoresistance in the due east direction, the piezoresistance in the due south direction and the piezoresistance in the due north direction at the same time, and the piezoresistance in the due west direction, then the sliding direction of the object is from east to west;

[0061] If the sorted order is the varistor in the due west direction, the varistor in the due south direction and the varistor in the due north direction at the same time, and the varistor in the due east direction, the sliding direction of the object is from west to east.

[0062] Specifically, as the number of piezoresistors provided on the force-sensitive chip increases, the sliding trajectory of the object can be mapped out through the time when the resistance mutations of the multiple piezoresistors occur, thereby enabling more and more accurate identification of sliding directions.

[0063] Reference Figure 6 As shown in the figure, it is a schematic diagram of slip direction identification; A1 and A3 are piezoresistors in the due west direction W and due east direction E, respectively, and the external object is forced to slide in the direction of E. During the slip process, the relative position of the object and the bridge changes, the force degree of the bridge changes, and its deformation gradually changes. When the slip direction of the object is due east, as the tissue completely slides onto the A3 bridge, the deformation distribution of the four bridges changes: the deformation of the A1 bridge begins to decrease, and the deformation of the other three groups of bridges increases. When the edge of the object passes A1, A1 is only affected by the vibration signal during the slip process and is no longer affected by external pressure. At this time, the A1 signal mutates. When the object continues to slip, A0 and A2 generate signal mutations at basically the same time. When the slip leaves A3, the A3 signal mutates until the slip ends. When slip occurs in different directions, A0, A1, A2 and A3 will all produce mutations in different orders in timing. According to the different mutation sequences of A0, A1, A2 and A3 signals, the slip and direction of the object can be determined.

[0064] The dexterous hand at the end of the humanoid robot's mechanical arm is usually used to perform various manipulation tasks, in which the precise force perception of the robot's fingertips plays a vital role. In automated production lines, medical surgery assistance, and complex service robot applications, the three-dimensional force sensor at the robot's fingertips can provide detailed data on the three-dimensional force when the robot's fingers come into contact with external objects, thereby achieving precise control of the interaction between the robot and the environment. For example, in the scene where the robot's dexterous hand grasps a water cup, the fingertips come into contact with the water cup, and the three-dimensional force acting on the water cup by the dexterous fingertips can be detected. In the process of continuously adding water to the water cup, the grasping force required by the dexterous hand continues to increase, and slippage may occur at this time. By analyzing the time when the signal changes of the four varistors in the force-sensitive chip occur, the occurrence of slippage can be determined, and then the grasping force of the dexterous hand can be controlled to ensure the safety of the grasping action.

[0065] The present invention can integrate a piezoresistive sensor (force-sensitive chip) based on a bridge structure into the fingertips of dexterous fingers to achieve accurate perception of the three-dimensional force exerted on the fingertips by the external environment, thereby improving the accuracy and safety of dexterous hand operations. At the same time, the sliding direction of an object can be determined based on the different mutation sequences of multiple piezoresistance signals, thereby improving the stability and reliability of the manipulator's grasping action. This embodiment can be applied to the manipulator of a humanoid robot, allowing the humanoid robot to have a more accurate force perception function, and to control mechanical behavior according to fingertip force in complex environments, and can be applied to a variety of human-computer interaction scenarios.

[0066] In this embodiment, the sensing module and the mechanical finger body, the flexible printed circuit board and the packaging shell, and the packaging shell and the elastic force transmission layer are all bonded and fixed by colloid. The colloid is silica gel 734, Kraft or 502. Silicone 734 is a highly elastic, high and low temperature resistant, aging resistant silica gel material with excellent adhesion and sealing properties. It can maintain stable performance in a wide temperature range and is very suitable for pasting sensing modules that need to withstand certain deformation and stress. Kraft glue is a multi-purpose industrial-grade adhesive with the characteristics of fast curing, high strength, and chemical corrosion resistance. It can form a strong bond in a short time and is not easily affected by environmental factors after curing, ensuring the stability of the sensing module on the mechanical finger. 502 glue is an instant curing adhesive with the characteristics of fast curing, high strength, and easy operation. It can form a strong bond in a very short time, and can quickly fix the sensing module to the simulated finger to improve work efficiency.

[0067] Reference Figure 7 As shown, it is a schematic diagram of the packaging shell; the central through hole in the middle of the packaging shell is concentric with the central hole of the force sensitive chip, which can protect the leads of the force sensitive layer from being damaged.

[0068] Reference Figure 8 The figure shows a schematic diagram of the structure of the elastic force transmission layer; specifically, a central axis hole is etched on the front surface of the silicon wafer, and polydimethylsiloxane with a preset thickness is spin-coated on the surface of the silicon wafer by a spin-coating method. After the polydimethylsiloxane solidifies, it is removed to form an elastic force transmission layer with a central axis with a cylindrical protrusion on one side. The central axis of the elastic force transmission layer is adapted to the central through hole of the packaging shell so as to contact the force sensitive chip through the central through hole and transmit the sensed external pressure to the force sensitive chip.

[0069] Specifically, the elastic force transmission layer can be made of PDMS (polydimethylsiloxane) or other silicone rubber materials, but because PDMS is a bio-friendly material with low cost and easy processing, PDMS is selected as the elastic force transmission layer material. The processing of the elastic force transmission layer requires the preparation of a reverse mold first, mainly by wet etching / dry etching to etch a central fixed axis hole on the front surface of the silicon wafer; and then a certain thickness of PDMS (polydimethylsiloxane) is spin-coated on its surface by the method of rotating coating, and the PDMS is removed after solidification to form an elastic force transmission layer.

[0070] Specifically, the three-dimensional force sensing mechanical finger of this embodiment further includes a filling layer for filling the gap between the sensing module flexibly encapsulated inside the fingertip of the mechanical finger body and the mechanical finger body. The present invention uses polydimethylsiloxane as a filling layer to fill the fingertip of the mechanical finger body to protect the sensing module from being affected by the external environment, thereby increasing the service life of the mechanical finger.

[0071] Reference Fig. 9 , which is a schematic diagram of a flexible printed circuit board; in this embodiment, a wire bonding machine is used to electrically connect the metal pins on the force sensitive chip with the corresponding metal pins on the flexible printed circuit board.

[0072] Based on the above description, the flexible printed circuit board FPCB contains metal wires, and the surface is covered with an insulating layer to protect the metal wires from environmental factors such as liquids. There are 8 pins at the end, which is convenient for collecting sensor signals outside the finger. The force-sensitive chip is connected to the flexible PCB through wires, and the metal pins of the sensor chip are electrically connected to the corresponding points on the flexible PCB through wires with the help of a wire bonding machine. The encapsulation shell is prepared by machining and fixed to the surface of the force-sensitive chip to protect the leads of the chip from being damaged. The center through hole is concentric with the center hole of the force-sensitive chip. The elastic force transmission layer of the sensor is bonded to the encapsulation shell through silicone 734, and the raised cylinder on its lower surface contacts the force-sensitive chip through the center through hole of the encapsulation shell, which can transmit force information. Finally, PDMS is poured around the periphery of the perception module to fill the fingertips of the finger to protect the perception module from the external environment.

[0073] The three-dimensional force-sensing mechanical finger described in the present invention sets a force-sensitive layer including a plurality of piezoresistors arranged in a preset order on a flexible printed circuit board and protects it with a packaging shell. After sensing the external pressure with the elastic force transmission layer, the external pressure is transmitted to the force-sensitive layer through the central axis and the central through hole, so that the resistance value of the piezoresistors changes, so as to identify the size of the external load and the sliding direction based on the change in resistance value. The present invention arranges a plurality of piezoresistors in a circumferential pattern on the force-sensitive layer, and calculates the magnitude of the force of the load in different directions based on the initial resistance values ​​and resistance change values ​​of the piezoresistors arranged in different directions, thereby realizing accurate quantification of fingertip pressure, realizing perception of the magnitude of the force in three dimensions of external pressure, and improving the accuracy and reliability of pressure magnitude recognition; and based on the occurrence time of resistance mutation of the piezoresistors arranged in different directions, the moving direction of the contact point between the fingertip and the object is judged, and then the sliding direction of the object perceived by the fingertip is obtained, which helps to improve the accuracy and sensitivity of human-computer interaction and ensure the safety of the gripping action of the manipulator; at the same time, the packaging shell is used to protect the force-sensitive layer from being damaged, and the central axis of the elastic force sensing layer is used to transmit the force information to the force-sensitive chip for identification, thereby ensuring that the force-sensitive chip is not disturbed by the external environment, thereby improving the measurement accuracy, and realizing real-time measurement of external pressure, with high precision, low latency and a large range.

[0074] Those skilled in the art will appreciate that the embodiments of the present application may be provided as methods, systems, or computer program products. Therefore, the present application may adopt the form of a complete hardware embodiment, a complete software embodiment, or an embodiment combining software and hardware. Moreover, the present application may adopt the form of a computer program product implemented on one or more computer-usable storage media (including but not limited to disk storage, CD-ROM, optical storage, etc.) containing computer-usable program codes.

[0075] The present application is described with reference to the flowcharts and / or block diagrams of the methods, devices (systems), and computer program products according to the embodiments of the present application. It should be understood that each process and / or box in the flowchart and / or block diagram, as well as the combination of the processes and / or boxes in the flowchart and / or block diagram, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, a special-purpose computer, an embedded processor, or other programmable data processing device to generate a machine, so that the instructions executed by the processor of the computer or other programmable data processing device generate instructions for implementing the processes in the flowchart and / or block diagram. Figure 1 A process or multiple processes and / or boxes Figure 1 A device that provides the functions specified in a block or multiple blocks.

[0076] These computer program instructions may also be stored in a computer-readable memory capable of directing a computer or other programmable data processing device to operate in a specific manner, so that the instructions stored in the computer-readable memory produce an article of manufacture comprising an instruction device, which implements the process Figure 1 A process or multiple processes and / or boxes Figure 1 A function specified in one or more boxes.

[0077] These computer program instructions can also be loaded onto a computer or other programmable data processing device so that a series of operating steps are executed on the computer or other programmable device to produce a computer-implemented process, thereby providing instructions for implementing the process in the computer or other programmable device. Figure 1 A process or multiple processes and / or boxes Figure 1 The steps for the functions specified in one or more boxes.

[0078] Obviously, the above embodiments are merely examples for the purpose of clear explanation and are not intended to limit the implementation methods. For those skilled in the art, other different forms of changes or modifications can be made based on the above description. It is not necessary and impossible to list all the implementation methods here. The obvious changes or modifications derived therefrom are still within the scope of protection of the present invention.

Claims

1. A three-dimensional force sensing mechanical finger, comprising a mechanical finger body, characterized in that: It also includes a sensing module flexibly packaged inside the fingertip of the mechanical finger body; the sensing module, from the inside of the fingertip to the surface of the mechanical finger body, includes: Flexible printed circuit boards; A force-sensitive chip, whose metal pins are electrically connected to the flexible printed circuit board, and whose body is provided with a central hole; a plurality of piezoresistors are evenly arranged in a circular shape on one side away from the flexible printed circuit board; the resistance of the piezoresistors changes accordingly with the pressure on the body of the mechanical finger, so as to obtain the load size based on the initial resistance values ​​and resistance change values ​​of the plurality of piezoresistors, and obtain the sliding direction of the object based on the occurrence time of the resistance mutation of the plurality of piezoresistors; the force-sensitive chip adopts MEMS silicon micromachining technology, utilizes photolithography technology and ion implantation method, implants preset ions into a plurality of preset positions on a pre-treated SOI silicon wafer, generates a plurality of piezoresistors, and then metal-plates the SOI silicon wafer; The packaging shell is a hollow rectangular layer with one side without a bottom, the bottomless side is fixed on the flexible printed circuit board, forming a cavity for placing the force-sensitive chip, and its height is not less than the height of the force-sensitive chip; the bottomed side is provided with a central through hole concentric with the central hole of the force-sensitive chip; The elastic force transmission layer is a rectangular layer, one side of which is provided with a cylindrical protruding central axis matching the central through hole of the packaging shell, and the central axis contacts the force sensitive chip through the central through hole.

2. The three-dimensional force sensing mechanical finger according to claim 1, characterized in that: When the number of varistors is 4, the 4 varistors are evenly arranged in a circle on a side of the force sensitive chip away from the flexible printed circuit board. The arrangement method is: they are respectively arranged in the east direction, south direction, west direction and north direction of the center hole of the force sensitive chip.

3. The three-dimensional force sensing mechanical finger according to claim 2, characterized in that: The load size is obtained based on the initial resistance values ​​and resistance change values ​​of multiple varistors, including: Based on the west direction due east direction The initial resistance and resistance change of the varistor are calculated by the load Size in the axis direction , expressed as: ; Based on true north With due south The initial resistance and resistance change of the varistor are calculated by the load Size in the axis direction , expressed as: ; Based on the west direction , due east , due north With due south The initial resistance and resistance change of the varistor are calculated by the load Size in the axis direction , expressed as: ; Based on the load axis, Axis and The size in the axial direction and the 3rd-order calibration matrix are used to calculate the load size , expressed as: ; in, , , and Respectively represent the initial resistance values ​​of the varistor in the due west, due east, due north and due south directions; , , and Respectively represent the resistance change of the varistor in the due west, due east, due north and due south directions; The third-order calibration matrix represents the linear relationship between the three-dimensional orthogonal force components of the load and the three-channel output responses of the force-sensitive chip in the robot finger body.

4. The three-dimensional force sensing mechanical finger according to claim 2, characterized in that: The sliding direction of the object is obtained based on the occurrence time of the resistance mutation of the multiple varistors, including sorting the multiple varistors from early to late based on the occurrence time of the resistance mutation of the multiple varistors: If the sorted order is the piezoresistors in the due north direction, the piezoresistors in the due east direction and the due west direction at the same time, and the piezoresistors in the due south direction, then the sliding direction of the object is from north to south; If the sorted order is the south direction varistor, the east direction varistor and the west direction varistor at the same time, and the north direction varistor, then the sliding direction of the object is from south to north; If the sorted order is the piezoresistance in the due east direction, the piezoresistance in the due south direction and the piezoresistance in the due north direction at the same time, and the piezoresistance in the due west direction, then the sliding direction of the object is from east to west; If the sorted order is the varistor in the due west direction, the varistor in the due south direction and the varistor in the due north direction at the same time, and the varistor in the due east direction, the sliding direction of the object is from west to east.

5. The three-dimensional force sensing mechanical finger according to claim 1, characterized in that: The sensing module and the mechanical finger body, the flexible printed circuit board and the packaging shell, and the packaging shell and the elastic force transmission layer are all bonded and fixed by colloid.

6. The three-dimensional force sensing mechanical finger according to claim 5, characterized in that: The colloid is silica gel 734, Kraft or 502.

7. The three-dimensional force sensing mechanical finger according to claim 1, characterized in that: The metal pins on the force sensitive chip are electrically connected to the corresponding metal pins on the flexible printed circuit board using a wire bonding machine.

8. The three-dimensional force sensing mechanical finger according to claim 1, characterized in that: A central axis hole is etched on the front surface of the silicon wafer, and polydimethylsiloxane of a preset thickness is spin-coated on the surface of the silicon wafer using a rotary coating method. After the polydimethylsiloxane solidifies, it is removed to serve as an elastic force transmission layer with a central axis having a cylindrical protrusion on one side.

9. The three-dimensional force sensing mechanical finger according to claim 1, characterized in that: It also includes a filling layer, which is used to fill the gap between the sensing module flexibly packaged inside the fingertip of the mechanical finger body and the mechanical finger body.

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