A two-degree-of-freedom underactuated robot thumb based on a linear slide mechanism

Abstract

A kind of double-degree-of-freedom underactuated robot thumb based on linear slide rod mechanism relates to intelligent robot technical field.Base joint frame, proximal phalanx frame and distal phalanx frame are connected by metacarpophalangeal joint and interphalangeal joint to form base structure, two drivers are connected transmission screw lever at bottom, transmission link is Y-shaped structural member, two branch arms of which are hinged to the bottom end of distal phalanx frame, the main arm is provided with slide hole and slide rod to form sliding pair, the bottom end is supported by spring, the bottom end of slide rod is hinged to metacarpophalangeal joint, screw nut and screw lever are arranged on the both sides of the bottom end of transmission link to form ball screw pair, position sensor collects distal phalanx frame position signal, and magnet steel and hall sensor measure proximal phalanx frame position signal.Two degrees of freedom motion is realized by using parallel structure, stable and flexible adaptive enveloping grasping of object is realized, the overall structure is simple and efficient, and has the advantages of high integration, high power density, fast response speed and accurate measurement.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of intelligent robots, and particularly relates to a double-degree-of-freedom underactuated robot thumb based on a straight slide rod mechanism. BACKGROUND

[0002] As a core executive component for realizing fine operation and human-computer interaction, the motion flexibility, grasping stability and structural compactness of the thumb of a humanoid robot hand directly determine the work capacity of the robot hand. Among them, the thumb structure with double degrees of freedom of flexion and lateral swing becomes the key to realizing complex grasping (such as pinching and wrapping grasping) because it can simulate the core motion mode of the human thumb, and is widely used in scenes such as service robots, industrial assembly robots and rehabilitation auxiliary robots.

[0003] At present, the existing double-degree-of-freedom robot thumb cannot meet the comprehensive needs of structural integration, driving force performance, motion accuracy and grasping adaptability, mainly in the following aspects:

[0004] Insufficient structural integration and power density: the existing double-degree-of-freedom thumb mostly adopts a design mode of independent driving mechanism combined with separate transmission assembly, for example, the driving motor and transmission screw of the flexion degree of freedom and the steering motor and gear set of the lateral swing degree of freedom are arranged respectively, and the motion coupling between the mechanisms is realized through a complex bracket connection. This design leads to loose overall structure of the thumb, large number of components and high assembly complexity, which not only increases the volume and weight of the thumb, making it difficult to adapt to small robots, but also causes large power loss and low power density due to the dispersed transmission path, which easily causes insufficient driving force in the scene of grasping heavy objects or requiring fast response. In addition, some designs use a single driver to realize double-degree-of-freedom motion by cooperating with a cam, a connecting rod and other mechanisms, but this way will cause mutual coupling and interference of the motion of the two degrees of freedom, which cannot be independently and accurately controlled, limiting the operation flexibility.

[0005] Balancing contradiction between driving force and structural size: in order to meet the driving force demand of double-degree-of-freedom motion, two schemes are usually adopted at present: one is to select a high-power driver, which will directly lead to an increase in the overall size of the thumb, destroying the lightweight and compactness of the hand; the other is to use multiple drivers in series to drive, and to superimpose the output force through multi-stage transmission, but the series structure will further lengthen the transmission chain, reduce the response speed, and increase the complexity of structural layout, which is prone to motion lag when quickly switching actions.

[0006] The accuracy and reliability of angle measurement are limited: Existing MCP joint angle measurements for dual-degree-of-freedom thumbs mostly rely on indirect measurement methods. One method involves installing an encoder at the output shaft of the driver and performing coupled calculations based on the transmission ratio of the transmission mechanism to indirectly deduce the flexion, extension, and lateral swing angles of the joint. This method accumulates errors caused by transmission backlash and friction loss, and the wear of transmission components, especially after long-term use, leads to a continuous decrease in measurement accuracy. Another method involves installing multiple potentiometers or photoelectric sensors at the joint to measure the angles of the two degrees of freedom separately. However, to avoid spatial interference between the sensors and the transmission mechanism, the sensor signals need to be led out via cables. During thumb movement, the cables are prone to tangling and pulling, which not only increases the complexity of electrical wiring but may also lead to measurement failure due to cable fatigue and breakage, reducing operational reliability.

[0007] Efficiency and adaptability in the grasping process are difficult to balance: Existing robotic thumb grasping actions are mostly single-stage driven modes. They either use fully active drive (both the proximal and distal phalanges are directly driven by motors), which can precisely control the movement of each phalanx, but requires complex planning of the movement trajectory of the two phalanges, resulting in slow response speed. Furthermore, when grasping irregularly shaped objects, it is difficult to quickly adjust the phalanx posture to conform to the object surface, leading to unstable grasping. Alternatively, they use fully passive adaptive drive (the phalanges passively deform with the object shape through springs, elastic hinges, etc.), which simplifies the control logic, but the process of the proximal phalanx approaching the object relies on inertia or external thrust, resulting in low efficiency. Moreover, it cannot actively adjust the initial grasping posture, limiting the applicable scenarios.

[0008] In summary, the current shortcomings of dual-DOF robot thumbs have become a key bottleneck restricting the development of robot hands towards miniaturization, high precision, high reliability, and strong adaptability. Therefore, there is an urgent need to design a highly integrated, high-power-density dual-DOF underactuated robot thumb that can balance actuation performance, measurement accuracy, and grasping adaptability, which is of great significance for the development and application of robot hands. Summary of the Invention

[0009] To address the shortcomings of the prior art, this invention provides a dual-degree-of-freedom underactuated robot thumb based on a linear slider mechanism. Its parallel structure design enables two degrees of freedom of motion, achieving stable and compliant adaptive envelope grasping of objects. The overall structure is simple and efficient, and it also has the advantages of high integration, high power density, fast response speed, and accurate measurement.

[0010] To achieve the above objectives, the present invention adopts the following technical solution: a two-degree-of-freedom underactuated robot thumb based on a linear slider mechanism, comprising a base structure, a drive mechanism, an underactuated linkage mechanism, and a measurement mechanism;

[0011] The base structure includes a base joint frame, a proximal phalanx frame, and a distal phalanx frame. The end of the base joint frame is connected to the palm as a fixed position. The proximal phalanx frame is a transversely symmetrical double support rod structure. The end of the proximal phalanx frame is connected to the top of the base joint frame to form a metacarpophalangeal joint. The end of the distal phalanx frame is connected to the top of the proximal phalanx frame to form an interphalangeal joint.

[0012] The drive mechanism includes two drivers symmetrically fixed on both sides of the front of the bottom of the base joint frame. The output ends of the two drivers face upward and are respectively connected to the bottom ends of two screw levers through double universal joints.

[0013] The underactuated linkage mechanism includes a transmission link, a slide bar, and a spring. The transmission link is a Y-shaped structure and is inclinedly positioned at the top between the proximal and distal phalangeal joint frames. The ends of its two branch arms are hinged to the front side of the bottom end of the distal phalangeal joint frame. Its main arm is inclined to the rear and has a through-hole at its axial position. The slide bar cooperates with the slide hole to form a sliding pair. The bottom end of the slide bar is hinged to the metacarpophalangeal joint. The spring is sleeved on the slide bar and elastically supported between the bottom end of the transmission link and the hinge point of the bottom end of the slide bar. Two lead screw nuts are integrated side by side on both sides of the bottom end of the main arm of the transmission link. The bottom of both lead screw nuts is inclined to the front. The top of the two lead screw nuts cooperates with the corresponding lead screw nuts to form a ball screw pair.

[0014] The measuring mechanism includes a position sensor, a magnet, and a Hall sensor. The position sensor is installed on the side of the interphalangeal joint to collect the position signal of the distal phalanx frame. The magnet is fixed to the bottom of the proximal phalanx frame and moves synchronously with it. The Hall sensor is fixed at the center of the top of the base joint frame. The position signal of the proximal phalanx frame is measured by the cooperation of the magnet and the Hall sensor.

[0015] Furthermore, a bearing seat is integrally provided at the rear center of the top of the base joint frame for mounting and bearing the adapter. An adapter shaft arranged horizontally along the front-back direction is provided on the rear side of the adapter and is rotatably connected to the bearing seat. The adapter shaft is axially positioned by screws. A lower joint shaft is provided on the front side of the adapter along the transverse direction. The bottom end of the proximal phalanx frame is hinged to both sides of the lower joint shaft. The adapter shaft of the adapter and the lower joint shaft constitute a rotation axis with two degrees of freedom of flexion and extension and lateral swing of the metacarpophalangeal joint.

[0016] Furthermore, the bottom end of the distal phalanx frame is hinged to the top end of the proximal phalanx frame via an upper joint shaft, and the upper joint shaft constitutes the rotation axis for the flexion and extension degrees of freedom of the interphalangeal joint.

[0017] Furthermore, a pin is provided at the top of the slide rod, which provides axial limit positioning for the relative sliding of the slide rod and the transmission connecting rod.

[0018] Furthermore, in the measuring mechanism, when the proximal phalanx frame is in the middle position of flexion and extension and lateral swing, the magnet is parallel to the Hall sensor, and at this time the magnet is located at the zero position of the Hall sensor.

[0019] Furthermore, in the measuring mechanism, the position sensor is connected to a fingertip circuit board fixed on the back side of the distal phalanx frame via a connecting wire. The fingertip circuit board is connected to a Hall sensor via a connecting wire. The Hall sensor is connected to a finger root circuit board fixed on the top of the back side of the base joint frame via a connecting wire. The finger root circuit board is connected to an electromechanical interface fixed on the bottom of the back side of the base joint frame. The signal acquisition of the position sensor and the Hall sensor is realized through an external control system connected to the electromechanical interface.

[0020] Furthermore, two base joint circuit boards are symmetrically installed on both sides of the bottom of the base joint frame. The two base joint circuit boards are respectively connected to two drivers to realize the control of rotation speed and steering. The two base joint circuit boards are connected in parallel and connected to the electromechanical interface. The two drivers are dynamically controlled by an external control system through the electromechanical interface.

[0021] Furthermore, the proximal phalanx frame is fitted with a proximal phalanx shell by bolts, and the distal phalanx frame is fitted with a distal phalanx shell by bolts.

[0022] Compared with the prior art, the beneficial effects of the present invention are:

[0023] 1. The robot thumb of this invention adopts a specific structural design that integrates a double universal joint mechanism, a ball screw mechanism, and an underactuated linkage mechanism. Its core is that two actuators drive the proximal phalanx together through the double universal joint and the ball screw mechanism to achieve a composite motion of two degrees of freedom: the proximal phalanx and the lateral swing. The underactuated linkage mechanism, composed of a slide bar, a spring, and a transmission link, drives the distal phalanx to perform passive adaptive bending, forming a highly integrated and high-power-density two-degree-of-freedom thumb structure.

[0024] 2. The circuit part of the robot thumb of this invention directly measures the two-dimensional motion angle of the MCP joint through the cooperation of magnets and Hall sensors, which simplifies the electrical wiring in the mechanical structure, avoids cable tangling, and helps to reduce the angle error caused by indirect measurement and coupled calculation.

[0025] 3. The gripping action of the robot thumb in this invention is divided into two continuous stages: the first stage is active bending, in which the proximal phalanx is driven by a ball screw mechanism to move rapidly to approach and initially wrap around the object to be gripped; the second stage is passive adaptation, in which when the proximal phalanx is obstructed, the power is transmitted through an underactuated linkage mechanism, causing the distal phalanx to bend passively until it fits against the surface of the object to be gripped, and finally forming a stable and compliant envelope gripping, thus achieving a unity of high efficiency and adaptability in the thumb gripping process.

[0026] 4. The power for the two degrees of freedom of the thumb MCP joint of the robot of the present invention is provided by two actuators in parallel, so that the output force for each degree of freedom can be nearly twice that without changing the size of the actuators and transmission mechanism, thus achieving a significant reduction in the overall size of the thumb without reducing the output force. Attached Figure Description

[0027] Figure 1 This is a front view schematic diagram of the robot thumb of the present invention; the phalanx shell is not shown.

[0028] Figure 2 yes Figure 1 The right-side view;

[0029] Figure 3 yes Figure 1 Rear view;

[0030] Figure 4 This is a schematic diagram showing the initial positional relationship between the magnet and the Hall sensor in the machine of this invention;

[0031] Figure 5 This is a schematic diagram of the appearance of the robot's thumb according to the present invention.

[0032] In the diagram: 101. Driver 1; 102. Driver 2; 103. Base joint frame; 104. Double universal joint 1; 105. Double universal joint 2; 106. Slide rod; 107. Lever 1; 108. Lever 2; 109. Spring; 110. Transmission link; 111. Proximal joint frame; 112. Pin; 113. Upper pivot; 114. Distal joint frame; 115. Screw; 116. Lower joint shaft ; 117. Upper joint shaft; 118. Adapter; 119. Lower rotating shaft; 201. Position sensor; 202. Fingertip connection cable; 203. Intermediate connection cable; 204. Finger root circuit board; 205. Electromechanical interface; 206. Drive connection cable; 207. Magnet; 208. Hall sensor; 209. Fingertip circuit board; 210. Finger root connection cable; 211. Base joint circuit board one; 212. Base joint circuit board two. Detailed Implementation

[0033] The technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings of the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the invention, not all embodiments. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort are within the scope of protection of the present invention.

[0034] like Figures 1-5As shown, a two-degree-of-freedom underactuated robot thumb based on a linear slider mechanism includes a driver 101, a driver 202, a base joint frame 103, a double universal joint 104, a double universal joint 205, a slider 106, a wire lever 107, a wire lever 208, a spring 109, a transmission link 110, a proximal joint frame 111, a pin 112, an upper pivot 113, a distal joint frame 114, a screw 115, a lower joint shaft 116, an upper joint shaft 117, an adapter 118, a lower pivot 119, a position sensor 201, a fingertip connection cable 202, a middle connection cable 203, a finger root circuit board 204, an electromechanical interface 205, a drive connection cable 206, a magnet 207, a Hall sensor 208, a fingertip circuit board 209, a finger root connection cable 210, a base joint circuit board 1 211, and a base joint circuit board 212.

[0035] Combination Figures 1-2 As shown, the mechanical part of the robot thumb of the present invention is illustrated, and its form is as follows:

[0036] The base joint frame 103, the proximal phalanx frame 111, and the distal phalanx frame 114 form the base structure of the thumb. The end of the base joint frame 103 serves as the thumb's fixed position and connects to the palm. The connection between the end of the proximal phalanx frame 111 and the top of the base joint frame 103 forms the metacarpophalangeal joint (MCP). The connection between the end of the distal phalanx frame 114 and the top of the proximal phalanx frame 111 forms the interphalangeal joint (IP). The overall structure adopts a symmetrical arrangement, satisfying the two degrees of freedom of motion of the anthropomorphic thumb: flexion / extension and lateral swing.

[0037] A bearing seat is integrally installed at the rear center of the top of the base joint frame 103 for mounting and supporting the adapter 118. A adapter shaft is provided on the rear side of the adapter 118, arranged horizontally in the front-rear direction. The adapter shaft is rotatably connected to the bearing seat and is axially positioned by the screw 115. A lower joint shaft 116 is provided on the front side of the adapter 118 for connecting the proximal joint frame 111. The lower joint shaft 116 and the adapter shaft of the adapter 118 constitute the rotation axis for the two degrees of freedom of flexion and extension and lateral swing of the MCP joint. The proximal joint frame 111 is a horizontally symmetrical double support rod structure. The bottom end of the proximal joint frame 111 is hinged to both sides of the lower joint shaft 116. The bottom end of the distal joint frame 114 is hinged to the top of the proximal joint frame 111 through an upper joint shaft 117. The upper joint shaft 117 constitutes the rotation axis for the flexion and extension degree of freedom of the IP joint.

[0038] The actuator 101 and actuator 2 102 are symmetrically fixed on both sides of the bottom front of the base joint frame 103, serving as power sources to control the flexion, extension, and lateral swing of the robot's thumb through parallel drive. The output ends of actuator 101 and actuator 2 102 are both arranged upwards and are respectively connected to transmission lever 107 and lever 2 108. The bottom end of lever 107 is connected to the output end of actuator 101 through a double universal joint 104, and the bottom end of lever 2 108 is connected to the output end of actuator 2 102 through a double universal joint 105.

[0039] The transmission link 110 is a Y-shaped structure and is inclinedly positioned at the top between the proximal knuckle frame 111. The ends of the two branch arms of the transmission link 110 are hinged to the front bottom of the distal knuckle frame 114 via the upper rotating shaft 113. The position of the distal knuckle frame 114 is determined by the positions of the upper rotating shaft 113 and the upper joint shaft 117. The main arm of the transmission link 110 is inclined to the rear and has a slide hole through its axial center. The slide rod 106 cooperates with the slide hole to form a sliding pair. The bottom end of the slide rod 106 is hinged to the top of the adapter 118 via the lower rotating shaft 119. The spring 109 is sleeved on the slide rod 106 and elastically supported between the bottom end of the transmission link 110 and the lower rotating shaft 119. A pin 112 is provided at the top of the slide rod 106 to provide axial limit positioning. Meanwhile, two lead screw nuts are integrated side by side on both sides of the bottom end of the main boom of the transmission link 110. The bottom of the two lead screw nuts is inclined forward. The tops of lead lever 107 and lead lever 108 respectively cooperate with the corresponding lead screw nuts to form ball screw pairs, thereby transmitting the power output of the power source to the distal joint frame 114 through the transmission link 110, realizing the bending / extending action of the distal joint frame 114.

[0040] Combination Figures 3-4 The circuitry of the robot thumb of this invention is shown below:

[0041] The position sensor 201 is mounted on the side of the upper joint axis 117 and connected to the fingertip circuit board 209 fixed on the back of the distal phalanx frame 114 via the fingertip connection line 202, for collecting the position signal of the distal phalanx frame 114. The Hall sensor 208 is fixedly mounted at the top center of the base joint frame 103, and the magnet 207 is fixedly mounted at the bottom of the proximal phalanx frame 111 and moves synchronously with it. The magnet 207 and the Hall sensor 208 work together to measure the angles of flexion, extension and lateral movement of the proximal phalanx frame 111. The fingertip circuit board 209 is connected to the Hall sensor 208 via the intermediate connection line 203. To ensure the compactness of the circuit, the intermediate connection line 203 is close to the proximal phalanx frame 111 and passes around the lower joint axis 116 and the lower pivot 119, and is attached to the surface of the adapter 118. After reversing on the surface of the adapter 118, it connects to the Hall sensor 208. The Hall sensor 208 is connected to the finger root circuit board 204 fixed on the top back side of the base joint frame 103 via the finger root connection cable 210, and is used to collect the position signal of the proximal finger joint frame 111.

[0042] The base joint circuit board 1 211 and the base joint circuit board 212 are symmetrically installed on both sides of the bottom of the base joint frame 103, and are respectively connected to the driver 1 101 and the driver 2 102 to control the rotation speed and steering. The base joint circuit board 1 211 and the base joint circuit board 212 are connected in parallel via the drive connection line 206 and then connected to the electromechanical interface 205 fixed on the bottom back side of the base joint frame 103. At the same time, the finger root circuit board 204 is also connected to the electromechanical interface 205. The external control system connected through the electromechanical interface 205 realizes the signal acquisition of the position sensor 201 and the Hall sensor 208, as well as the dynamic control of the driver 1 101 and the driver 2 102.

[0043] Furthermore, to ensure better measurement accuracy, the relative installation positions of magnet 207 and Hall sensor 208 are optimized: In the initial state of the robot's thumb, i.e., when the proximal phalanx frame 111 and distal phalanx frame 114 are in an extended state and no flexion, extension, or lateral movement is performed, the initial positions of magnet 207 and Hall sensor 208 have an angle of 45°, referring to... Figure 4 As shown, when the proximal phalanx frame 111 is simultaneously in the middle position of flexion, extension and lateral swing, the magnet 207 is parallel to the Hall sensor 208. That is, when the position of the magnet 207 is at the zero position of the Hall sensor 208, the movement of the robot thumb of the present invention is in the middle position, thereby reducing the absolute value of the measured angle and making full use of the positive and negative measurement range of the Hall sensor 208 to improve the measurement accuracy.

[0044] Combination Figure 5As shown, the appearance of the robot thumb of the present invention is illustrated. Based on the above-mentioned mechanical and electrical parts, a phalanx shell is installed on the outside of the robot thumb, including a proximal phalanx shell and a distal phalanx shell. The proximal phalanx shell is fixedly sleeved on the outside of the proximal phalanx frame 111 by bolts, and the distal phalanx shell is fixedly sleeved on the outside of the distal phalanx frame 114 by bolts, thus forming a complete robot thumb solution.

[0045] The working principle of this invention is as follows:

[0046] The control system controls the rotation of driver 101 and driver 2102, which in turn drives the rotation of lead lever 107 and lead lever 2108. Since the transmission link 110 is equipped with two lead screw nuts, it can convert the rotational motion of lead lever 107 and lead lever 2108 into the linear motion of the transmission link 110 along the axial direction.

[0047] When the outer shell of the proximal knuckle is not in contact with the object being grasped and is in a state of free rotation:

[0048] Due to the flexible support of the spring 109, the slide bar 106 cannot slide relative to the transmission link 110, while the adapter 118 can deflect left and right relative to the base joint frame 103 around its adapter axis, and the proximal joint frame 111 can rotate back and forth relative to the adapter 118 around the lower joint axis 116. Therefore, the proximal joint frame 111 can generate two degrees of freedom of movement of flexion and extension and lateral swing relative to the base joint frame 103.

[0049] When actuator 101 and actuator 202 rotate in the same direction and at the same speed, lever 107 and lever 208 remain parallel, controlling the axial displacement of transmission link 110 to complete the flexion and extension movements near the phalanx (if both actuator 101 and actuator 202 rotate clockwise, transmission link 110 moves downward axially; conversely, if both actuator 101 and actuator 202 rotate counterclockwise, transmission link 110 moves upward axially, corresponding to the bending and extension movements respectively); when actuator 101 and When the second actuator 102 rotates in the opposite direction at the same speed, the first lever 107 and the second lever 108 will deflect and misalign, causing the proximal phalanx frame 111 to deflect relative to the base joint frame 103 around the adapter shaft of the adapter 118, which in turn drives the proximal phalanx housing to produce a lateral swinging motion around the adapter shaft of the adapter 118 (similarly, if the first actuator 101 rotates clockwise and the second actuator 102 rotates counterclockwise, it corresponds to the outward movement of the lateral swinging motion; conversely, if the first actuator 101 rotates counterclockwise and the second actuator 102 rotates clockwise, it corresponds to the inward movement of the lateral swinging motion).

[0050] When the proximal phalanx shell touches the grasped object, it forces the proximal phalanx shell to stop rotating relative to the base joint frame 103 around the lower joint axis 116:

[0051] Since spring 109 is a flexible support, an adaptive five-bar linkage is formed by slide rod 106, transmission link 110, proximal phalanx frame 111, distal phalanx frame 114, and adapter 118. Slide rod 106 can continue to slide relative to transmission link 110 for a certain distance. Driver 1 101 and driver 2 102 continue to rotate in the same direction and at the same speed. Lever 1 107 and lever 2 108 can continue to control the downward movement of transmission link 110, shortening the upper rotating shaft 113. The distance between the lower rotating shafts 119 drives the distal phalanx frame 114 to bend around the upper joint shaft 117; conversely, when both the driver 101 and the driver 2102 switch to rotating in the opposite direction at the same speed, the lever 107 and the lever 2108 control the transmission link 110 to move upward along the slide bar 106, increasing the distance between the upper rotating shaft 113 and the lower rotating shaft 119, thereby driving the distal phalanx frame 114 to extend around the upper joint shaft 117.

[0052] It will be apparent to those skilled in the art that the present invention is not limited to the details of the exemplary embodiments described above, and that the invention can be implemented in other forms without departing from its spirit or essential characteristics. Therefore, the embodiments should be considered illustrative and non-limiting in all respects, and the scope of the invention is defined by the appended claims rather than the foregoing description. Thus, all variations falling within the meaning and scope of the equivalents of the claims are intended to be included within the present invention. No reference numerals in the claims should be construed as limiting the scope of the claims.

[0053] Furthermore, it should be understood that although this specification describes embodiments, not every embodiment contains only one independent technical solution. This narrative style is merely for clarity. Those skilled in the art should consider the specification as a whole, and the technical solutions in each embodiment can also be appropriately combined to form other embodiments that can be understood by those skilled in the art.

Claims

1. A two-degree-of-freedom underactuated robot thumb based on a linear slide bar mechanism, characterized in that: This includes the base structure, drive mechanism, underactuated linkage mechanism, and measurement mechanism; The base structure includes a base joint frame, a proximal phalanx frame, and a distal phalanx frame. The end of the base joint frame is connected to the palm as a fixed position. The proximal phalanx frame is a transversely symmetrical double support rod structure. The end of the proximal phalanx frame is connected to the top of the base joint frame to form a metacarpophalangeal joint. The end of the distal phalanx frame is connected to the top of the proximal phalanx frame to form an interphalangeal joint. The drive mechanism includes two drivers symmetrically fixed on both sides of the front of the bottom of the base joint frame. The output ends of the two drivers face upward and are respectively connected to the bottom ends of two screw levers through double universal joints. The underactuated linkage mechanism includes a transmission link, a slide bar, and a spring. The transmission link is a Y-shaped structure and is inclinedly positioned at the top between the proximal and distal phalangeal joint frames. The ends of its two branch arms are hinged to the front side of the bottom end of the distal phalangeal joint frame. Its main arm is inclined to the rear and has a through-hole at its axial position. The slide bar cooperates with the slide hole to form a sliding pair. The bottom end of the slide bar is hinged to the metacarpophalangeal joint. The spring is sleeved on the slide bar and elastically supported between the bottom end of the transmission link and the hinge point of the bottom end of the slide bar. Two lead screw nuts are integrated side by side on both sides of the bottom end of the main arm of the transmission link. The bottom of both lead screw nuts is inclined to the front. The top of the two lead screw nuts cooperates with the corresponding lead screw nuts to form a ball screw pair. The measuring mechanism includes a position sensor, a magnet, and a Hall sensor. The position sensor is installed on the side of the interphalangeal joint to collect the position signal of the distal phalanx frame. The magnet is fixed to the bottom of the proximal phalanx frame and moves synchronously with it. The Hall sensor is fixed at the center of the top of the base joint frame. The position signal of the proximal phalanx frame is measured by the cooperation of the magnet and the Hall sensor.

2. The thumb of a two-degree-of-freedom underactuated robot based on a linear slide bar mechanism according to claim 1, characterized in that: A bearing seat is integrally installed at the rear center of the top of the base joint frame for mounting and supporting the adapter. A adapter shaft arranged horizontally along the front-back direction is provided on the rear side of the adapter and is rotatably connected to the bearing seat. The adapter shaft is axially positioned by screws. A lower joint shaft is arranged laterally on the front side of the adapter. The bottom end of the proximal phalanx frame is hinged to both sides of the lower joint shaft. The adapter shaft and the lower joint shaft of the adapter constitute a rotation axis with two degrees of freedom of flexion and extension and lateral swing of the metacarpophalangeal joint.

3. The thumb of a two-degree-of-freedom underactuated robot based on a linear slide bar mechanism according to claim 1, characterized in that: The bottom end of the distal phalanx frame is hinged to the top end of the proximal phalanx frame via an upper joint shaft, and the upper joint shaft constitutes the rotation axis for the flexion and extension degrees of freedom of the interphalangeal joint.

4. The two-degree-of-freedom underactuated robot thumb based on a linear slide bar mechanism according to claim 1, characterized in that: A pin is provided at the top of the slide rod, and the pin provides axial limit positioning for the relative sliding of the slide rod and the transmission connecting rod.

5. The thumb of a two-degree-of-freedom underactuated robot based on a linear slide bar mechanism according to claim 1, characterized in that: In the measuring mechanism, when the proximal phalanx frame is in the middle position of flexion and extension and lateral swing, the magnet is parallel to the Hall sensor, and at this time the magnet is located at the zero position of the Hall sensor.

6. The thumb of a two-degree-of-freedom underactuated robot based on a linear slide bar mechanism according to claim 1, characterized in that: In the measuring mechanism, a position sensor is connected to a fingertip circuit board fixed on the back side of the distal phalanx frame via a connecting wire. The fingertip circuit board is connected to a Hall sensor via a connecting wire. The Hall sensor is connected to a finger root circuit board fixed on the top of the back side of the base joint frame via a connecting wire. The finger root circuit board is connected to an electromechanical interface fixed on the bottom of the back side of the base joint frame. The signal acquisition of the position sensor and the Hall sensor is realized through an external control system connected to the electromechanical interface.

7. A two-degree-of-freedom underactuated robot thumb based on a linear slide bar mechanism according to claim 6, characterized in that: Two base joint circuit boards are symmetrically installed on both sides of the bottom of the base joint frame. The two base joint circuit boards are respectively connected to two drivers to realize the control of speed and direction. The two base joint circuit boards are connected in parallel and connected to the electromechanical interface. The two drivers are dynamically controlled by an external control system through the electromechanical interface.

8. The thumb of a two-degree-of-freedom underactuated robot based on a linear slide bar mechanism according to claim 1, characterized in that: The proximal phalanx frame is fitted with a proximal phalanx shell by bolts, and the distal phalanx frame is fitted with a distal phalanx shell by bolts.

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