A multi-finger cooperative underactuated robot hand

Abstract

The application relates to the technical field of mechanical hands, in particular to a multi-finger cooperative underactuated robot hand. In order to realize flexible control of four fingers by a single motor, the scheme comprises a palm shell, a limiting structure fixed in the palm shell, a transmission assembly and a driving assembly; the transmission assembly comprises a sliding block slidingly connected to the limiting structure and a first spring with one end fixed to the sliding block and the other end serving as a fixed end, and four transmission assemblies are arranged; the driving assembly comprises a first power source fixed to the palm shell, a limiting piece fixed in the palm shell, a first rope, a second rope, a third rope and a fourth rope wound and released by the first power source; the first rope, the second rope, the third rope and the fourth rope are wound on the limiting piece to be higher than all the transmission assemblies, are wound on the four sliding blocks respectively and extend upwards to be connected to fingers, the first spring is used for providing a restoring force to the sliding block connected to the first spring, the first power source is used for pulling the fingers to bend when the first power source is wound, and vice versa to make the fingers stretch.

Description

Technical Field

[0001] This invention relates to the field of robotic arm technology, and more specifically to a multi-finger cooperative underactuated robotic hand. Background Technology

[0002] A robotic arm is an automated device that uses a mechanical structure as its main body and integrates technologies such as drive, control, and sensing to simulate the movements of a human hand or arm, and to perform functions such as grasping, handling, assembling, and manipulating objects. Its core components typically include actuators such as fingers, joints, and arm linkages; drive mechanisms such as motors, cylinders, and hydraulic pumps; servo systems; control mechanisms such as controllers and sensors; human-machine interface units; and support mechanisms such as bases and brackets. Through preset programs or real-time signal commands, it converts energy such as electrical energy, pneumatic energy, and hydraulic energy into precise mechanical motion, replacing or assisting humans in completing specific tasks.

[0003] As an important branch of bionic robotic hands, the rope-driven five-fingered hand uses flexible ropes, such as steel wire ropes and Kevlar ropes, to transmit driving force, thereby driving the movement of multiple joints in the fingers to simulate the bionic structure and dexterity of the human hand. Its existing technology revolves around three core objectives: "driving efficiency, movement precision, and lightweight structure." Specific technical directions and characteristics are as follows:

[0004] From the perspective of drive structure design, existing rope-driven five-finger hands are mainly divided into two categories: centralized drive and distributed drive. Centralized drive solutions often integrate drive motors, such as micro servo motors and stepper motors, into the palm or forearm base. Through transmission components such as pulley systems and guide tubes, one end of the rope is connected to the motor output shaft, and the other end is fixed to the finger joint, usually the distal phalanx. A single rope controls the movement of a single joint or multiple joints in coordination. A typical product is the BionicHand from Festo in Germany. Distributed drive, on the other hand, embeds miniaturized motors directly into the finger joints. The rope only bears the force transmission over short distances, reducing rope length and transmission losses. Micro motors are built into the finger joints, and with the help of 2 to 3 ropes, a single finger joint is controlled, improving the speed of movement response.

[0005] At the control technology level, existing solutions are primarily based on position control and force control. Position control uses encoders to collect motor rotation angles or rope displacement, and combines this with kinematic models to calculate finger joint angles, achieving precise reproduction of preset trajectories. This is often used for grasping regular-shaped objects such as cubes and cylinders, but it is prone to instability when grasping irregular objects due to positional deviations. Force control uses force sensors to detect rope tension or tactile sensors at the fingertips to adjust the motor output torque in real time to control the gripping force. For example, the rope-driven hand driven by the Swiss Maxon motor achieves an adjustable gripping force of 5-50N through rope tension feedback, which can grasp fragile items such as eggs and glass. However, the accuracy of force control is easily affected by rope elastic deformation and pulley friction, and the dynamic response delay is usually 50-100ms. In addition, some high-end products introduce electromyography (EMG) signal control, which analyzes the intention of movement by collecting EMG signals from the human residual limb and drives the rope to adjust the finger posture. However, EMG signals are easily affected by muscle fatigue and environmental interference, and the ability to recognize complex movements is limited.

[0006] In terms of performance and application scenarios, the advantages of existing rope-driven five-fingered hands lie in their lightweight structure and flexible movement. Compared with direct motor drive or hydraulic drive, rope transmission can reduce rigid components at the finger joints. The weight of a single hand is mostly controlled at 400-600g, close to the weight of a human hand of about 500g. The finger bending angle can reach 90°-120°, which can simulate basic actions such as grasping and pinching. It is suitable for prosthetic hands, service robots such as home companion robots, and lightweight industrial assembly such as electronic component assembly.

[0007] However, rope-driven five-finger hands also have shortcomings. Because they mostly use rigid joints connected in series or simple underactuated designs, they struggle to dynamically adjust contact posture and envelope based on object shape. Furthermore, the fixed joint movement trajectories of traditional finger structures cannot simulate the flexible grasping characteristics of the human hand, which "deforms with the object." This limits their adaptability to complex shapes in unstructured environments, making it difficult to meet diverse grasping needs. On the other hand, existing rope-driven five-finger hands generally employ a "multi-motor-to-multi-finger" drive scheme to ensure the independence of each finger's movement. This means each finger or joint is equipped with an independent drive motor, resulting in a complex internal hand structure, large space occupation, and increased overall device weight and energy consumption. While some underactuated designs attempt to reduce the number of motors, they mostly achieve multi-finger linkage through rigid rope coupling, failing to achieve the efficient control of "precise single-motor driving multiple fingers."

[0008] To achieve multi-degree-of-freedom movement and precise control, existing rope-driven five-finger prostheses require multiple sets of high-precision micro servo motors, dedicated planetary gearboxes, high-sensitivity tension sensors, and complex controllers. These core components largely rely on imports or custom production, resulting in high procurement costs. Furthermore, the complex rope drive layout and assembly process demand stringent production precision, requiring specialized debugging equipment and professional technicians, further increasing manufacturing costs. In addition, the specialized operational requirements for after-sales maintenance, such as rope replacement, pre-tension calibration, and motor repair, also increase long-term operating costs for users, leading to persistently high prices and hindering widespread adoption in civilian prosthetics and general industrial assistive devices. Summary of the Invention

[0009] This invention provides a multi-finger cooperative underactuated robotic hand, the purpose of which is to enable flexible control of four fingers to bend the palm using a single motor.

[0010] The above objectives are achieved through the following technical solutions:

[0011] A cooperative underactuated robot hand includes: a hand shell, a limiting structure fixed inside the hand shell, a transmission component, and a drive component;

[0012] The transmission assembly includes a slider that is slidably connected to the limiting structure, and a first spring that is fixed at one end to the slider and at the other end as a fixed end. The transmission assembly is provided with four springs.

[0013] The drive assembly includes a first power source fixed to the palm shell, a limiting member fixed inside the palm shell, and a first rope, a second rope, a third rope, and a fourth rope that are wound and released by the first power source.

[0014] The first, second, third, and fourth ropes are wound around the limiting member above all the transmission components and are respectively wound around the four sliders and extend upward to connect the fingers. The first spring is used to provide a force to reset the slider connected to it. When the first power source is wound, it is used to pull the finger to bend. When the first power source is released, it is used to extend the finger.

[0015] The four transmission components are arranged from left to right to correspond to the index finger, middle finger, ring finger and little finger respectively. The heights of the four sliders are arranged from high to low as the second slider from the left, the first slider from the left, the third slider from the left and the fourth slider from the left.

[0016] The other end of the first spring of the transmission component located on the right end faces downward, while the other end of the first spring of the other transmission components faces upward. The first springs corresponding to the little finger and middle finger are tension springs, and the first springs corresponding to the ring finger and index finger are compression springs.

[0017] The first rope's driving end moves downwards towards the right side of the slider corresponding to the little finger, then clockwise around to the left and finally extends upwards; the second rope's driving end moves from right to left and downwards, passing over the slider corresponding to the little finger, then clockwise around the bottom right side of the slider corresponding to the ring finger to the left, and finally extends upwards; the third rope's driving end moves from right to left and downwards, passing over the slider corresponding to the little finger, then clockwise around the bottom right side of the slider corresponding to the ring finger to the left, then tilts upwards to the left, clockwise around the bottom of the slider corresponding to the middle finger to the left, and finally extends upwards; the fourth rope's driving end moves downwards, passing over the slider corresponding to the little finger, then clockwise around the bottom right side of the slider corresponding to the ring finger to the left, then tilts upwards to the left, counterclockwise around the top right side of the slider corresponding to the middle finger to the left, then tilts downwards to the left, clockwise around the bottom right side of the slider corresponding to the index finger to the left, and finally extends upwards.

[0018] Alternatively, the first spring corresponding to the little finger and ring finger is a tension spring, and the first spring corresponding to the middle finger and index finger is a compression spring;

[0019] The first rope's driving end moves downwards towards the right side of the slider corresponding to the little finger, then clockwise around to the bottom right side until it reaches the left side, and finally extends upwards. The second rope, in the same manner as the first rope, wraps around the slider corresponding to the little finger, then tilts to the upper left, clockwise around from the bottom of the slider corresponding to the ring finger to the left side, and finally extends upwards. The third rope, in the same manner as the first rope, wraps around the slider corresponding to the little finger, then tilts to the upper left, counterclockwise around from the top right side of the slider corresponding to the ring finger to the left side, then tilts to the lower left, clockwise around from the bottom right side of the slider corresponding to the middle finger to the left side, and finally extends upwards. The fourth rope, in the same manner as the third rope, wraps around the sliders corresponding to the little and ring fingers, passes under the slider corresponding to the middle finger, clockwise around from the bottom right side of the slider corresponding to the index finger to the left side, and finally extends upwards.

[0020] The limiting structure includes a boss fixed on the palm shell and a cylindrical rod fixed on the boss; the slider includes a base and guide wheels rotatably connected to the base, so that any one base can be inserted into at least two cylindrical rods, and the four guide wheels are in contact with the first rope, the second rope, the third rope and the fourth rope respectively, and the contact is a rolling friction.

[0021] A finger assembly for use with the aforementioned collaborative underactuated robot hand includes a base, a first phalanx located above the base, a first connector rotatably connected to the base, a first torsion spring fitted on the first connector, a first wheel rotatably connected to the first connector, and a second phalanx disposed above the first phalanx. The first phalanx is rotatably connected to the first connector, and the first torsion spring provides a force for the first phalanx to extend relative to the base.

[0022] It also includes a second phalanx located above the first phalanx, a second connector rotatably connected to the upper side of the first phalanx, a second torsion spring fitted on the second connector, a second wheel rotatably connected to the second connector, the second phalanx being rotatably connected to the second connector, and the second torsion spring providing a force for the second phalanx to extend relative to the first phalanx;

[0023] It also includes a third phalanx positioned above the second phalanx, a third connector rotatably connected to the upper side of the second phalanx, a third torsion spring fitted onto the third connector, the third phalanx being rotatably connected to the third connector, and the third torsion spring providing a force for the third phalanx to extend relative to the second phalanx.

[0024] The base is fixed to the palm shell, and the first rope, second rope, third rope or fourth rope can be wrapped around the first wheel and second wheel at least once from bottom to top, and fixed on the third finger joint.

[0025] It also includes a third wheel, which is rotatably connected to the third connector or fixed to the third knuckle. The third wheel supports the first rope, the second rope, the third rope, or the fourth rope to extend in a forward direction away from the rotation center of the third knuckle.

[0026] It also includes a compensation mechanism, which includes a transmission base, a first connecting rod slidably connected to the transmission base, a second connecting rod fixed to the transmission base, one end of a second spring fixed to the transmission base, and the other end of the second spring fixed to the output shaft of a second power source, the second power source being fixedly connected to the first connecting rod; the bottom of the first connecting rod is rotatably connected to a base or a first finger joint; when the bottom of the first connecting rod is rotatably connected to the base, the top of the second connecting rod is rotatably connected to the second finger joint; when the bottom of the first connecting rod is rotatably connected to the first finger joint, the top of the second connecting rod is rotatably connected to the third finger joint.

[0027] There are notches formed between the first phalanx and the base, between the second phalanx and the base, and between the third phalanx and the second phalanx, on the side closer to the bending direction, and the sides opposite to the bending direction can lock into each other.

[0028] A multi-finger cooperative underactuated robotic hand includes a cooperative underactuated robotic hand and four finger assemblies. The positions of the four finger assemblies correspond to the positions of a first rope, a second rope, a third rope, and a fourth rope in the longitudinal direction, respectively. The first rope, the second rope, the third rope, and the fourth rope are respectively inserted into the four adjacent finger assemblies.

[0029] The beneficial effects of this invention's multi-finger cooperative underactuated robotic hand are as follows:

[0030] The drive system is significantly simplified while maintaining finger dexterity. This invention achieves coordinated drive of four fingers by a single motor. Compared to the traditional "multiple motors for multiple fingers / joints" approach, the number of motors, internal mounting brackets, and wiring harnesses are greatly reduced, significantly lowering the complexity of the transmission structure. The overall device is more compact and significantly lighter, making it more suitable for size- and weight-sensitive scenarios such as prosthetic wear and portable operation. Long-term use can reduce muscle burden on users. Unlike the rigid coupling of existing underactuated designs, the transmission matching structure of this invention optimizes the connection method and tension distribution between the rope and finger joints, ensuring that the four fingers can independently complete bending and extension movements of different amplitudes. When grasping, it can naturally simulate the basic hand movement logic, simplifying the drive system while ensuring the flexibility and controllability of each finger's movement.

[0031] The invention significantly improves the independence of multi-finger movements, enhancing the fault tolerance and overall stability of the grasping process. By incorporating springs into the rope wiring scheme, when a single finger stops moving due to contact with an object or external force during grasping, the spring can quickly absorb the sudden change in rope tension corresponding to that finger. This prevents tension fluctuations from interfering with other fingers through a shared transmission path, completely eliminating the problem of "single-finger movement causing multi-finger movement jamming and posture deviation" in existing solutions. This ensures that the remaining fingers can continue to complete the enveloping and grasping actions normally. This improved independence allows the device to adopt a flexible strategy of "some fingers contacting and positioning first, and the remaining fingers following up with enveloping" when grasping irregularly shaped objects. It does not require the synchronous movement of all fingers. Even if the object's placement is off, stable grasping can be achieved through independent adjustment of the fingers, greatly improving the fault tolerance and overall stability of grasping in unstructured scenarios.

[0032] The shape-adaptive performance is significantly improved, achieving an organic combination of passive adaptation and active fine-tuning. This invention employs a series composite design of linkages, springs, and micro-motors / cylinders. When dealing with irregularly shaped, non-standard objects with significant size differences, the linkage first achieves initial contact with the object's surface via rope drive. Subsequently, under the combined influence of rope tension and surface contact force, the linkage moves along a fixed guide rail, dynamically adapting the finger shape to the object's contour, achieving a tight envelope, increasing the contact area, balancing force, and preventing grip failure. Simultaneously, the built-in micro-motor dynamically adjusts the spring preload, deformation amplitude, and return rhythm according to the object's material and weight, thereby fine-tuning the linkage position and joint angle to achieve complete adaptation to the object's shape. This active compensation function also mitigates fatigue decay that may occur with long-term spring use, maintaining stable adaptive performance, extending service life, and significantly broadening the adaptability range for diverse gripping scenarios.

[0033] The dual-scheme linkage generates synergistic advantages, further enhancing resistance to external forces and gripping stability. The linkage design of the "spring-micro motor / electric cylinder composite adaptive finger" and the "pulley-slider-spring winding system" in this invention produces a synergistic effect that a single solution cannot achieve. When gripping complex and irregular objects, the composite adaptive finger first completes precise contour fitting and initial clamping, while the spring winding system achieves the coordinated transmission and storage of force from all four fingers. When subjected to slight external pulling, the adaptive finger can continue to conform to the object's contour due to its flexibility, while the force stored in the spring system is quickly released, causing the four fingers to tighten collaboratively, firmly locking the object. Stable gripping can be maintained without additional complex motor control, significantly improving the reliability and practicality of the device in dynamic environments. Attached Figure Description

[0034] Figure 1 This is a schematic diagram of the structure of a multi-finger cooperative underactuated robot hand according to the present invention;

[0035] Figure 2 A schematic diagram of the rear part of the palm shell 1 of a multi-finger collaborative underactuated robot hand after removal;

[0036] Figure 3 for Figure 2 An enlarged schematic diagram of point A in the middle;

[0037] Figure 4 A gesture indicating the fingers Figure 1 ;

[0038] Figure 5 A gesture indicating the fingers Figure 2 ;

[0039] Figure 6 A schematic diagram of the internal structure of a finger;

[0040] Figure 7 This is a schematic diagram of the base structure;

[0041] Figure 8 This is a schematic diagram of the structure of the first phalanx;

[0042] Figure 9 This is a schematic diagram of the structure of the second phalanx;

[0043] Figure 10 This is a schematic diagram of the structure of the third phalanx;

[0044] Figure 11 This is a schematic diagram of the compensation mechanism.

[0045] In the diagram: 1. Hand shell; 1-1. Limiting structure; 2. Base; 2-1. Guide wheel; 2-2. First spring; 3. Limiting wheel; 4. First power source; 4-1. First rope; 4-2. Second rope; 4-3. Third rope; 4-4. Fourth rope; 5. Base; 6. First knuckle; 7. First connector; 7-1. First torsion spring; 7-2. First wheel; 8. Second knuckle; 9. Second connector; 9-1. Second torsion spring; 9-2. Second wheel; 10. Third knuckle; 11. Third connector; 11-1. Third torsion spring; 11-2. Third wheel; 12. Transmission seat; 12-1. First connecting rod; 12-2. Second connecting rod; 12-3. Second power source; 12-4. Second spring. Detailed Implementation

[0046] A multi-finger cooperative underactuated robotic hand, such as Figures 1 to 2 As shown, the robot includes a cooperative underactuated robot hand and finger assembly. The cooperative underactuated robot hand includes a hand shell 1, a limiting structure 1-1 disposed on the hand shell 1, a transmission assembly, and a drive assembly.

[0047] like Figure 3 As shown, the transmission assembly includes a base 2, a guide wheel 2-1 rotatably connected to the base 2 via a bearing, and a first spring 2-2 fixed at one end to the base 2. The guide wheel 2-1 has a flange that prevents the rope from detaching from itself. The transmission assembly consists of four parts, with all four bases 2 slidably connected to the limiting structure 1-1, allowing only longitudinal freedom for longitudinal sliding. The base 2 and guide wheel 2-1 combine to form a slider for rolling friction with the rope.

[0048] In this design, considering weight reduction, the limiting structure 1-1 is a guide groove on the palm shell 1, and a wedge-shaped / T-shaped key is fixed on the base 2, with the key slidably connected within the guide groove. Preferably, the limiting structure 1-1 includes a protrusion fixed on the palm shell 1 and a cylindrical rod fixed on the protrusion. The base 2 has a hole that mates with the cylindrical rod, allowing any one base 2 to be inserted into at least two cylindrical rods for a sliding connection, and the cylindrical rods are not shared between bases 2. Figure 2 and 3 The example provided is an example of using three cylindrical rods exclusively for any one of the bases 2, which are referred to as guides below.

[0049] The palm shell 1 is made of ABS engineering plastic in one piece, with a size of approximately 100mm×90mm×25mm; the first spring 2-2 has a stiffness coefficient of 2N / mm, and the length of each spring can be different depending on the position arrangement.

[0050] In one embodiment, the four transmission components are arranged sequentially from left to right. For ease of description, Figures 1 to 3For the right hand, four transmission components are used to transmit the index, middle, ring, and little fingers respectively. The other end of the first spring 2-2 of the transmission component located on the right side faces downward and is fixed to the limiting structure 1-1 or the palm shell 1, while the other ends of the first spring 2-2 of the other transmission components face upward and are fixed to the limiting structure 1-1 or the palm shell 1.

[0051] The drive assembly includes a first power source 4, a first rope 4-1, a second rope 4-2, a third rope 4-3, and a fourth rope 4-4 fixed inside the palm shell 1. The first power source 4 uses a micro servo motor with an output torque greater than 10 kg·cm. The output shaft of the first power source 4 is positioned downwards and located in the lower left area of ​​the palm shell 1. One end of each of the four ropes (first rope 4-1, second rope 4-2, third rope 4-3, and fourth rope 4-4) is sequentially fixed to the output shaft of the first power source 4 from front to back, thereby using the rotation of the output shaft of the first power source 4 to wind or unwind the four ropes. The first rope 4-1, second rope 4-2, third rope 4-3, and fourth rope 4-4 are used to drive the little finger, ring finger, middle finger, and index finger, respectively.

[0052] The drive assembly also includes a limiting wheel 3 rotatably connected to the palm shell 1, located to the upper right of all the guide wheels 2-1. The position of the limiting wheel 3 allows the first rope 4-1, the second rope 4-2, the third rope 4-3, and the fourth rope 4-4 to rotate counterclockwise from the lower right of the limiting wheel 3 to the upper part of the limiting wheel 3 and then to the left side. Furthermore:

[0053] The other end of the first rope 4-1 is lowered close to the right side of the guide wheel 2-1 of the transmission component used to drive the little finger, then clockwise around to the bottom right side of the guide wheel 2-1 of the transmission component until the left side, and finally upward to connect with the end of the proximal phalanx of the little finger to drive the movement of the little finger.

[0054] The other end of the second rope 4-2 passes from right to left and downwards over the transmission component used to drive the little finger, then clockwise from the bottom right side of the guide wheel 2-1 of the transmission component that drives the ring finger to the left side, and finally connects upwards to the end of the proximal phalanx of the ring finger to drive the movement of the ring finger.

[0055] The other end of the third rope 4-3 slopes downward from right to left, passing over the transmission component used to drive the little finger, clockwise around the bottom right side of the guide wheel 2-1 of the transmission component driving the ring finger to the left side, then slopes upward to the left, counterclockwise around the bottom of the guide wheel 2-1 of the transmission component driving the middle finger to the left side, and finally connects upward to the end of the proximal phalanx of the middle finger to drive the movement of the middle finger.

[0056] The other end of the fourth rope 4-4 slopes downwards from right to left, passing over the transmission assembly that drives the little finger. Then, clockwise, it wraps around the bottom right side of the guide wheel 2-1 of the transmission assembly that drives the ring finger to the left side, then slopes upwards to the left. Counterclockwise, it wraps around the top right side of the guide wheel 2-1 of the transmission assembly that drives the middle finger to the left side, then slopes downwards to the left. Clockwise, it wraps around the bottom right side of the guide wheel 2-1 of the transmission assembly that drives the index finger to the left side, finally connecting upwards to the end of the proximal phalanx of the index finger to drive its movement. The other end of each of these ropes is the driving end that drives the finger.

[0057] In the initial state, all fingers are not bent and are in a natural state. The first rope 4-1, the second rope 4-2, the third rope 4-3, and the fourth rope 4-4 are in a taut state. In this state:

[0058] In the transmission assembly that drives the little finger: the first spring 2-2 is a tension spring, the lower end of the first spring 2-2 is fixed on the boss, the upper end of the first spring 2-2 is fixed on the lower end of the base 2, and the first spring 2-2 gives the base 2 a downward pulling force.

[0059] In the transmission assembly that drives the ring finger: the first spring 2-2 is a compression spring. The upper end of the first spring 2-2 is fixed to the upper wall inside the palm shell 1, and the lower end of the first spring 2-2 is fixed to the upper end of the base 2. The first spring 2-2 gives the base 2 a downward pushing force.

[0060] In the transmission assembly that drives the middle finger: the first spring 2-2 is a tension spring. The upper end of the first spring 2-2 is fixed to the upper wall inside the palm shell 1, and the lower end of the first spring 2-2 is fixed to the upper end of the base 2. The first spring 2-2 gives the base 2 an upward pulling force.

[0061] In the transmission assembly that drives the index finger: the first spring 2-2 is a compression spring. The upper end of the first spring 2-2 is fixed to the upper wall inside the palm shell 1, and the lower end of the first spring 2-2 is fixed to the upper end of the base 2. The first spring 2-2 gives the base 2 a downward pushing force.

[0062] When the robotic arm needs to grasp, the first power source 4 rotates forward to wind up the rope, pulling the four fingers to bend simultaneously. If a finger touches the object first and stops, the corresponding first spring 2-2 makes an adaptive adjustment, extending or contracting, while the other fingers continue to bend and envelop the object. Specifically:

[0063] The first rope 4-1 contracts, causing the guide wheel 2-1 and the first spring 2-2 in the transmission assembly of the little finger to move slightly along the guide rail toward the little finger or remain stationary. The first rope 4-1 pulls the end of the proximal phalanx of the little finger toward the palm of the hand shell 1.

[0064] The second rope 4-2 contracts, causing the guide wheel 2-1 and the first spring 2-2 in the transmission assembly of the ring finger to move slightly along the guide rail toward the ring finger or remain stationary. The second rope 4-2 pulls the end of the proximal phalanx of the ring finger toward the palm of the hand shell 1.

[0065] When the third rope 4-3 contracts, the guide wheel 2-1 and the first spring 2-2 in the transmission assembly that drives the middle finger are affected by the combined action of the third rope 4-3 and the fourth rope 4-4, and move slightly away from the middle finger along the guide rail or remain stationary. The third rope 4-3 pulls the end of the proximal phalanx of the middle finger to bend towards the palm of the hand shell 1.

[0066] The fourth rope 4-4 contracts, causing the guide wheel 2-1 and the first spring 2-2 in the transmission assembly of the index finger to move slightly along the guide rail toward the index finger or remain stationary. The third rope 4-4 pulls the end of the proximal phalanx of the index finger toward the palm of the hand shell 1.

[0067] When a finger can no longer bend after gripping an object due to bending, the corresponding spring adapts by extending or contracting, causing the corresponding base 2 to move longitudinally, thus generating the degree of freedom required for the rope to wind up. Specifically:

[0068] When the little finger can no longer bend after grasping the object due to bending, the first rope 4-1 continues to wind up, the guide wheel 2-1 in the transmission component that drives the little finger continues to move upward, and the corresponding first spring 2-2 continues to stretch to compensate.

[0069] When the ring finger can no longer bend after gripping an object due to bending, the guide wheel 2-1 in the transmission component that drives the ring finger continues to move upward as the second rope 4-2 continues to wind up, and the corresponding first spring 2-2 further contracts to compensate.

[0070] When the middle finger can no longer bend after gripping an object due to bending, both the third rope 4-3 and the fourth rope 4-4 continue to wind up. Since the angle between the direction of the force of the fourth rope 4-4 on the adjacent guide wheel 2-1 and the direction of the guide rail is smaller than the angle between the direction of the force of the third rope 4-3 on the adjacent guide wheel and the direction of the guide rail, the component force along the guide rail provided by the fourth rope is greater than the component force along the guide rail provided by the third rope. The guide wheel 2-1 in the transmission component of the middle finger moves downward, and the corresponding first spring 2-2 continues to stretch to compensate. In addition, the continued winding of the third rope will also cause the transmission component of the ring finger to continue to move upward, and the corresponding first spring 2-2 further contracts to compensate.

[0071] When the index finger can no longer bend after gripping an object due to bending, the fourth rope 4-4 continues to wind up, causing the guide wheel 2-1 in the transmission component driving the middle finger to continue moving upwards. The corresponding first spring 2-2 further contracts to compensate. The continued winding of the fourth rope 4-4 also causes the guide wheels 2-1 in the transmission components of the middle finger and ring finger to experience downward and upward forces respectively, with the first spring 2-2 in their respective transmission components providing compensation.

[0072] Conversely, the release command triggers the motor to reverse, the ropes slacken, and each finger extends under the reset action of the first springs 2-2. All the aforementioned ropes are made of steel wire rope.

[0073] To optimize the layout, a second limiting wheel 3 can be fixed inside the palm shell 1 on the right side, so that the four ropes approach the limiting wheel 3 from left to right, and then wind counterclockwise from the bottom of the second limiting wheel 3 upwards towards the first limiting wheel 3, and then wind counterclockwise from the right side of the first limiting wheel 3 to it.

[0074] Example 2: The position of the limiting wheel 3 remains unchanged, so that the first rope 4-1, the second rope 4-2, the third rope 4-3 and the fourth rope 4-4 can still be wound counterclockwise from the lower right of the limiting wheel 3 to the upper part of the limiting wheel 3 and then to the left side.

[0075] The other end of the first rope 4-1 is lowered close to the right side of the guide wheel 2-1 of the transmission component used to drive the little finger, and then clockwise around to the bottom right side of the guide wheel 2-1 of the transmission component until the left side, and finally upward to connect with the end of the proximal phalanx of the little finger to drive the movement of the little finger; unlike the previous scheme, the spring is changed to a tension spring and fixed on the upper wall inside the palm shell.

[0076] The second rope 4-2 passes around the guide wheel of the transmission component driving the little finger in a manner similar to that of the first rope 4-1, then tilts upwards and to the left, clockwise around the bottom of the guide wheel 2-1 of the transmission component driving the ring finger to the left side, and finally connects upwards to the end of the proximal phalanx of the ring finger to drive the movement of the ring finger. This is basically the same as the way the third rope 4-3 passes around the guide wheel of the middle finger component in the original scheme. The difference from the previous scheme is that the spring of the ring finger component is changed to a tension spring.

[0077] The third rope 4-3 passes around the guide wheel of the transmission component driving the little finger in approximately the same manner as the first rope 4-1, then tilts upwards to the left, counterclockwise from the top right side of the guide wheel 2-1 of the transmission component driving the ring finger to the left side, then tilts downwards to the left, clockwise from the bottom right side of the guide wheel 2-1 of the transmission component driving the middle finger to the left side, and finally connects upwards to the end of the proximal phalanx of the middle finger to drive the movement of the middle finger. Unlike the previous scheme, the spring in the middle finger component is now a compression spring.

[0078] The fourth rope 4-4 wraps around the little finger, and the ring finger drive component is basically the same as the third rope 4-3 in this scheme. This rope does not wrap around the drive component of the middle finger or only passes by the bottom, and goes clockwise from the bottom right side of the guide wheel 2-1 of the transmission component that drives the index finger to the left side, and finally connects upward to the end of the proximal phalanx of the index finger to drive the movement of the index finger.

[0079] Example 1 of using fingers:

[0080] like Figures 5 to 10 The finger assembly shown includes a base 5 and a first phalanx 6 located above the base 5 and rotatable relative to the base 5. Specifically, a first connector 7 is rotatably connected to the base 5, and a first torsion spring 7-1 is fitted onto the first connector 7. The first torsion spring 7-1 provides a force for the first phalanx 6 to rotate clockwise, causing the first phalanx 6 to engage with the upper part of the base 5, maintaining their relative extended state. A first wheel 7-2 is rotatably connected to the first connector 7. Thus, the first connector 7 connects the base 5, the first phalanx 6, and the first wheel 7-2, all of which can rotate relative to the first connector 7.

[0081] Continuing the explanation, a second phalanx 8, capable of rotating relative to itself, is also provided above the first phalanx 6. Similarly, a second connecting member 9 is rotatably connected to the upper side of the first phalanx 6. A second torsion spring 9-1 is fitted onto the second connecting member 9, providing a force for the second phalanx 8 to rotate clockwise, causing the second phalanx 8 to engage with the upper part of the first phalanx 6, maintaining their relative extended state. A second wheel 9-2 is rotatably connected to the second connecting member 9. Thus, the second connecting member 9 connects the first phalanx 6, the second phalanx 8, and the second wheel 9-2, all of which can rotate relative to the second connecting member 9.

[0082] Continuing the explanation, a third phalanx 10, capable of rotating relative to itself, is positioned above the second phalanx 8. Similarly, a third connector 11 is rotatably connected to the upper side of the second phalanx 8. A third torsion spring 11-1 is fitted onto the third connector 11, providing a clockwise rotational force to the third phalanx 10, causing it to engage with the upper part of the second phalanx 8 and maintain their relative extended state. A third wheel 11-2 is rotatably connected to the third connector 11, or the third wheel 11-2 is fixed to the third phalanx 10. The third connector 11 connects the second phalanx 8, the third phalanx 10, and the third wheel 11-2, all of which can rotate relative to the third connector 11.

[0083] There are four finger components: index finger, middle finger, ring finger, and little finger. Each finger component corresponds one-to-one with one of the four transmission components, and the connection scheme between each pair of finger components and transmission components is the same, for example:

[0084] The first rope 4-1 is used to drive the little finger. Within the little finger: the first rope 4-1 extends from bottom to top to the front of the first wheel 7-2, maintaining contact with the first wheel 7-2, and then clockwise around the top, back, bottom, and front of the first wheel 7-2, completing a full rotation. It continues upwards to the front of the second wheel 9-2 and completes a full rotation in the same manner. Finally, the first rope 4-1 continues upwards to the front of the third wheel 11-2 and is fixed in the third phalanx 10. The base 5 is fixed to the upper end of the palm shell 1. Regarding the mentioned full rotation, the number of rotations of the rope and wheel is not limited; it can also complete two full rotations.

[0085] Similarly, the connection schemes for the second rope 4-2 to the ring finger, the third rope 4-3 to the middle finger, and the fourth rope 4-4 to the index finger are the same as those described above.

[0086] Finger contraction and repositioning principle: For ease of description, the first rope 4-1, the second rope 4-2, the third rope 4-3, and the fourth rope 4-4; the first phalanx 6, the second phalanx 8, and the third phalanx 10 are simply referred to as each phalanx. The first torsion spring 7-1, the second torsion spring 9-1, and the third torsion spring 11-1 are simply referred to as each torsion spring. The first wheel 7-2, the second wheel 9-2, and the third wheel 11-2 are simply referred to as each wheel.

[0087] Because the downward pull provided by the first rope 4-1 during winding is located in front of the rotation center of each finger joint, and a gap is formed between the front sides of any two adjacent finger joints, and also between the front sides of the first finger joint 6 and the base 5, each finger joint has the freedom to bend forward and downward. When the first power source 4 rotates clockwise to wind the first rope 4-1, the contraction of the first rope 4-1 pulls the third finger joint 10 forward and downward, thereby causing each finger joint to rotate counterclockwise, thus achieving finger bending. At this time, relative sliding occurs between the first rope 4-1 and each wheel, increasing the elastic potential energy of each torsion spring. When the first power source 4 releases the ropes, the torsion springs cause each finger joint to rotate clockwise to reset, thus achieving finger extension.

[0088] Further explanation, such as Figure 11 As shown, the finger assembly also includes a compensation mechanism, which includes: a transmission base 12, with a first connecting rod 12-1 inserted into itself below the transmission base 12, the first connecting rod 12-1 sliding only longitudinally relative to the transmission base 12. A second connecting rod 12-2 fixed to itself is disposed above the transmission base 12. One end of a second spring 12-4 is fixed to the transmission base 12, and the output shaft of a second power source 12-3 is fixed to the other end, i.e., the top, of the second spring 12-4. The second power source 12-3 is fixedly connected to the first connecting rod 12-1.

[0089] Each finger assembly contains two compensation mechanisms, arranged one above the other. In the lower compensation mechanism: the bottom of the first link 12-1 is rotatably connected to the base 5, and the top of the second link 12-2 is rotatably connected to the second phalanx 8. Similarly, in the upper compensation mechanism: the bottom of the first link 12-1 is rotatably connected to the first phalanx 6, and the top of the second link 12-2 is rotatably connected to the third phalanx 10.

[0090] Since there is almost no relative movement between the first link 12-1 and the second link 12-2 when the finger is not in contact with an object and the second power source 12-3 is not adjusted, they can be considered as a fixed-length whole, and the finger is a system with only one degree of freedom. When the first rope 4-1 contracts, the third phalanx 10 is first subjected to a bending force, which is transmitted from the two segments considered as a fixed-length whole to the second phalanx 8 and the first phalanx 6, causing each phalanx to bend, thereby achieving coupled motion. When the first rope 4-1 returns to its original position, the first phalanx 6, the second phalanx 8, and the third phalanx 10 return to their original position using the first torsion spring 7-1, the second torsion spring 9-1, and the third torsion spring 11-1.

[0091] The transmission principle of the compensation mechanism is as follows: Before contact with the object, the first rope 4-1 drives the little finger to perform normal coupling motion. After contact with the object, the little finger completes the initial envelopment of the object through coupling motion. Under the combined action of the tension of the first rope 4-1 and the contact force of the object on each finger joint, the second link 12-2 begins to slide relative to the first link 12-1, and finally comes to rest under the balance of the force of the second spring 12-4, completing the self-adaptation to the shape of the object. If there are requirements for the preload of the second spring 12-4, the speed of the link movement, or if it is believed that the finger has not fully adapted to the shape of the object, the deformation degree of the second spring 12-4 can be adjusted by the second power source 12-3 to fine-tune the position of the first link 12-1 and the second link 12-2 to change the corresponding finger joint angle, thus achieving complete adaptation to the shape of the object.

[0092] For example, in the compensation mechanism located above: the second spring 12-4 is a tension spring, and the second power source 12-3 is a linear motor, such as an electric push rod. When the second power source 12-3 extends, it pushes the transmission seat 12 downwards, causing the second spring 12-4 to extend and its tension to increase. This, in turn, causes the second connecting rod 12-2 to move downwards along the first connecting rod 12-1, and the first connecting rod 12-1 also moves upwards. This means that the overlapping portion of the two connecting rods increases, and the total length of the two connecting rods shortens. Therefore, not only does the second connecting rod 12-2 cause the third finger joint 10 to rotate counterclockwise relative to the second finger joint 8, reducing the angle between them; it also causes the first connecting rod 12-1 to cause the second finger joint 8 to rotate counterclockwise relative to the first finger joint 6, reducing the angle between them.

[0093] Similarly, as the second power source 12-3 shortens, the second spring 12-4 contracts, the transmission seat 12 returns to its original position, and the tension of the second spring 12-4 decreases, causing the second connecting rod 12-2 to move upward along the first connecting rod 12-1. The first connecting rod 12-1 moves upward, reducing the overlap between the two connecting rods and increasing their total length. Therefore, it is possible that not only does the second connecting rod 12-2 cause the third finger joint 10 to rotate clockwise relative to the second finger joint 8, increasing their angle, but the first connecting rod 12-1 also causes the second finger joint 8 to rotate clockwise relative to the first finger joint 6, increasing their angle as well.

[0094] Similarly, in the compensation mechanism located below:

[0095] The extension of the second power source 12-3 pushes the transmission seat 12 downward, causing the second spring 12-4 to extend and its tension to increase. This increases the downward movement of the second connecting rod 12-2 along the first connecting rod 12-1, while the first connecting rod 12-1 also moves upward. This results in an increased overlap between the two connecting rods and a shortening of their total length. Therefore, it is possible that not only does the second connecting rod 12-2 cause the second finger joint 8 to rotate counterclockwise relative to the first finger joint 6, reducing their included angle, but the first connecting rod 12-1 also causes the first finger joint 6 to rotate counterclockwise relative to the base 5, further reducing their included angle.

[0096] Similarly, as the second power source 12-3 shortens, the second spring 12-4 contracts, the transmission seat 12 returns to its original position, and the tension of the second spring 12-4 decreases, causing the second connecting rod 12-2 to move upward along the first connecting rod 12-1. The first connecting rod 12-1 moves upward, reducing the overlap between the two connecting rods and increasing their total length. Therefore, it is possible that not only does the second connecting rod 12-2 cause the second finger joint 8 to rotate clockwise relative to the first finger joint 6, increasing their angle, but the first connecting rod 12-1 also causes the first finger joint 6 to rotate clockwise relative to the base 5, increasing their angle as well.

[0097] In addition to driving the aforementioned fingers, the transmission component of this invention can also drive other similar multi-segmented fingers.

[0098] It should be noted that while preferred embodiments of this application are provided in the specification and accompanying drawings, this application can be implemented in many different forms and is not limited to the embodiments described herein. These embodiments are not intended to impose additional limitations on the content of this application; their purpose is to provide a more thorough and comprehensive understanding of the disclosure of this application. Furthermore, the above-described technical features can be combined with each other to form various embodiments not listed above, all of which are considered to be within the scope of this specification. Moreover, those skilled in the art can make improvements or modifications based on the above description, and all such improvements and modifications should fall within the protection scope of the appended claims.

[0099] For example, adding control over the thumb or adjusting other movement directions of the fingers using stacked motors, based on the above, does not deviate from the scope of protection of this application. (See reference:)

[0100] The paper, titled "Development of a Multisensory Underactuated Prosthetic Hand with Fully Integrated Electronics," was published in IEEE / ASME TRANSACTIONSON MECHATRONICS. In this paper, the thumb structure is driven by a two-motor linkage. Even if the other four fingers adopt the rope-driven method and pulley mechanism layout described in this application, it would still not exceed the scope of protection of this application.

[0101] Based on the above, if the internal motor of the finger is placed as an additional component on the outside of the finger or inside the palm shell, it still does not exceed the protection scope of this application.

Claims

1. A cooperative underactuated robotic hand, characterized in that, include: The palm shell, the limiting structure fixed inside the palm shell, and the transmission and drive components; The transmission assembly includes a slider that is slidably connected to the limiting structure, and a first spring that is fixed at one end to the slider and at the other end as a fixed end. The transmission assembly is provided with four springs. The drive assembly includes a first power source fixed to the palm shell, a limiting member fixed inside the palm shell, and a first rope, a second rope, a third rope, and a fourth rope that are wound and released by the first power source. The first, second, third, and fourth ropes are wound around the limiting member above all the transmission components and are respectively wound around the four sliders and extend upward to connect the fingers. The first spring is used to provide a force to reset the slider connected to itself. When the first power source is wound up, the four ropes are used to pull the fingers to bend. When the first power source is released, the first spring is used to extend the fingers. The four transmission components are arranged from left to right to correspond to the index finger, middle finger, ring finger and little finger respectively. The heights of the four sliders are arranged from high to low as the middle finger slider, index finger slider, ring finger slider and little finger slider. The other end of the first spring corresponding to the little finger faces downward, while the other end of the first spring of the other transmission components faces upward. The first springs corresponding to the little and middle fingers are tension springs, and the first springs corresponding to the ring and index fingers are compression springs. The first rope's driving end moves downwards towards the right side of the slider corresponding to the little finger, then clockwise around to the left and finally extends upwards; the second rope's driving end moves from right to left and downwards, passing over the slider corresponding to the little finger, then clockwise around the bottom right side of the slider corresponding to the ring finger, finally extending upwards; the third rope's driving end moves from right to left and downwards, passing over the slider corresponding to the little finger, then clockwise around the bottom right side of the slider corresponding to the ring finger, then tilts upwards to the left, clockwise around the bottom of the slider corresponding to the middle finger, finally extending upwards; the fourth rope's driving end moves downwards and downwards, passing over the slider corresponding to the little finger, then clockwise around the bottom right side of the slider corresponding to the ring finger, then tilts upwards to the left, counterclockwise around the top right side of the slider corresponding to the middle finger, then tilts downwards to the left, clockwise around the bottom right side of the slider corresponding to the index finger, finally extending upwards; Alternatively, the first spring corresponding to the little finger and ring finger is a tension spring, and the first spring corresponding to the middle finger and index finger is a compression spring; The first rope's driving end moves downwards towards the right side of the slider corresponding to the little finger, then clockwise around to the left, and finally extends upwards. The second rope, in the same manner as the first rope, wraps around the slider corresponding to the little finger, then tilts upwards to the left, clockwise around the bottom of the slider corresponding to the ring finger, and finally extends upwards. The third rope, in the same manner as the first rope, wraps around the slider corresponding to the little finger, then tilts upwards to the left, counterclockwise around the top right side of the slider corresponding to the ring finger, then tilts downwards to the left, clockwise around the bottom right side of the slider corresponding to the middle finger, and finally extends upwards. The fourth rope, in the same manner as the third rope, wraps around the sliders corresponding to the little and ring fingers, passes under the slider corresponding to the middle finger, clockwise around the bottom right side of the slider corresponding to the index finger, and finally extends upwards.

2. The cooperative underactuated robot hand according to claim 1, characterized in that, The limiting structure includes a boss fixed on the palm shell and a cylindrical rod fixed on the boss; the slider includes a base and a guide wheel rotatably connected to the base. Any one of the bases can be inserted into at least two cylindrical rods. When the four guide wheels contact the first rope, the second rope, the third rope and the fourth rope respectively, they are in contact with rolling friction.

3. A finger assembly, characterized in that, Used in conjunction with the cooperative underactuated robot hand as described in claim 1 or 2, the hand includes a base, a first phalanx located above the base, a first connector rotatably connected to the base, a first torsion spring fitted on the first connector, a first wheel rotatably connected to the first connector, the first phalanx rotatably connected to the first connector, and the first torsion spring providing a force for the first phalanx to extend relative to the base. It also includes a second phalanx located above the first phalanx, a second connector rotatably connected to the upper side of the first phalanx, a second torsion spring fitted on the second connector, a second wheel rotatably connected to the second connector, the second phalanx being rotatably connected to the second connector, and the second torsion spring providing a force for the second phalanx to extend relative to the first phalanx; It also includes a third phalanx positioned above the second phalanx, a third connector rotatably connected to the upper side of the second phalanx, a third torsion spring fitted onto the third connector, the third phalanx being rotatably connected to the third connector, and the third torsion spring providing a force for the third phalanx to extend relative to the second phalanx.

4. The finger assembly according to claim 3, characterized in that, The base is fixed to the palm shell, and the first rope, second rope, third rope or fourth rope can be wrapped around the first wheel and second wheel at least once from bottom to top, and fixed on the third finger joint.

5. The finger assembly according to claim 4 further includes a third wheel, which is rotatably connected to or fixed to the third phalanx, and the third wheel supports the first rope, the second rope, the third rope or the fourth rope extending in a forward direction away from the rotation center of the third phalanx.

6. The finger assembly according to claim 5, characterized in that, It also includes a compensation mechanism, which includes a transmission base, a first connecting rod slidably connected to the transmission base, a second connecting rod fixed to the transmission base, one end of a second spring fixed to the transmission base, and the other end of the second spring fixed to the output shaft of a second power source, the second power source being fixedly connected to the first connecting rod; the bottom of the first connecting rod is rotatably connected to a base or a first finger joint; when the bottom of the first connecting rod is rotatably connected to the base, the top of the second connecting rod is rotatably connected to the second finger joint; when the bottom of the first connecting rod is rotatably connected to the first finger joint, the top of the second connecting rod is rotatably connected to the third finger joint.

7. The finger assembly according to claim 3, characterized in that, There are notches formed on the side closer to the bending direction between the first knuckle and the base, between the second knuckle and the first knuckle, and between the third knuckle and the second knuckle, and the sides opposite to the bending direction can be locked together.

8. A multi-finger cooperative underactuated robotic hand, characterized in that, The invention includes the cooperative underactuated robot hand as described in claim 1, and four finger assemblies, the positions of which in the longitudinal direction correspond to the positions of the first rope, the second rope, the third rope, and the fourth rope, respectively, and the first rope, the second rope, the third rope, and the fourth rope are inserted into the four adjacent finger assemblies.

Images