A high-freedom humanoid dexterous hand based on shape memory alloy direct drive

Abstract

The present invention belongs to the field of robotic manipulator technology and discloses a high-degree-of-freedom, humanoid dexterous hand based on direct drive using shape memory alloys. The hand comprises a palm seat and multiple fingers arranged side by side on the palm seat. Each finger includes multiple semiconductor cooling modules, multiple SMA wires, multiple biasing return springs, and multiple interlocking knuckles. Each knuckle is driven to swing by a corresponding semiconductor cooling module and two corresponding SMA wires, and quickly resets due to the biasing return springs. The dexterous hand of the present invention has the advantages of high degree of freedom, good flexibility, rapid response, and lightweight, enabling precise and flexible grasping movements.

Description

Technical Field

[0001] The present invention relates to the technical field of manipulators, and more particularly to a high-freedom humanoid dexterous hand based on shape memory alloy direct drive. Background Art

[0002] In today's rapidly evolving technological landscape, robotics is making significant strides toward greater intelligence and humanization. The development of anthropomorphic dexterous hands has become a highly anticipated frontier. The humanoid dexterous hand holds immense research value, serving not only as a key breakthrough for achieving refined manipulation in robotics but also as a vehicle for humans to expand their capabilities. By mimicking the complex structure and flexible functions of the human hand, the humanoid dexterous hand is expected to play an irreplaceable role in numerous fields, such as assisting elderly individuals with mobility issues with daily object handling and care tasks at home, performing high-risk tasks in hazardous environments, and achieving high-precision assembly and processing in precision manufacturing.

[0003] As an advanced robotic end-effector, the humanoid dexterous hand offers numerous unique advantages over traditional industrial manipulators. It possesses powerful universal grasping capabilities, capable of grasping objects of various shapes and sizes; a wide grasping range, adaptable to a variety of complex scenarios; a rich variety of grasping gestures, high flexibility, and extremely precise in-hand manipulation. As such, the humanoid dexterous hand has found widespread and in-depth application in key areas such as medical equipment, bioengineering, aerospace, and agricultural production, and the development of related technologies has garnered significant attention and recognition from all sectors of society.

[0004] Currently, common dexterous hands are driven by hydraulics, motors, and pneumatics, but these traditional drive methods have some significant drawbacks. Hydraulically driven dexterous hands (such as CN107791266A - a robotic hydraulically driven five-finger dexterous hand) are typically bulky, increasing the overall weight of the device and making operation and maintenance complex and cumbersome. Motor-driven dexterous hands (such as CN107932536A - a humanoid five-finger dexterous hand device and CN119036496A - a direct-drive dexterous hand) are highly rigid and struggle to achieve the same flexible grip as a human hand, limiting their application in scenarios requiring high grip strength and flexibility. Pneumatically driven dexterous hands (such as CN1651200A - a robotic pneumatic dexterous hand) are often accompanied by high noise levels and lack control precision, which to some extent affects their user experience and scope of application.

[0005] In recent years, the emergence of various new functional materials has provided novel solutions for reducing actuator size. Shape memory alloy (SMA) actuators are one such example. SMA actuators are a fundamentally new type of actuator (e.g., CN108284455A - A Humanoid Dexterous Hand Fingers Actuated by SMA Wire). They integrate sensing, control, energy conversion, and actuation, leveraging the unique shape memory effect (SME) of SMA materials to achieve electromechanical energy conversion. SMA actuators are lightweight, have high power density, are simple in structure, and can be easily constructed into microactuators. They offer continuous and smooth motion, operate silently, and are environmentally friendly.

[0006] In the above-mentioned prior art (CN108284455A - A humanoid dexterous hand finger driven by SMA wire), the SMA wire is usually directly connected to a power source for electrical heating, thereby achieving phase change deformation of the SMA wire to drive the finger movement. However, after research, it was found that the method of directly heating the SMA wire with electricity has some defects, such as (1) the cooling and reset of the SMA wire depends on natural cooling, and the cooling process is slow, making it difficult to achieve high reaction speed and high-frequency movement of the finger; (2) when directly heated, the temperature distribution of the SMA wire may be uneven, resulting in inconsistent deformation, and uneven heating may accelerate the initiation of microcracks, causing local stress concentration, causing premature damage to the SMA wire and shortening its service life.

[0007] Therefore, how to provide a high-degree-of-freedom anthropomorphic dexterous hand that can improve finger reaction speed and extend the service life of the dexterous hand is a problem that needs to be solved urgently by those skilled in the art. Summary of the Invention

[0008] In view of this, the present invention provides a high-degree-of-freedom anthropomorphic dexterous hand based on shape memory alloy direct drive, which can improve finger reaction speed and extend the service life of the dexterous hand.

[0009] In order to achieve the above object, the present invention adopts the following technical solutions:

[0010] A high-degree-of-freedom anthropomorphic dexterous hand based on shape memory alloy direct drive, comprising: a palm seat and a plurality of fingers arranged side by side on the palm seat, each finger comprising a plurality of semiconductor cooling modules, a plurality of SMA wires, a plurality of biasing return springs, and a plurality of mutually hinged knuckles, each knuckle being driven to swing by a corresponding semiconductor cooling module and two corresponding SMA wires;

[0011] In which, the hot and cold ends of the semiconductor refrigeration module are respectively arranged opposite to the corresponding two SMA wires, and the semiconductor refrigeration module is connected to a power supply, which is used to pass current to the semiconductor refrigeration module, so that the hot end on it heats up one of the SMA wires to cause it to contract, and the cold end of the semiconductor refrigeration module cools down the other SMA wire to cause it to stretch, thereby realizing the swing of the corresponding knuckles, and the current direction of the semiconductor refrigeration module is changed by the power supply, thereby exchanging the hot and cold ends of the semiconductor refrigeration module. At this time, the cold end of the exchanged semiconductor refrigeration module cools down one of the SMA wires to cause it to stretch, and the hot end of the exchanged semiconductor refrigeration module heats up the other SMA wire to cause it to contract, thereby realizing the reset of the corresponding knuckles, and accelerating the reset of the knuckles under the action of the bias reset spring.

[0012] As can be seen from the above technical solutions, compared to the prior art, the present invention provides a high-degree-of-freedom anthropomorphic dexterous hand based on direct drive of shape memory alloys. This dexterous hand indirectly heats and cools the SMA wire through a semiconductor cooling module, avoiding the existing problems of uneven temperature distribution and inconsistent deformation caused by direct electrical heating of the SMA wire. Furthermore, uneven heating can accelerate the initiation of microcracks in the SMA wire, causing local stress concentration and premature damage to the SMA wire, shortening its service life. Furthermore, the use of a semiconductor cooling module can achieve active cooling of the SMA wire, avoiding the existing problems of slow cooling caused by the SMA wire's reliance on natural cooling, which makes it difficult to achieve high finger reaction speeds and high-frequency movements. Furthermore, the use of a biased return spring can accelerate finger return, avoiding the problem of delayed finger return due to the required cooling time required by the semiconductor cooling module to cool the SMA wire. Furthermore, each knuckle on the finger of this dexterous hand is independently matched with a semiconductor cooling module and SMA wire, allowing the movement of each knuckle to be independently controlled without affecting each other, thereby improving the finger's flexibility and high degree of freedom. In addition, each knuckle is driven by two independent SMA wires. This avoids the problem of reduced sensitivity of the knuckles due to the mutual interference of the hot and cold on one SMA wire when the knuckles are heated and cooled by the semiconductor refrigeration module, which prevents the SMA wire from quickly heating and cooling.

[0013] Therefore, the dexterous hand of the present invention has the advantages of high degree of freedom, good flexibility and rapid response, and can achieve fine and flexible grasping movements.

[0014] Furthermore, the plurality of fingers are respectively a thumb, an index finger, a middle finger, a ring finger, and a little finger, and the structures of the index finger, the middle finger, the ring finger, and the little finger are all the same;

[0015] The multiple knuckles on the thumb are respectively: a first knuckle, a second knuckle, a third knuckle, and a fourth knuckle; the multiple semiconductor refrigeration modules on the thumb are respectively a first semiconductor refrigeration module, a second semiconductor refrigeration module, and a third semiconductor refrigeration module; the multiple SMA wires on the thumb are respectively a first SMA wire, a second SMA wire, and a third SMA wire; the multiple bias return springs on the thumb are respectively a first bias return spring, a second bias return spring, and a third bias return spring;

[0016] The top of the first knuckle is hinged to the bottom of the second knuckle via a joint axis; the second knuckle is provided with two first pulleys arranged at intervals, each of the two first pulleys being wound with a first SMA wire, both ends of the two first SMA wires being fixed to the first knuckle; the first knuckle is provided with a first semiconductor refrigeration module, the hot and cold ends of the first semiconductor refrigeration module being arranged opposite to the two first SMA wires, respectively; the power supply supplies current to the first semiconductor refrigeration module, thereby causing the first SMA wire to drive the second knuckle to swing left and right; and the first bias return spring is fixed to the left and right side walls of the first and second knuckles;

[0017] The top of the second knuckle is hinged to the bottom of the third knuckle via a joint axis; the third knuckle is provided with two second pulleys arranged at intervals, each of the two second pulleys being wound with a second SMA wire, both ends of the two second SMA wires being fixed to the first knuckle; a second semiconductor refrigeration module is provided in the first knuckle, and the hot and cold ends of the second semiconductor refrigeration module are respectively arranged opposite to the two second SMA wires; the power supply supplies current to the second semiconductor refrigeration module, thereby enabling the second SMA wire to drive the third knuckle to swing toward the inner side of the palm seat; a second bias return spring is fixed to the outer side walls of the second knuckle and the third knuckle;

[0018] The top of the third knuckle is hinged to the bottom of the fourth knuckle through a joint axis, two third pulleys arranged at intervals are provided on the fourth knuckle, the third SMA wire is wound around the two third pulleys, both ends of the two third SMA wires are fixed to the third knuckle, the third knuckle is provided with a third semiconductor refrigeration module, the hot and cold ends of the third semiconductor refrigeration module are respectively arranged opposite to the two third SMA wires, the power supply supplies current to the third semiconductor refrigeration module, thereby enabling the third SMA wire to drive the fourth knuckle to swing toward the inner side of the palm seat, and the third bias return spring is fixed to the outer side walls of the third knuckle and the fourth knuckle;

[0019] The knuckles on the index finger and the thumb have the same arrangement structure but different numbers of knuckles.

[0020] Furthermore, the knuckles on the thumb further include a fifth knuckle turned inward toward the inner side of the palm seat, the semiconductor refrigeration module on the thumb further includes a fourth semiconductor refrigeration module, the SMA wire on the thumb further includes a fourth SMA wire, and the bias return spring on the thumb further includes a fourth bias return spring;

[0021] The bottom of the first knuckle is fixedly connected to the fifth knuckle, the fifth knuckle and the palm seat are hinged by a joint axis, fourth pulleys are provided on the two opposite side walls of the fifth knuckle, the two fourth pulleys are wound with the fourth SMA wire, both ends of the two fourth SMA wires are fixed in the palm seat, a fourth semiconductor refrigeration module is provided in the palm seat, the hot and cold ends of the fourth semiconductor refrigeration module are respectively arranged opposite to the two fourth SMA wires, the power supply supplies current to the fourth semiconductor refrigeration module, thereby realizing the fourth SMA wire driving the fifth knuckle to turn inward toward the inner side of the palm seat, and the fourth bias return spring is fixed on the outer side walls of the fifth knuckle and the palm seat.

[0022] The beneficial effect of adopting the above technical solution is that the knuckles are driven by the corresponding semiconductor refrigeration module and two SMA wires, so that the degrees of freedom of the dexterous hand can reach 20 degrees of freedom (thumb + index finger + middle finger + ring finger + little finger: 4+4+4+4+4=20 degrees of freedom), which is basically close to the 21 degrees of freedom of the human hand, that is, the thumb can have the functions of inversion, inward swing (bending inward toward the palm), and left and right swing (opening and closing of fingers), and the index finger, middle finger, ring finger, and little finger have the functions of inward swing (bending inward toward the palm) and left and right swing (opening and closing of fingers), so that the dexterous hand can smoothly complete the bending and opening and closing movements.

[0023] Furthermore, the first biasing return spring, the second biasing return spring, the third biasing return spring, and the fourth biasing return spring on each side are arranged in twos at intervals.

[0024] The beneficial effect of adopting the above technical solution is that the use of two biased return springs can make the finger joint reset more stable and greatly improve the rapidity of the finger joint reset.

[0025] Furthermore, it also includes a controller and an angle sensor. The thumb is provided with the angle sensor for detecting the rotation angle of the joint axis. The controller controls the current parameters of the power supply in real time according to the data of the angle sensor to control the temperature increase or decrease of the semiconductor refrigeration module.

[0026] The beneficial effects of adopting the above technical solution are: the angle sensor collects the rotation angle of the knuckle in real time and transmits it to the controller. The controller compares the actual angle with the target angle and adjusts the TEC (semiconductor refrigeration module) temperature control according to the deviation (for example, if the angle is insufficient, the TEC temperature is controlled to increase, causing the SMA wire to further contract; if the angle is overshoot, the TEC temperature is controlled to cool down and the SMA wire to relax and return to its original position), forming a closed-loop control, thereby ensuring the accuracy of the knuckle movement.

[0027] Furthermore, the SMA wire has two-way shape memory properties or one-way shape memory properties. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are merely embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on the provided drawings without paying any creative work.

[0029] Figure 1 This is a schematic diagram of the three-dimensional structure of a high-freedom anthropomorphic dexterous hand based on shape memory alloy direct drive provided by the present invention.

[0030] Figure 2 for Figure 1 Schematic diagram of the main structure.

[0031] Figure 3 for Figure 1 Schematic diagram of the rear view structure.

[0032] Figure 4 for Figure 3 Schematic cross-section of the middle section AA.

[0033] Figure 5 for Figure 1 Schematic diagram of the side structure.

[0034] Figure 6 for Figure 1 Schematic diagram of the top view structure.

[0035] Figure 7 Schematic diagram of the three-dimensional structure of the thumb.

[0036] Figure 8 for Figure 7 Schematic diagram of the main structure.

[0037] Figure 9 for Figure 8 Schematic cross-section of the middle section BB.

[0038] Figure 10 for Figure 7Schematic diagram of the side structure.

[0039] Figure 11 for Figure 10 Schematic cross-section of the center section CC.

[0040] Figure 12 for Figure 7 Schematic diagram of the rear view structure.

[0041] Figure 13 Schematic diagram of the three-dimensional structure of the index finger.

[0042] Figure 14 for Figure 13 Schematic diagram of the main structure.

[0043] Figure 15 for Figure 14 Schematic cross-section of the middle section DD.

[0044] Figure 16 This is a schematic diagram of the control part of a high-freedom anthropomorphic dexterous hand based on shape memory alloy direct drive provided by the present invention.

[0045] Figure 17 This is a control logic diagram of a high-freedom anthropomorphic dexterous hand based on shape memory alloy direct drive provided by the present invention. DETAILED DESCRIPTION

[0046] The following describes embodiments of the present invention in detail, examples of which are shown in the accompanying drawings, wherein the same or similar reference numerals throughout represent the same or similar elements or elements having the same or similar functions. The embodiments described below with reference to the accompanying drawings are exemplary and are intended to be used to explain the present invention, and are not to be construed as limiting the present invention.

[0047] In the description of the present invention, it should be understood that the terms "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", etc., indicating directions or positional relationships, are based on the directions or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific direction, be constructed and operated in a specific direction, and therefore should not be understood as limiting the present invention.

[0048] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be understood to indicate or imply relative importance or implicitly specify the number of the technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of the features. In the description of the present invention, "plurality" means two or more, and "multiple" means two or more, unless otherwise specifically defined.

[0049] In the present invention, unless otherwise expressly specified or limited, the terms "mounted," "connected," "connect," "fixed," etc. should be understood broadly. For example, they may refer to fixed connection, detachable connection, or integration; mechanical connection or electrical connection; direct connection or indirect connection through an intermediate medium; internal communication between two components or interaction between two components. Those skilled in the art will understand the specific meanings of the above terms in the present invention based on specific circumstances.

[0050] See also Figures 1-17 As shown, an embodiment of the present invention discloses a high-degree-of-freedom anthropomorphic dexterous hand based on shape memory alloy direct drive, comprising: a palm seat 1 and a plurality of fingers 2 arranged side by side on the palm seat 1, each finger 2 comprising a plurality of semiconductor cooling modules 3, a plurality of SMA wires 4, a plurality of bias return springs 5, and a plurality of mutually hinged finger joints 6, each finger joint 6 being driven to swing by a corresponding semiconductor cooling module 3 and two corresponding SMA wires 4; wherein each semiconductor cooling module 3 is composed of a semiconductor cooling plate and a housing;

[0051] Among them, the hot and cold ends of the semiconductor refrigeration module 3 are arranged opposite to the corresponding two SMA wires 4 respectively, and the semiconductor refrigeration module 3 is connected to a power supply 7. The power supply 7 is used to pass current to the semiconductor refrigeration module 3, so that the hot end on it heats up one of the SMA wires 4 to make it contract, and the cold end of the semiconductor refrigeration module 3 cools down the other SMA wire 4 to make it stretch, thereby realizing the swing of the corresponding finger joint 6, and the current direction of the semiconductor refrigeration module 3 is changed by the power supply 7, thereby making the hot and cold ends of the semiconductor refrigeration module 3 exchanged. At this time, the cold end of the exchanged semiconductor refrigeration module 3 cools down one of the SMA wires 4 to make it stretch, and the hot end of the exchanged semiconductor refrigeration module 3 heats up the other SMA wire 4 to make it contract, thereby realizing the reset of the corresponding finger joint 6, and accelerating the reset of the finger joint 6 under the action of the bias reset spring 5.

[0052] The plurality of fingers 2 are respectively a thumb 21, an index finger 22, a middle finger 23, a ring finger 24, and a little finger 25, and the structures of the index finger 22, the middle finger 23, the ring finger 24, and the little finger 25 are all the same;

[0053] The multiple knuckles 6 on the thumb 21 are respectively: a first knuckle 61, a second knuckle 62, a third knuckle 63, and a fourth knuckle 64; the multiple semiconductor refrigeration modules 3 on the thumb 21 are respectively: a first semiconductor refrigeration module 31, a second semiconductor refrigeration module 32, and a third semiconductor refrigeration module 33; the multiple SMA wires 4 on the thumb 21 are respectively: a first SMA wire 41, a second SMA wire 42, and a third SMA wire 43; the multiple bias return springs 5 ​​on the thumb 21 are respectively: a first bias return spring 51, a second bias return spring 52, and a third bias return spring 53;

[0054] The top of the first finger joint 61 is hinged to the bottom of the second finger joint 62 via a joint shaft 8. The second finger joint 62 is provided with two first pulleys 9 arranged at intervals. The two first pulleys 9 are each wound with a first SMA wire 41. Both ends of the two first SMA wires 41 are fixed to the first finger joint 61. A first semiconductor refrigeration module 31 is provided in the first finger joint 61. The hot and cold ends of the first semiconductor refrigeration module 31 are respectively arranged opposite to the two first SMA wires 41. The power supply 7 supplies current to the first semiconductor refrigeration module 31, thereby causing the first SMA wire 41 to drive the second finger joint 62 to swing left and right. First bias return springs 51 are fixed to the left and right side walls of the first finger joint 61 and the second finger joint 62.

[0055] The top of the second knuckle 62 is hinged to the bottom of the third knuckle 63 via a joint shaft 8. The third knuckle 63 is provided with two spaced second pulleys 10. A second SMA wire 42 is wound around each of the two second pulleys 10. Both ends of the two second SMA wires 42 are fixed to the first knuckle 61. A second semiconductor refrigeration module 32 is provided in the first knuckle 61. The hot and cold ends of the second semiconductor refrigeration module 32 are respectively arranged opposite to the two second SMA wires 42. The power supply 7 supplies current to the second semiconductor refrigeration module 32, thereby causing the second SMA wire 42 to drive the third knuckle 63 to swing toward the inner side of the palm seat 1. A second bias return spring 52 is fixed to the outer side walls of the second knuckle 62 and the third knuckle 63.

[0056] The top of the third finger joint 63 is hinged to the bottom of the fourth finger joint 64 through the joint shaft 8. The fourth finger joint 64 is provided with two spaced third pulleys 11. A third SMA wire 43 is wound around each of the two third pulleys 11. Both ends of the two third SMA wires 43 are fixed to the third finger joint 63. A third semiconductor refrigeration module 33 is provided in the third finger joint 63. The hot and cold ends of the third semiconductor refrigeration module 33 are respectively arranged opposite to the two third SMA wires 43. The power supply 7 supplies current to the third semiconductor refrigeration module 33, thereby causing the third SMA wire 43 to drive the fourth finger joint 64 to swing toward the inner side of the palm seat 1. A third bias return spring 53 is fixed to the outer side walls of the third finger joint 63 and the fourth finger joint 64.

[0057] The knuckles on the index finger 22 and the thumb 21 have the same arrangement structure but different numbers of knuckles.

[0058] The knuckle 6 on the thumb 21 further includes a fifth knuckle 65 turned inward toward the inner side of the palm seat 1 . The semiconductor cooling module 3 on the thumb 21 further includes a fourth semiconductor cooling module 34 . The SMA wire 4 on the thumb 21 further includes a fourth SMA wire 44 . The bias return spring 5 on the thumb 21 further includes a fourth bias return spring 54 .

[0059] The bottom of the first finger joint 61 is fixedly connected to the fifth finger joint 65, and the fifth finger joint 65 and the palm seat 1 are hinged by a joint shaft 8. Fourth pulleys 12 are provided on the two opposite side walls of the fifth finger joint 65, and fourth SMA wires 44 are wound around the two fourth pulleys 12. Both ends of the two fourth SMA wires 44 are fixed in the palm seat 1. A fourth semiconductor refrigeration module 34 is provided in the palm seat 1, and the hot and cold ends of the fourth semiconductor refrigeration module 34 are respectively arranged opposite to the two fourth SMA wires 44. The power supply 7 supplies current to the fourth semiconductor refrigeration module 34, thereby realizing that the fourth SMA wire 44 drives the fifth finger joint 65 to turn inward toward the inner side of the palm seat 1, and a fourth bias return spring 54 is fixed on the outer side wall of the fifth finger joint 65 and the palm seat 1.

[0060] On each side, two first bias return springs 51 , second bias return springs 52 , third bias return springs 53 , and fourth bias return springs 54 are arranged at intervals.

[0061] The high-degree-of-freedom anthropomorphic dexterous hand based on shape memory alloy direct drive also includes a controller 13 and an angle sensor 14. The thumb 21 is provided with an angle sensor 14 for detecting the rotation angle of the joint shaft 8. The controller 13 controls the current parameters of the power supply 7 in real time according to the data of the angle sensor 14 to control the temperature increase or decrease of the semiconductor refrigeration module 3.

[0062] like Figure 17 As shown, the PID (Proportional-Integral-Derivative) control algorithm can be incorporated into the controller. The proportional term quickly responds to deviations, the integral term eliminates steady-state errors, and the differential term predicts trends. Fuzzy control can also be combined to address complex characteristics such as SMA nonlinearity and TEC thermal inertia, optimizing control accuracy and response speed. Other control algorithms can also be used, such as neural network PID, sliding mode control (SMC), multi-processor predictive control (MPC), integral separation PID, and fuzzy PID.

[0063] In addition, the power supply 7 and the controller 13 of the present invention can be mounted on the outside of the palm seat 1 of the dexterous hand, or on the body of a robot used in conjunction with the dexterous hand.

[0064] The SMA wire 4 is a one-way shape memory alloy wire or a two-way shape memory alloy wire.

[0065] The basic principle of the Peltier effect is that when current flows through a conductor, charge carriers jump between energy levels of different materials, resulting in energy exchange. When a charge carrier jumps from a higher energy level to a lower energy level, it releases energy, which manifests as heat release; conversely, when jumping from a lower energy level to a higher energy level, it needs to absorb energy from the outside world, which manifests as heat absorption. This energy exchange manifests as heat at the joints of the conductors.

[0066] An important application of the Peltier effect is the semiconductor cooler (TEC), also known as a thermoelectric cooler, temperature differential cooler, or semiconductor cooling module. This type of cooler uses the Peltier effect to control the direction of current flow to achieve cooling or heating at the node. Because semiconductor coolers have no refrigerants or moving parts, they have the advantages of precise temperature control, no noise, and high reliability.

[0067] TEC temperature control logic: The TEC semiconductor cooling module controls temperature rise and fall by controlling the direction and magnitude of the current. During temperature rise, the controlled current causes the TEC to supply heat to the SMA wire, causing the wire to undergo a phase change and shape memory deformation, resulting in contraction. During temperature drop, the current direction and parameters are changed, allowing the TEC to absorb heat from the SMA, lowering the SMA temperature and driving a reverse phase change, causing the SMA to elongate.

[0068] Therefore, the driving mode of the dexterous hand of the present invention is designed based on shape memory characteristics and Peltier effect.

[0069] The index finger 22, middle finger 23, ring finger 24, and little finger 25 of the present invention have the same knuckle arrangement structure as the thumb 21, but the number of knuckles is different, that is, the index finger 22, middle finger 23, ring finger 24, and little finger 25 have one more knuckle than the thumb 21 (except for the fifth knuckle 65 with inversion function), see Figure 1 As shown, therefore, the present invention mainly explains the working principle of the thumb as follows:

[0070] The second phalanx 62 opens and closes and returns to its original position (see Figure 11 ):

[0071] The second finger joint 62 swings to the left and resets as follows: the controller 13 controls the power supply 7 to pass current to the first semiconductor refrigeration module 31, so that the hot end of the first semiconductor refrigeration module 31 heats up the first SMA wire 41 on the left side to cause it to contract. At this time, the cold end of the first semiconductor refrigeration module 31 cools down the first SMA wire 41 on the right side to cause it to stretch, thereby achieving the second finger joint 62 to swing to the left. At this time, the first bias return spring 51 on the left side is compressed and the first bias return spring 51 on the right side is extended. During reset, the controller 13 controls the power supply 7 to change the current direction of the first semiconductor refrigeration module 31, thereby swapping the hot and cold ends of the first semiconductor refrigeration module 31. At this time, the cold end of the swapped first semiconductor refrigeration module 31 cools down the first SMA wire 41 on the left side to cause it to stretch. The hot end of the swapped first semiconductor refrigeration module 31 heats up the first SMA wire 41 on the right side to cause it to contract, thereby achieving the second finger joint 62 swinging to the right and resetting. Under the action of the first bias return spring 51 on the left and the first bias return spring 51 on the right, the second finger joint 62 is quickly reset.

[0072] The second finger joint 62 swings to the right and resets in the following process: the controller 13 controls the power supply 7 to change the current direction of the first semiconductor refrigeration module 31, thereby exchanging the hot and cold ends of the first semiconductor refrigeration module 31. At this time, the cold end of the exchanged first semiconductor refrigeration module 31 cools down the first SMA wire 41 on the left side to make it stretch, and the hot end of the exchanged first semiconductor refrigeration module 31 heats up the first SMA wire 41 on the right side to make it contract, thereby achieving the second finger joint 62 swinging to the right. At this time, the first bias return spring 51 on the left side is extended, and the first bias return spring 51 on the right side is compressed; reset When the first semiconductor refrigeration module 31 is in the left position, the controller 13 controls the power supply 7 to change the current direction of the first semiconductor refrigeration module 31 again, thereby exchanging the hot and cold ends of the first semiconductor refrigeration module 31. At this time, the cold end of the exchanged first semiconductor refrigeration module 31 heats up the first SMA wire 41 on the left side to cause it to contract, and the hot end of the exchanged first semiconductor refrigeration module 31 cools down the first SMA wire 41 on the right side to cause it to expand, thereby achieving the second finger joint 62 to swing back to the left side, and the second finger joint 62 is quickly reset under the action of the first bias return spring 51 on the left side and the first bias return spring 51 on the right side;

[0073] The process of bending and repositioning the third phalanx 63 toward the palm (see Figure 9 ):

[0074] The controller 13 controls the power supply 7 to pass current to the second semiconductor refrigeration module 32, so that the hot end of the second semiconductor refrigeration module 32 heats up the second SMA wire 42 on the left side to cause it to contract. At this time, the cold end of the second semiconductor refrigeration module 32 cools down the second SMA wire 42 on the right side to cause it to stretch, thereby causing the third finger joint 63 to swing to the left, that is, bend toward the palm. At this time, the second bias return spring 52 on the right side extends. During reset, the controller 13 controls the power supply 7 to change the current direction of the second semiconductor refrigeration module 32, thereby exchanging the hot and cold ends of the second semiconductor refrigeration module 32. At this time, the cold end of the exchanged second semiconductor refrigeration module 32 cools down the second SMA wire 42 on the left side to cause it to stretch, and the hot end of the exchanged second semiconductor refrigeration module 32 heats up the second SMA wire 42 on the right side to cause it to contract, thereby causing the third finger joint 63 to swing to the right side and reset. The third finger joint 63 is quickly reset under the pull of the second bias return spring 52 on the right side.

[0075] The process of bending and repositioning the fourth phalanx 64 toward the palm (see Figure 9 ):

[0076] The controller 13 controls the power supply 7 to pass current to the third semiconductor refrigeration module 33, so that the hot end of the third semiconductor refrigeration module 33 heats up the third SMA wire 43 on the left side to cause it to contract. At this time, the cold end of the third semiconductor refrigeration module 33 cools down the third SMA wire 43 on the right side to cause it to stretch, thereby causing the fourth finger joint 64 to swing to the left, that is, bend toward the palm. At this time, the third bias return spring 53 on the right side extends. During reset, the controller 13 controls the power supply 7 to change the current direction of the third semiconductor refrigeration module 33, thereby exchanging the hot and cold ends of the third semiconductor refrigeration module 33. At this time, the cold end of the exchanged third semiconductor refrigeration module 33 cools down the third SMA wire 43 on the left side to cause it to stretch, and the hot end of the exchanged third semiconductor refrigeration module 33 heats up the third SMA wire 43 on the right side to cause it to contract, thereby causing the fourth finger joint 64 to swing to the right side to reset, and the fourth finger joint 64 is quickly reset under the pull of the third bias return spring 53 on the right side.

[0077] The process of inversion and reduction of the fifth phalanx 65 (see Figure 4 ):

[0078] The controller 13 controls the power supply 7 to pass current through the fourth semiconductor refrigeration module 34, causing the hot end of the fourth semiconductor refrigeration module 34 to heat the fourth SMA wire 44 on the lower side, causing it to contract. At this time, the cold end of the fourth semiconductor refrigeration module 34 cools the fourth SMA wire 44 on the upper side, causing it to stretch, thereby causing the fifth finger joint 65 to swing downward (i.e., turn inward toward the palm). At this time, the fourth bias return spring 54 on the upper side extends. During reset, the controller 13 controls the power supply 7 to change the direction of current flow through the fourth semiconductor refrigeration module 34, thereby swapping the hot and cold ends of the fourth semiconductor refrigeration module 34. At this time, the cold end of the swapped fourth semiconductor refrigeration module 34 cools the fourth SMA wire 44 on the lower side, causing it to stretch, while the hot end of the swapped fourth semiconductor refrigeration module 34 heats the fourth SMA wire 44 on the upper side, causing it to contract, thereby causing the fifth finger joint 65 to swing upward and reset (i.e., swing away from the palm). The fifth finger joint 65 is quickly reset under the pull of the fourth bias return spring 54 on the upper side.

[0079] The present invention can control the current direction and magnitude of the power supply through a controller, thereby controlling the exchange of the hot and cold ends of the semiconductor refrigeration module and the bending angle of the knuckles.

[0080] In addition, it should be noted that the present invention takes into account that using a fan to cool the SMA wire is not only noisy but also takes up a lot of space. Therefore, the fan cooling solution is not suitable. Therefore, the present invention uses a semiconductor refrigeration module that can be applied to space constraints as the heating and cooling component of the SMA wire. In this way, the SMA wire is indirectly heated and cooled by the semiconductor refrigeration module, which can avoid the existing problem of uneven temperature distribution of the SMA wire caused by direct electrical heating of the SMA wire, resulting in inconsistent deformation. The uneven heating may also accelerate the initiation of microcracks in the SMA wire, causing local stress concentration, causing premature damage to the SMA wire and shortening its service life. Moreover, the use of the semiconductor refrigeration module is suitable for installation in small joint spaces and can also achieve active cooling of the SMA wire, thereby accelerating the transformation of the SMA wire from austenite to martensite, further improving the speed of finger reaction.

[0081] The various embodiments in this specification are described in a progressive manner, with each embodiment focusing on the differences from other embodiments. Reference can be made to the common and similar parts between the various embodiments. For the devices disclosed in the embodiments, since they correspond to the methods disclosed in the embodiments, the description is relatively simple, and the relevant parts can be referred to the method description.

[0082] The above description of the disclosed embodiments is intended to enable one skilled in the art to implement or use the present invention. Various modifications to these embodiments will be readily apparent to one skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the present invention. Therefore, the present invention is not limited to the embodiments shown herein but is intended to conform to the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A high degree of freedom humanoid dexterous hand based on shape memory alloy direct drive, characterized by: include: A palm seat (1) and a plurality of fingers (2) arranged side by side on the palm seat (1), each of the fingers (2) comprising a plurality of semiconductor cooling modules (3), a plurality of SMA wires (4), a plurality of biasing return springs (5), and a plurality of finger joints (6) hinged to each other, each of the finger joints (6) being driven to swing by a corresponding semiconductor cooling module (3) and corresponding two SMA wires (4); The hot and cold ends of the semiconductor refrigeration module (3) are respectively arranged relative to the corresponding two SMA wires (4), and the semiconductor refrigeration module (3) is connected to a power supply (7). The power supply (7) is used to pass current through the semiconductor refrigeration module (3), so that the hot end on it heats up one of the SMA wires (4) to make it shrink, and the cold end of the semiconductor refrigeration module (3) cools down the other SMA wire (4) to make it stretch, thereby realizing the swing of the corresponding finger joint (6), and the current direction of the semiconductor refrigeration module (3) is changed by the power supply (7), thereby making the hot and cold ends of the semiconductor refrigeration module (3) exchanged. At this time, the cold end of the semiconductor refrigeration module (3) after the exchange cools down one of the SMA wires (4) to make it stretch, and the hot end of the semiconductor refrigeration module (3) after the exchange heats up the other SMA wire (4) to make it shrink, thereby realizing the reset of the corresponding finger joint (6), and accelerating the reset of the finger joint (6) under the action of the bias reset spring (5).

2. The high-freedom humanoid dexterous hand based on shape memory alloy direct drive according to claim 1, characterized in that: The plurality of fingers (2) are respectively a thumb (21), an index finger (22), a middle finger (23), a ring finger (24), and a little finger (25); the structures of the index finger (22), the middle finger (23), the ring finger (24), and the little finger (25) are all the same; The multiple knuckles (6) on the thumb (21) are respectively: a first knuckle (61), a second knuckle (62), a third knuckle (63), and a fourth knuckle (64); the multiple semiconductor refrigeration modules (3) on the thumb (21) are respectively: a first semiconductor refrigeration module (31), a second semiconductor refrigeration module (32), and a third semiconductor refrigeration module (33); the multiple SMA wires (4) on the thumb (21) are respectively: a first SMA wire (41), a second SMA wire (42), and a third SMA wire (43); the multiple bias return springs (5) on the thumb (21) are respectively: a first bias return spring (51), a second bias return spring (52), and a third bias return spring (53); The top of the first finger joint (61) is hinged to the bottom of the second finger joint (62) through a joint shaft (8); the second finger joint (62) is provided with two first pulleys (9) arranged at intervals; the two first pulleys (9) are both wound with the first SMA wire (41); both ends of the two first SMA wires (41) are fixed to the first finger joint (61); the first semiconductor refrigeration module (31) is provided in the first finger joint (61); the hot and cold ends of the first semiconductor refrigeration module (31) are respectively arranged opposite to the two first SMA wires (41); the power supply (7) supplies current to the first semiconductor refrigeration module (31) so that the first SMA wire (41) drives the second finger joint (62) to swing left and right; the first bias return spring (51) is fixed to the left and right side walls of the first finger joint (61) and the second finger joint (62); The top of the second finger joint (62) is hinged to the bottom of the third finger joint (63) through a joint shaft (8); the third finger joint (63) is provided with two second pulleys (10) arranged at intervals; the two second pulleys (10) are wound with the second SMA wire (42); both ends of the two second SMA wires (42) are fixed to the first finger joint (61); the first finger joint (61) is provided with a second semiconductor refrigeration module (32); the hot and cold ends of the second semiconductor refrigeration module (32) are respectively arranged opposite to the two second SMA wires (42); the power supply (7) supplies current to the second semiconductor refrigeration module (32) so that the second SMA wire (42) drives the third finger joint (63) to swing toward the inner side of the palm seat (1); the second bias return spring (52) is fixed to the outer side walls of the second finger joint (62) and the third finger joint (63); The top of the third finger joint (63) is hinged to the bottom of the fourth finger joint (64) through a joint shaft (8); two third pulleys (11) arranged at intervals are provided on the fourth finger joint (64); the third SMA wire (43) is wound around the two third pulleys (11); both ends of the two third SMA wires (43) are fixed to the third finger joint (63); the third semiconductor refrigeration module (33) is provided in the third finger joint (63); the hot and cold ends of the third semiconductor refrigeration module (33) are arranged opposite to the two third SMA wires (43); the power supply (7) supplies current to the third semiconductor refrigeration module (33) so that the third SMA wire (43) drives the fourth finger joint (64) to swing toward the inner side of the palm seat (1); the third bias return spring (53) is fixed on the outer side walls of the third finger joint (63) and the fourth finger joint (64); The index finger (22) and the thumb (21) have the same knuckle arrangement structure but different numbers of knuckles.

3. The high-freedom humanoid dexterous hand based on shape memory alloy direct drive according to claim 2, characterized in that: The knuckle (6) on the thumb (21) further includes a fifth knuckle (65) turned inward toward the inner side of the palm seat (1), the semiconductor refrigeration module (3) on the thumb (21) further includes a fourth semiconductor refrigeration module (34), the SMA wire (4) on the thumb (21) further includes a fourth SMA wire (44), and the bias return spring (5) on the thumb (21) further includes a fourth bias return spring (54); The bottom of the first finger joint (61) is fixedly connected to the fifth finger joint (65), and the fifth finger joint (65) and the palm seat (1) are hinged via a joint shaft (8). A fourth pulley (12) is provided on two opposite side walls of the fifth finger joint (65), and the fourth SMA wire (44) is wound around the two fourth pulleys (12). Both ends of the two fourth SMA wires (44) are fixed in the palm seat (1), and a fourth semi-conductor is provided in the palm seat (1). The fourth semiconductor refrigeration module (34) has hot and cold ends arranged opposite to the two fourth SMA wires (44), the power supply (7) supplies current to the fourth semiconductor refrigeration module (34), thereby enabling the fourth SMA wire (44) to drive the fifth finger joint (65) to turn inward toward the inner side of the palm seat (1), and the fourth bias return spring (54) is fixed on the outer side wall of the fifth finger joint (65) and the palm seat (1).

4. The high-freedom humanoid dexterous hand based on shape memory alloy direct drive according to claim 3, characterized in that: The first bias return spring (51), the second bias return spring (52), the third bias return spring (53), and the fourth bias return spring (54) on each side are arranged in pairs at intervals.

5. The high-degree-of-freedom humanoid dexterous hand based on shape memory alloy direct drive according to any one of claims 2 to 4, characterized in that: The invention also includes a controller (13) and an angle sensor (14). The thumb (21) is provided with the angle sensor (14) for detecting the rotation angle of the joint shaft (8). The controller (13) controls the current parameters of the power supply (7) in real time according to the data of the angle sensor (14) to control the temperature increase or decrease of the semiconductor refrigeration module (3).

6. A high-degree-of-freedom anthropomorphic dexterous hand based on shape memory alloy direct drive according to any one of claims 1 to 4, wherein the SMA wire (4) has a two-way shape memory property or a one-way shape memory property.

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