Thumb movement mechanism of humanoid dexterous hand

Abstract

The utility model provides a thumb movement mechanism of a humanoid dexterous hand. The thumb movement mechanism comprises a palm, a joint mechanism, a first hinge shaft and a second hinge shaft. One end of the palm is connected with four fingers, the joint mechanism is arranged in the palm, one side of the joint mechanism extends out of the palm, and the palm is connected with a thumb through the joint mechanism. A thumb linear driver is arranged in the palm and used for controlling the joint mechanism to drive the thumb to bend and swing laterally. The coupling connecting rod movement mechanism is adopted in the thumb to achieve bending of the thumb, the structure is simple, maintenance is convenient, the failure rate of the thumb movement mechanism in use is reduced, the layout of the thumb linear drivers is changed, the linear drivers used for driving the thumb to bend are all arranged on the palm, and therefore the flexibility of the thumb movement mechanism is improved. The size of the thumb near knuckles is reduced, and the flexibility of the dexterous hand is improved.

Description

Technical Field

[0001] This utility model relates to the field of robotics technology, and more specifically, to a thumb movement mechanism for a humanoid dexterous hand. Background Technology

[0002] A robotic arm is an automated operating device that can mimic certain movements and functions of a human hand and arm to grasp, move objects, or operate tools according to a fixed program. The characteristic of a robotic arm is that it can be programmed to complete various expected tasks, and its structure and performance combine the advantages of both humans and machines.

[0003] In existing technologies, the thumb mechanism of a humanoid dexterous hand can generally achieve the functions of bending and lateral swinging. In order to achieve these two degrees of freedom, two linear drive mechanisms are used to drive it separately, so as to achieve actions similar to human fingers grasping and releasing.

[0004] However, existing robotic hand structures, when driving thumb movements, either use rope-driven structures, resulting in complex structures, high failure rates, and difficulty in maintenance; or one of the linear drive mechanisms is directly arranged at the proximal joint of the thumb to achieve the thumb's bending function. For some humanoid dexterous hands that require large clamping forces, the linear drive mechanism is relatively large, which leads to a large proximal joint of the thumb. As a result, for a single thumb, the distal, middle, and proximal joints are difficult to coordinate to clamp objects, which will interfere with the thumb's clamping action.

[0005] Therefore, how to improve the structural reliability of the thumb in a dexterous hand is a problem that urgently needs to be solved by those skilled in the art. Summary of the Invention

[0006] To address the aforementioned problems, the purpose of this utility model embodiment is to provide a thumb movement mechanism that mimics a human dexterous hand.

[0007] This utility model embodiment provides a thumb movement mechanism for a humanoid dexterous hand, including: a palm, a joint mechanism, a first hinge shaft, and a second hinge shaft;

[0008] Four fingers are connected to one end of the palm, the joint mechanism is located inside the palm, and one side of the joint mechanism extends out of the palm. The thumb is connected to the palm through the joint mechanism.

[0009] The palm contains a linear actuator for the thumb, which controls the joint mechanism to drive the thumb to flex and lateral movements.

[0010] The thumb includes the proximal phalanx, middle phalanx, and distal phalanx. Hinge shaft one and hinge shaft two pass through the shells at both ends of the middle phalanx and are fixedly connected to the middle phalanx respectively.

[0011] One end of the proximal phalanx is hinged to the joint mechanism, the other end of the proximal phalanx is hinged to one end of the middle phalanx via hinge axis one, and the other end of the middle phalanx is hinged to the distal phalanx via hinge axis two.

[0012] The thumb is equipped with a drive rod, a drive block, and a connecting rod; one end of the drive rod is fixedly connected to the joint mechanism, the other end of the drive rod is hinged to one end of the drive block, and the other end of the drive block is rotatably connected to the hinge shaft.

[0013] One end of the connecting rod is hinged to the inside of the shell near the phalanx, and the other end of the connecting rod is hinged to one end of the distal phalanx;

[0014] A limiting protrusion is provided on the inner wall of the middle finger joint housing, and one side of the drive block abuts against one side of the limiting protrusion.

[0015] Furthermore, the joint mechanism includes a lateral rocker block and a rotating part; the lateral rocker block has a "U"-shaped structure, one end of the lateral rocker block is rotatably connected to the inside of the palm, one end of the rotating part is located at the "U"-shaped structure and is hinged to the lateral rocker block at B, and the other end of the rotating part is fixedly connected to one end of the drive rod.

[0016] Furthermore, the shell of the proximal phalanx is hinged to the lateral rocker block at C, and the axis of the hinge axis between the proximal phalanx and the lateral rocker block is parallel to the axis of the rotation axis between the rotating part and the lateral rocker block.

[0017] Furthermore, a first spring connecting part is provided on the end face of the drive block that abuts against the limiting protrusion, and a second spring connecting part is provided on the end of the connecting rod that is hinged to the distal phalanx; a spring is provided between the first spring connecting part and the second spring connecting part.

[0018] Furthermore, the distal phalanx includes a distal phalanx skeleton and a distal phalanx rubber coating; a connecting plate is symmetrically arranged at one end of the distal phalanx skeleton, a connecting rod is hinged to the connecting plate, and the end of the connecting rod is located in the gap formed by the connecting plate; the hinge shaft passes through the connecting plate, and the distal phalanx rubber coating is fixedly sleeved on the distal phalanx skeleton.

[0019] Furthermore, a winding groove is provided at the end of the drive block that is hinged to the hinge shaft, and a wire-passing hole is provided in the middle part of the connecting rod.

[0020] Furthermore, a wire-passing hole one and a wire-passing hole two are respectively provided on the inner side wall of the proximal phalanx housing.

[0021] Furthermore, a tactile sensor is provided on the distal phalanx. The tactile sensor includes a sensor body and a wiring harness. One end of the sensor body is fixedly connected to the distal phalanx skeleton, and the other end serves as the sensing part located at the fingertip. One end of the wiring harness is electrically connected to the sensor body, and the other end passes through the thumb and extends into the palm to be electrically connected to the dexterous hand control center.

[0022] Furthermore, the thumb linear actuator is one of an electric cylinder, a pneumatic cylinder, or a hydraulic cylinder.

[0023] The beneficial effects of this application are:

[0024] 1. The thumb movement mechanism of this utility model is an anthropomorphic dexterous hand. The thumb uses a coupled linkage movement mechanism inside the thumb to achieve thumb bending. The structure is simple and easy to maintain, reducing the failure rate of the thumb movement mechanism during use. Furthermore, the layout of the thumb linear actuator is changed, and the linear actuators used to drive thumb bending are all arranged in the palm, reducing the volume of the thumb near the phalanx and improving the dexterity of the hand.

[0025] 2. The thumb movement mechanism of this invention, anthropomorphic dexterous hand, utilizes a spring. When the distal or middle phalanx of the thumb is impacted in an inward bending direction, the distal or middle phalanx will rotate around the hinge axis, causing the spring to deform. This converts the impact energy received by the distal or middle phalanx into the elastic potential energy of the spring, thereby reducing the impact force on the thumb's actuator, improving the thumb's impact resistance, and enhancing the reliability of the anthropomorphic dexterous hand's working structure.

[0026] 3. The thumb movement mechanism of this utility model for a humanoid dexterous hand changes the wiring form of the tactile sensor harness. Since the relative distance between hinge shaft one and hinge shaft two does not change when the thumb is bent, the relative displacement and bending of the harness and adjacent parts inside the thumb are avoided, ensuring the integrity of the harness sheath and reducing the impact on finger movement. Attached Figure Description

[0027] To more clearly illustrate the technical solutions in the embodiments of this utility model or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this utility model. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0028] Figure 1 This is a three-dimensional structural schematic diagram of the present invention;

[0029] Figure 2 This is a utility model Figure 1 A magnified view of a portion of point A;

[0030] Figure 3 This is a three-dimensional structural diagram of the thumb of this utility model;

[0031] Figure 4 This is a cross-sectional view of the thumb of this utility model;

[0032] Figure 5This is a three-dimensional structural diagram of the near-knuckle shell of this utility model;

[0033] Figure 6 This is a schematic diagram of the structure of the drive block of this utility model;

[0034] Figure 7 This is a schematic diagram of the connecting rod of this utility model;

[0035] Figure 8 This is a three-dimensional structural diagram of the distal phalanx skeleton of this utility model;

[0036] Figure 9 This is a schematic diagram of the structure of the present invention when the thumb is bent.

[0037] Figure label:

[0038] 1. Palm; 2. Thumb; 201. Proximal knuckle; 2011. Wire hole one; 2012. Wire hole two; 202. Middle knuckle; 2021. Limiting protrusion; 203. Distal knuckle; 2031. Distal knuckle skeleton; 20311. Connecting plate; 2032. Distal knuckle rubber coating; 3. Four fingers; 4. Joint mechanism; 401. Side swing block; 402. Rotating part; 5. Hinge shaft one; 6. Hinge shaft two; 7. Drive rod; 8. Drive block; 801. First spring connecting part; 802. Wire winding groove; 9. Connecting rod; 901. Second spring connecting part; 902. Wire winding groove; 10. Spring; 1101. Sensor body; 1102. Wire harness; B~C. Hinge points. Detailed Implementation

[0039] In the description of this utility model, it should be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "clockwise", "counterclockwise", etc., indicating the orientation or positional relationship are based on the orientation or positional relationship shown in the accompanying drawings, and are only for the convenience of describing this utility model and simplifying the description, and are not intended to indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of this utility model.

[0040] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of this utility model, "a plurality of" means two or more, unless otherwise explicitly specified.

[0041] In this utility model, unless otherwise explicitly specified and limited, the terms "installation," "connection," "linking," and "fixing," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this utility model according to the specific circumstances.

[0042] Currently, a dexterous hand is an automated operating device that can mimic certain movements and functions of the human hand to grasp, move objects, or operate tools according to a fixed program. It needs to simultaneously meet various conditions such as gripping force, gripping accuracy, self-adaptation, and degrees of freedom. In order to complete the bending and lateral swinging movements of the thumb, two linear drive mechanisms are needed to drive it separately in the dexterous hand.

[0043] In the prior art, in order to realize the bending and lateral movement of the thumb, a linear drive mechanism is directly arranged at the proximal joint of the thumb to realize the bending function of the thumb. For some humanoid dexterous hands that require large clamping force, the linear drive mechanism is relatively large. This results in a large proximal joint of the thumb. Therefore, for a single thumb, the distal joint, middle joint, and proximal joint are difficult to cooperate to clamp the object, which will interfere with the clamping action of the thumb.

[0044] Based on this, this application proposes a thumb motion mechanism for a humanoid dexterous hand. The thumb uses a coupled linkage motion mechanism inside to achieve thumb bending, which simplifies the motion mechanism, reduces the failure rate during use, and changes the layout of the thumb linear actuator so that the linear actuator used to drive thumb bending is located in the palm, reducing the volume of the thumb near the knuckle, improving the dexterity of the hand. In addition, a spring is provided to buffer the external force on the finger and avoid damage to the thumb.

[0045] To make the above-mentioned objectives, features and advantages of this application more apparent and understandable, the application will be further described in detail below with reference to the accompanying drawings and embodiments. Example

[0046] See Figure 1 The schematic diagram of the three-dimensional structure of this utility model is shown below. Figure 2 shown Figure 1 See the enlarged view of point A. Figure 3 The diagram shown illustrates the three-dimensional structure of the thumb.

[0047] This embodiment proposes a thumb movement mechanism for a humanoid dexterous hand, including: a palm 1, a joint mechanism 4, a first hinge shaft 5, and a second hinge shaft 6; one end of the palm 1 is connected to four fingers 3, the joint mechanism 4 is disposed inside the palm 1, and one side of the joint mechanism 4 extends out of the palm 1, the palm 1 is connected to the thumb 2 through the joint mechanism 4, and a thumb linear actuator is disposed inside the palm 1. Under the control of the thumb linear actuator, the joint mechanism 4 drives the thumb 2 to perform bending and lateral movements.

[0048] The joint mechanism 4 includes a side rocker block 401 and a rotating part 402. The side rocker block 401 has a "U" shaped structure. One end of the side rocker block 401 is rotatably connected to the inside of the palm 1. One end of the rotating part 402 is located at the "U" shaped structure and is hinged to the side rocker block 401 at B.

[0049] See Figure 4 The cross-sectional view of the thumb shown indicates that the thumb 2 includes a proximal phalanx 201, a middle phalanx 202, and a distal phalanx 203. Hinge shaft 1 5 and hinge shaft 2 6 pass through the housings at both ends of the middle phalanx 202 and are fixedly connected to the middle phalanx 202. One end of the proximal phalanx 201 is hinged to the joint mechanism 4. The other end of the proximal phalanx 201 is hinged to one end of the middle phalanx 202 via hinge shaft 1 5. The other end of the middle phalanx 202 is hinged to the distal phalanx 203 via hinge shaft 2 6. The proximal phalanx 201 is hinged to the lateral rocker block 401 at C. The axis of the hinge shaft between the proximal phalanx 201 and the lateral rocker block 401 is parallel to the axis of rotation of the rotating part 402 and the lateral rocker block 401.

[0050] The thumb 2 is internally provided with a drive rod 7, a drive block 8, and a connecting rod 9. One end of the drive rod 7 is fixedly connected to the joint mechanism 4, and the other end of the drive rod 7 is hinged to one end of the drive block 8. The other end of the drive block 8 is rotatably connected to the hinge shaft 5. One end of the connecting rod 9 is hinged to the inside of the shell of the proximal phalanx 201, and the other end of the connecting rod 9 is hinged to one end of the distal phalanx 203. The other end of the rotating part 402 is fixedly connected to one end of the drive rod 7.

[0051] See Figure 8 The diagram shows a three-dimensional structure of the distal phalanx skeleton. The distal phalanx 203 includes a distal phalanx skeleton 2031 and a distal phalanx rubber coating 2032. A connecting plate 20311 is symmetrically provided at one end of the distal phalanx skeleton 2031. A connecting rod 9 is hinged to the connecting plate 20311, and the end of the connecting rod 9 is located in the gap formed by the connecting plate 20311. The hinge shaft 6 passes through the connecting plate 20311. The distal phalanx rubber coating 2032 is fixedly sleeved on the distal phalanx skeleton 2031.

[0052] A limiting protrusion 2021 is also provided on the inner wall of the housing of the middle finger joint 202, and one side of the driving block 8 abuts against one side of the limiting protrusion 2021.

[0053] See Figure 6 The schematic diagram of the driving block shown is available in [reference]. Figure 7 The schematic diagram of the connecting rod shows that a first spring connecting part 801 is provided on the end face of the driving block 8 that abuts against the limiting protrusion 2021, and a second spring connecting part 901 is provided on the end of the connecting rod 9 that is hinged to the distal phalanx 203. A spring 10 is provided between the first spring connecting part 801 and the second spring connecting part 901. With the setting of the spring 10, when the distal phalanx 203 or the middle phalanx 202 of the thumb is impacted in the inward bending direction, the distal phalanx 203 or the middle phalanx 202 will rotate around the hinge axis, and the spring 10 will deform, thereby converting the impact energy of the distal phalanx 203 or the middle phalanx 202 into the elastic potential energy of the spring 10, thereby reducing the impact force on the thumb actuator, thereby improving the thumb's impact resistance and improving the reliability of the working structure of the anthropomorphic dexterous hand.

[0054] The end of the drive block 8 that is hinged to the hinge shaft 5 is provided with a winding groove 802, and the middle part of the connecting rod 9 is provided with a wire passage groove 902.

[0055] See Figure 5 The schematic diagram of the three-dimensional structure of the proximal phalanx shell is shown. The inner sidewall of the proximal phalanx 201 shell is provided with wire hole 1 2011 and wire hole 2 2012 respectively.

[0056] A tactile sensor is provided on the distal phalanx 203. The tactile sensor includes a sensor body 1101 and a wiring harness 1102. One end of the sensor body 1101 is fixedly connected to the distal phalanx skeleton 2031, and the other end is located at the fingertip as a sensing part. One end of the wiring harness 1102 is electrically connected to the sensor body 1101, and the other end passes through the thumb 2 and extends into the palm 1 to be electrically connected to the dexterous hand control center.

[0057] When installing the wiring harness 1102, the wiring harness 1102 is passed through the gap formed by the connecting plate 20311 and wrapped around the second hinge shaft 6 once. After wrapping, it passes through the wire groove 902 in the middle part of the connecting rod 9, then through the winding groove 802 on the drive block 8 and wrapped around the first hinge shaft 5 once. Finally, it passes through the first wire hole 2011 and the second wire hole 2012 on the inner wall of the proximal knuckle 201 and extends into the palm 1 to be electrically connected to the dexterous hand control center.

[0058] When the thumb is bent, the relative distance between hinge shaft 5 and hinge shaft 6 does not change, thus avoiding the relative displacement and bending of the wire harness 1102 and adjacent parts inside the thumb, ensuring the integrity of the wire harness sheath and reducing the impact on finger movement.

[0059] In one embodiment, the thumb linear actuator can be a linear drive device such as an electric cylinder, a pneumatic cylinder, or a hydraulic cylinder.

[0060] When controlling the lateral swing of the thumb 2: The thumb linear actuator inside the palm 1 controls the joint mechanism 4 to make the lateral swing block 401 rotate relative to the palm 1, that is, the joint mechanism 4 as a whole rotates relative to the palm 1, thereby driving the thumb 2, which is hinged to the joint mechanism 4, to rotate relative to the palm 1, thus realizing the lateral swing of the thumb 2.

[0061] When controlling the bending of the thumb 2: The thumb linear actuator control joint mechanism 4 set inside the palm 1 causes the rotating part 402 to rotate about the hinge point B relative to the lateral rocker block 401. As a result, the drive rod 7, which is fixedly connected to the rotating part 402, rotates. Under the combined action of the drive rod 7 and the drive block 8, the proximal phalanx 201 will rotate about the hinge point C that is hinged to the lateral rocker block 401. At the same time, the drive block 8 will also rotate relative to the hinge axis 5, thereby driving the limiting protrusion 2021 that abuts against the drive block 8 to rotate about the hinge axis 5. That is, the middle phalanx 202 rotates about the hinge axis 5. Since the proximal phalanx 201 and the middle phalanx 202 have rotated relative to each other, the position of the connecting rod 9 will change, and it will rotate about the hinge axis between the connecting rod 9 and the proximal phalanx 201. This drives the distal phalanx 203 to rotate about the hinge axis 6, thus realizing the bending of the thumb.

[0062] In summary, this application proposes a thumb motion mechanism for a humanoid dexterous hand. The thumb 2 is bent by using a coupled linkage motion mechanism inside the thumb 2. The structure is simple and easy to maintain, reducing the failure rate of the thumb 2 motion mechanism during use. Furthermore, the layout of the linear actuators of the thumb 2 is changed, with all linear actuators used to drive the bending of the thumb 2 arranged in the palm 1, reducing the volume of the proximal phalanx 201 of the thumb 2 and improving the dexterity of the hand.

[0063] The above description is merely a specific embodiment of this utility model, but the protection scope of this utility model is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in this utility model should be included within the protection scope of this utility model. Therefore, the protection scope of this utility model should be determined by the protection scope of the claims.

Claims

1. A thumb movement mechanism that mimics a human dexterous hand, characterized in that: It includes the palm (1), joint mechanism (4), hinge shaft one (5) and hinge shaft two (6); One end of the palm (1) is connected to four fingers (3), the joint mechanism (4) is located inside the palm (1), and one side of the joint mechanism (4) extends out of the palm (1). The palm (1) is connected to the thumb (2) through the joint mechanism (4). The palm (1) is equipped with a thumb linear actuator to control the joint mechanism (4) to drive the thumb (2) to bend and swing laterally; The thumb (2) includes the proximal phalanx (201), the middle phalanx (202) and the distal phalanx (203). The first hinge shaft (5) and the second hinge shaft (6) pass through the shells at both ends of the middle phalanx (202) and are fixedly connected to the middle phalanx (202) respectively. One end of the proximal phalanx (201) is hinged to the joint mechanism (4), the other end of the proximal phalanx (201) is hinged to one end of the middle phalanx (202) through hinge shaft one (5), and the other end of the middle phalanx (202) is hinged to the distal phalanx (203) through hinge shaft two (6). The thumb (2) is provided with a drive rod (7), a drive block (8), and a connecting rod (9); one end of the drive rod (7) is fixedly connected to the joint mechanism (4), the other end of the drive rod (7) is hinged to one end of the drive block (8), and the other end of the drive block (8) is rotatably connected to the hinge shaft (5); One end of the connecting rod (9) is hinged to the inside of the shell of the proximal phalanx (201), and the other end of the connecting rod (9) is hinged to one end of the distal phalanx (203); A limiting protrusion (2021) is provided on the inner wall of the housing of the middle finger joint (202), and one side of the drive block (8) abuts against one side of the limiting protrusion (2021).

2. The thumb movement mechanism of the anthropomorphic dexterous hand according to claim 1, characterized in that, The joint mechanism (4) includes a side rocker (401) and a rotating part (402); the side rocker (401) has a "U" shaped structure, one end of the side rocker (401) is rotatably connected to the inside of the palm (1), one end of the rotating part (402) is located at the "U" shaped structure and is hinged to the side rocker (401) at B, and the other end of the rotating part (402) is fixedly connected to one end of the drive rod (7).

3. The thumb movement mechanism of the anthropomorphic dexterous hand according to claim 2, characterized in that, The housing of the proximal phalanx (201) is hinged to the lateral rocker block (401) at C. The axis of the hinge shaft between the proximal phalanx (201) and the lateral rocker block (401) is parallel to the axis of the rotation shaft between the rotating part (402) and the lateral rocker block (401).

4. The thumb movement mechanism of the anthropomorphic dexterous hand according to claim 1, characterized in that, A first spring connecting part (801) is provided on the end face of the drive block (8) that abuts against the limiting protrusion (2021), and a second spring connecting part (901) is provided on the end of the connecting rod (9) that is hinged to the distal phalanx (203); a spring (10) is provided between the first spring connecting part (801) and the second spring connecting part (901).

5. The thumb movement mechanism of the anthropomorphic dexterous hand according to claim 1, characterized in that, The distal phalanx (203) includes a distal phalanx skeleton (2031) and a distal phalanx rubber coating (2032); a connecting plate (20311) is symmetrically arranged at one end of the distal phalanx skeleton (2031), a connecting rod (9) is hinged to the connecting plate (20311), and the end of the connecting rod (9) is located in the gap formed by the connecting plate (20311); the second hinge shaft (6) passes through the connecting plate (20311), and the distal phalanx rubber coating (2032) is fixedly sleeved on the distal phalanx skeleton (2031).

6. The thumb movement mechanism of the anthropomorphic dexterous hand according to claim 1, characterized in that, The drive block (8) and the hinge shaft (5) are hinged at the end with a winding groove (802), and the connecting rod (9) has a wire groove (902) in the middle part.

7. The thumb movement mechanism of the anthropomorphic dexterous hand according to claim 1, characterized in that, The inner wall of the proximal phalanx (201) housing is provided with a wire hole one (2011) and a wire hole two (2012).

8. The thumb movement mechanism of the anthropomorphic dexterous hand according to claim 1, characterized in that, A tactile sensor is provided on the distal phalanx (203). The tactile sensor includes a sensor body (1101) and a wire harness (1102). One end of the sensor body (1101) is fixedly connected to the distal phalanx skeleton (2031), and the other end is located at the fingertip as a sensing part. One end of the wire harness (1102) is electrically connected to the sensor body (1101), and the other end passes through the thumb (2) and extends into the palm (1) to be electrically connected to the dexterous hand control center.

9. The thumb movement mechanism of the anthropomorphic dexterous hand according to claim 1, characterized in that, The thumb linear actuator is one of an electric cylinder, a pneumatic cylinder, or a hydraulic cylinder.

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