Robot leg structure and waist-leg structure

Abstract

The invention discloses a robot leg structure and a waist-leg structure, and relates to the technical field of robots. The problems that according to an existing waist and leg structure, the overall control difficulty of a robot is increased, the overall movement coordination of the robot is reduced, and the conciseness and function dexterity of a mechanical structure cannot be considered at the same time are solved. The thigh braking mechanism is used for controlling the folding angle of the thigh and the shank, the bottom end of the thigh is fixedly connected with the knee joint rotating shaft, the top end of the shank is rotationally connected with the knee joint rotating shaft, and the knee joint driving motor is connected with the bottom end of the shank and can drive the shank to swing. The thigh braking mechanism is arranged on one side of the knee joint rotating shaft, in the process that the knee joint driving motor drives the shank to swing, the thigh inclines forwards and drives the knee joint rotating shaft to rotate, the thigh braking mechanism controls the forward inclination angle of the thigh, and when the shank stops swinging, the thigh braking mechanism brakes the knee joint rotating shaft so that the thigh can keep still. The method is mainly used for robot design.

Description

Technical Field

[0001] The present invention relates to the technical field of robots, and in particular to a leg structure and a waist-leg structure of a robot. Background Art

[0002] As an important symbol of a country's high-tech strength and development level, humanoid robots are being researched by all countries. Compared with bipedal humanoid robots, wheeled humanoid robots have better motion stability, lower energy consumption, faster speed and are widely used in actual industrial production. Although wheeled humanoid robot technology has achieved many breakthroughs, the waist and leg mechanism of wheeled humanoid robots, as the core mechanism of wheeled humanoid robot's motion ability, still has many problems to be solved. In order to give humanoid robots a larger operating space and a more reasonable anthropomorphic design, it is necessary to design and adopt a "folding" waist and leg mechanical structure. At present, most of the "folding" waist and leg structures are relatively complex, and each connecting rod joint is equipped with a joint motor. This not only increases the overall control difficulty of the robot, but also reduces the coordination of the robot's overall motion, and cannot take into account the simplicity of the mechanical structure and functional dexterity. Summary of the invention

[0003] In view of this, the present invention provides a robot leg structure and a waist-leg structure, which can control the folding angle of the robot leg structure and maintain the spatial posture of the robot leg structure to improve the flexibility of the robot movement.

[0004] In order to solve the above technical problems, the technical solution adopted by the present invention is:

[0005] A robot leg structure includes a thigh, a calf and a knee joint shaft, wherein the bottom end of the thigh is fixedly connected to the knee joint shaft, and the top end of the calf is rotatably connected to the knee joint shaft. The structure also includes a knee joint drive motor and a thigh brake mechanism for controlling the folding angle of the thigh and the calf. The knee joint drive motor is connected to the bottom end of the calf and can drive the calf to swing. The thigh brake mechanism is arranged on one side of the knee joint shaft. When the knee joint drive motor drives the calf to swing, the thigh leans forward and drives the knee joint shaft to rotate. The thigh brake mechanism controls the thigh forward leaning angle. When the calf stops swinging, the thigh brake mechanism stops the knee joint shaft to keep the thigh still.

[0006] Furthermore, the thigh brake mechanism includes a synchronous belt, a large pulley and a small pulley. The large pulley is coaxially installed on one side of the knee joint drive motor and is fixed. The small pulley is coaxially connected to the knee joint rotating shaft. The synchronous belt is sleeved on the large pulley and the small pulley and is tensioned.

[0007] Furthermore, the thigh brake mechanism also includes a tensioning wheel, which squeezes the synchronous belt to achieve tensioning of the synchronous belt.

[0008] Furthermore, the gear ratio between the large pulley and the small pulley is 2:1.

[0009] Furthermore, the thigh includes an upper connecting rod and an upper supporting rib. Two upper connecting rods are provided. The two upper connecting rods are arranged side by side along the axis direction of the knee joint rotation axis. The upper supporting rib is arranged between the two upper connecting rods and connects the two upper connecting rods to increase the rigidity of the thigh.

[0010] Furthermore, the calf includes a lower connecting rod and a lower supporting rib. There are two lower connecting rods, which are arranged side by side along the axis of the knee joint rotation axis. The lower supporting rib is arranged between the two lower connecting rods and connects the two lower connecting rods to increase the rigidity of the calf.

[0011] Another technical solution of the present invention is: a robot waist and leg structure, including a robot leg structure, and also including an upper limb connecting piece and a waist joint driving motor. The upper limb connecting piece is rotatably installed on the top of the thigh, and the waist joint driving motor is installed on the thigh and can drive the upper limb connecting piece to swing back and forth.

[0012] Furthermore, the thigh adopts a bending structure and bends toward the rear of the robot's leg structure. When the robot's leg structure is in an upright state, the axis of the waist joint drive motor and the axis of the knee joint drive motor are in the same vertical plane.

[0013] Compared with the prior art, the present invention has the following beneficial effects:

[0014] 1. The waist and leg structure of the robot of the present invention has two degrees of freedom, namely, squatting or standing movement of the legs and pitching movement of the waist. The robot is more flexible as a whole under these two degrees of freedom.

[0015] 2. The thigh brake mechanism of the present invention adopts a fixed synchronous belt transmission structure, through which not only the folding angle between the thigh and the calf can be controlled to adapt to different working conditions, but also the torque of the robot's legs and upper limbs can be passively carried. There is no need to install an additional joint motor at the knee joint for torque control, which not only reduces the control difficulty of the waist and leg structure, but also reduces the overall weight of the mechanism.

[0016] 3. The thigh of the present invention adopts a bending design and bends toward the rear of the robot. When the leg of the robot is in an upright state, the bottom end of the thigh deflects backward, so that the upper end of the thigh tilts forward. In this way, when the waist joint drive motor is installed to the top of the thigh, the axis of the waist joint drive motor can be in the same vertical plane as the axis of the knee joint drive motor. At the same time, when the leg is squatting, although the leg is bent and folded backward as a whole, the axis of the waist joint drive motor and the axis of the knee joint drive motor can always be in the same vertical plane due to the forward tilt of the thigh. That is, the mass distribution of the waist and leg structure of the robot is concentrated. Whether it is in an upright state or a folded state, the main mass is always distributed on the vertical plane where the axis of the waist joint drive motor and the axis of the knee joint drive motor are located, and coincides with the gravity direction of the robot trunk. This can ensure that the waist and leg structure of the humanoid robot is more stable as a whole during squatting or standing. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] The accompanying drawings are incorporated as part of this application and are used to provide a further understanding of the present invention.

[0018] Figure 1 The figure is a schematic diagram of the three-dimensional structure of a robot leg structure of the present invention.

[0019] Figure 2 It is a schematic diagram of the three-dimensional structure of the robot waist and leg structure of the present invention.

[0020] Figure 3 It is a side view of the robot waist and leg structure of the present invention.

[0021] Figure 4 It is a cross-sectional view of the robot waist and leg structure of the present invention.

[0022] Figure 5 It is a three-dimensional schematic diagram of the waist and leg structure of the robot of the present invention in a folded state.

[0023] Figure 6 It is a side view of the robot waist and leg structure of the present invention in a folded state.

[0024] Figure 7 It is a schematic diagram of the relative position relationship between the small pulley and the synchronous belt when the small pulley swings with the calf.

[0025] Explanation of the reference numerals: 1-knee joint pivot; 2-thigh; 21-upper connecting rod; 22-upper supporting rib; 3-calf; 31-lower connecting rod; 32-lower supporting rib; 4-base; 5-knee joint drive motor; 6-thigh brake mechanism; 61-pulley bracket; 62-synchronous belt; 63-large pulley; 64-small pulley; 65-tensioning pulley; 7-upper limb connecting piece; 8-lumbar joint drive motor. DETAILED DESCRIPTION

[0026] The present invention is described in detail below with reference to the accompanying drawings and specific embodiments.

[0027] Figure 1 FIG. 4 shows a schematic diagram of a robot leg structure of the present invention, as shown in FIG. Figure 1 As shown, the robot leg structure of this embodiment includes a knee joint shaft 1, a thigh 2, a shank 3, a base 4 and a knee joint drive motor 5. The thigh 2 and the shank 3 are connected in series via the knee joint shaft 1, the bottom end of the thigh 2 is fixedly connected to the knee joint shaft 1, and the top end of the shank 3 is rotatably connected to the knee joint shaft 1, so as to achieve the bending of the leg at the knee joint. Figure 1 As shown, the thigh 2 is composed of an upper connecting rod 21 and an upper supporting rib 22. Two upper connecting rods 21 are provided. The two upper connecting rods 21 are arranged side by side along the axis direction of the knee joint shaft 1. The upper supporting rib 22 is arranged between the two upper connecting rods 21 and connects the two upper connecting rods 21 to increase the rigidity of the thigh 2. The bottom end of the upper connecting rod 21 is fixedly connected to the knee joint shaft 1. Figure 1 As shown, the shank 3 is composed of a lower connecting rod 31 and a lower supporting rib 32. Two lower connecting rods 31 are provided. The two lower connecting rods 31 are arranged side by side along the axis direction of the knee joint shaft 1. The lower supporting rib 32 is arranged between the two lower connecting rods 31 and connects the two lower connecting rods 31 to increase the rigidity of the shank 3. The top ends of the two lower connecting rods 31 are connected to the knee joint shaft 1 via bearings. The base 4 is used to connect the wheeled mobile platform of the wheeled robot. Two knee joint drive motors 5 are provided. The two knee joint drive motors 5 are coaxially arranged on the base 4 and arranged in parallel below the knee joint shaft 1. Each lower connecting rod 31 corresponds to a knee joint drive motor 5. The bottom end of the lower connecting rod 31 is connected to the motor shaft of the corresponding knee joint drive motor 5 and can rotate with the motor shaft. The leg structure of this embodiment can realize the backward swing of the calf 3 and the forward tilt of the thigh 2 under the coordinated cooperation of the thigh 2, the calf 3, the knee joint shaft 1 and the knee joint drive motor 5. The leg structure can realize the squatting of the robot leg under the joint movement of the two. Specifically, when the whole leg is in an upright state, such as Figure 1 In the state shown, the knee joint drive motor 5 drives the calf 3 and the knee joint shaft 1 to swing backwards. At this time, the bottom end of the thigh 2 is driven backwards. Since the thigh 2 is rotationally connected to the calf 3 via the knee joint shaft 1, the thigh 2 can tilt forward under its own gravity and the load above (in this process, the calf 3 and the knee joint shaft 1 can be regarded as a sweeping leg, and the bottom end of the thigh 2 is driven backwards, so that the thigh 2 tilts forward as a whole). A horizontal fold occurs between the thigh 2 and the calf 3, so that the robot as a whole presents a squatting posture, that is, Figure 5 and Figure 6The posture shown. In this embodiment, the knee joint drive motor 5 is placed downward, which, on the one hand, reduces the load at the knee joint and realizes a lightweight design of the leg; on the other hand, it reduces the volume and redundancy at the knee joint, and the leg design is more concise, which is conducive to the folding of the leg and increases the flexibility of the knee joint movement. At the same time, the forward tilt of the thigh 2 depends on its own gravity and the load above, so the forward tilt of the thigh 2 is passively driven, and there is no need to set up a separate driving component to realize the forward tilting action, which further simplifies the leg structure of the robot and makes the overall structure more concise.

[0028] Since the forward tilt of the thigh 2 is achieved by its own gravity and the load above, the thigh 2 is completely folded with the calf 3 after tilting forward, and cannot be maintained in a squatting posture of different degrees. Therefore, the leg structure of this embodiment also includes a thigh brake mechanism 6 for controlling the folding angle of the thigh 2 and the calf 3, such as Figure 1 As shown, there are two thigh brake mechanisms 6, which are arranged side by side between the two lower connecting rods 31 of the calf 3. The thigh brake mechanism 6 is installed on the base 4 and connected to the knee joint shaft 1. When the calf 3 drives the knee joint shaft 1 to swing backward, due to the forward tilt of the thigh 2, the thigh 2 drives the knee joint shaft 1 to rotate, and the thigh brake mechanism 6 can control the forward tilt angle of the thigh. When the calf 3 stops swinging, the thigh brake mechanism 6 brakes the knee joint shaft 1 to keep the thigh 2 motionless. At this time, the robot leg structure remains motionless in the squatting state, thereby maintaining the spatial posture of the humanoid robot, that is, the robot leg structure of this embodiment can control the squatting height of the leg through the thigh brake mechanism 6, thereby improving the flexibility of the robot leg movement.

[0029] Combination Figure 1 The thigh brake mechanism 6 of this embodiment includes a pulley bracket 61, a synchronous belt 62, a large pulley 63, a small pulley 64 and a tensioning pulley 65. The large pulley 63 is fixed to the base 4 via the pulley bracket 61. The large pulley 63 is coaxially arranged with the motor shaft of the knee joint drive motor 5. The small pulley 64 is coaxially connected to the knee joint shaft 1. The synchronous belt 62 is sleeved on the large pulley 63 and the small pulley 64. The tensioning pulley 65 is installed on the lower support rib 32. The tensioning pulley 65 squeezes and tensions the synchronous belt 62. The large pulley 63 of this embodiment controls the rotation angle of the small pulley 64 through the synchronous belt 62, thereby controlling the rotation angle of the thigh 2 relative to the calf 3. Specifically, as Figure 7As shown in FIG. 1 , it is a schematic diagram of the relative position relationship between the small pulley and the synchronous belt when the small pulley swings with the calf. Since the large pulley 63 is fixed, the large pulley 63 acts as a brake on the synchronous belt 62, which can prevent the synchronous belt 62 from rotating in the circumferential direction. When the calf 3 drives the knee joint shaft 1 and the small pulley 64 to revolve clockwise around the large pulley 63 (the problem of the thigh 2 tilting forward to drive the small pulley 64 to rotate is not considered at this time), a relative movement occurs between the small pulley 64 and the synchronous belt 62 ( Figure 7 The black dot a in the middle shows the motion relationship between the synchronous belt 62 and the small pulley 64. The small pulley 64 is driven by the synchronous belt 62 to rotate counterclockwise. The rotation angle of the small pulley 64 is restricted by the synchronous belt 62, so the design of the large pulley 63 and the synchronous belt 62 can limit the rotation angle of the small pulley 64. Although the small pulley 64 can also be driven by the knee joint shaft 1 to rotate counterclockwise during the forward tilt of the thigh 2, the rotation angle of the small pulley 64 will not change under the restriction of the large pulley 63 and the synchronous belt 62, that is, the forward tilt of the thigh 2 will not affect the counterclockwise rotation angle of the small pulley 64. At the same time, the large pulley 63 and the synchronous belt 62 will also limit the forward tilt angle of the thigh 2 through the small pulley 64. When the small pulley 64 stops revolving with the calf 3, the small pulley 64 is braked by the synchronous belt 62 and the large pulley 63 and no longer rotates counterclockwise, thereby achieving the braking of the knee joint shaft 1. At this time, although the knee joint shaft 1 stops rotating, the thigh 2 still has a tendency to tilt forward under its own gravity and the load of the upper limbs. The torque is transmitted to the synchronous belt 62 and the large pulley 63 via the knee joint shaft 1 and the small pulley 64 and is carried by the synchronous belt 62 and the large pulley 63. In other words, in this embodiment, the torque of the thigh 2 and the upper limb of the robot is carried by the synchronous belt 62 and the large pulley 63 and the spatial posture of the leg structure of the humanoid robot is maintained.

[0030] It should be noted that the angle of rotation of the thigh 2 relative to the shank 3 in this embodiment is the same as the angle ratio β of the rotation of the shank 3 and the gear ratio of the large and small pulleys, that is, when the gear ratio of the large and small pulleys is 2:1, β=2:1. The reason is that when the shank 3 rotates clockwise around the axis of the knee joint drive motor 5 (the axis of the large pulley 63) by an angle θ, the angle of rotation of the shank 3 relative to the large pulley 63 is θ, and vice versa, the angle of rotation of the large pulley 63 relative to the shank 3 is θ, and when the gear ratio of the large and small pulleys 64 is 2:1, the angle of rotation of the small pulley 64 relative to the large pulley 63 is 2θ, then the angle of rotation of the thigh 2 relative to the shank 3 is also 2θ, so the angle of rotation of the thigh 2 relative to the shank 3 and the angle ratio of the rotation of the shank 3 are 2:1. With such a design, the relative rotation angle of the thigh 2 and the shank 3 or the folding angle between the two can be controlled by designing the gear ratio of the large and small pulleys 64.

[0031] Figures 2 to 6 FIG. 4 shows a schematic diagram of a robot waist and leg structure of the present invention. Figures 2 to 6 As shown, the robot waist and leg structure of this embodiment includes the robot leg structure as described above, and also includes an upper limb connection piece 7 and a waist joint drive motor 8. The top of the upper connecting rod 21 is connected to the upper limb connection piece 7 through a bearing. The waist joint drive motor 8 is provided with two, and the two waist joint drive motors 8 are symmetrically arranged on both sides of the two upper connecting rods 21. The waist joint drive motor 8 is installed on the upper connecting rod 21 and can drive the upper limb connection piece 7 to swing back and forth. The upper limb connection piece 7 can be used to connect the upper limb of the robot. When the knee joint drive motor 5 drives the leg to squat, the upper limb connection piece 7 tilts forward with the thigh 2, causing the robot's upper limb to tilt forward, and the waist joint drive motor 8 drives the upper limb connection piece 7 to rotate in the opposite direction to compensate for the angle of the robot's upper limb tilting forward, so that the robot's upper limb is always in an upright state. That is, when the robot is squatting or standing up, the waist joint drive motor 8 rotates in conjunction with the knee joint drive motor 5 to keep the spatial pitch angle of the robot's upper limb unchanged. After the robot squats or stands up, the waist joint drive motor 8 can drive the robot's upper limb to achieve a pitching action.

[0032] like Figure 3 As shown, the upper connecting rod 21 of the thigh 2 of this embodiment adopts a bending rod, and is bent toward the rear of the robot. When the leg of the robot is in an upright state, the bottom end of the thigh 2 deflects backward, so that the upper end of the thigh 2 tilts forward, so that when the waist joint drive motor 8 is installed to the top of the thigh 2, the axis of the waist joint drive motor 8 can be in the same vertical plane as the axis of the knee joint drive motor 5. At the same time, when the leg is squatting, although the leg is bent backward as a whole, the axis of the waist joint drive motor 8 and the axis of the knee joint drive motor 5 can always be in the same vertical plane due to the forward tilt of the thigh 2. That is, the mass distribution of the waist and leg structure of the robot is concentrated. Whether it is in an upright state or a folded state, the main mass is always distributed on the vertical plane where the axis of the waist joint drive motor 8 and the axis of the knee joint drive motor 5 are located, and coincides with the gravity direction of the robot trunk, which can ensure that the waist and leg structure is more stable as a whole in the process of squatting or standing upright.

[0033] It can be seen that the waist and leg structure of the robot in this embodiment has two degrees of freedom, namely the squatting or upright movement of the legs and the pitching movement of the waist. The robot is more flexible as a whole under these two degrees of freedom. At the same time, the thigh brake mechanism 6 of this embodiment adopts a fixed synchronous belt transmission structure, through which not only the folding angle between the thigh 2 and the calf 3 can be controlled to adapt to different working conditions, but also the torque of the robot's legs and upper limbs can be passively carried, without the need to install additional joint motors at the knee joints for torque control, which not only reduces the control difficulty of the waist and leg structure, but also reduces the weight of the entire mechanism. This embodiment also performs topological optimization on the main load-bearing parts, and reduces the weight of the mechanism while ensuring that the overall strength and stiffness of the mechanical structure meet the requirements, thereby reducing the joint drive and load-bearing torque and reducing energy consumption.

[0034] Combine the following Figure 2 and Figure 5 The working process of the robot waist and leg structure of the present invention is described in detail.

[0035] When the waist and leg structure of the entire robot is in an upright state, Figure 2 In the state shown, the knee joint drive motor 5 drives the calf 3 and the knee joint shaft 1 to swing backward, the bottom end of the thigh 2 is driven backward, the thigh 2 is tilted forward due to its own gravity and the load above, and the thigh 2 and the calf 3 are horizontally folded, so that the robot as a whole presents a squatting posture, that is, Figure 5 The posture shown. During this process, the waist joint drive motor 8 drives the upper limb connecting piece 7 to rotate in the opposite direction to compensate for the forward tilt angle of the robot's upper limbs, so that the robot's upper limbs are always in an upright state. When the knee joint drive motor 5 stops driving, the calf 3 no longer swings, and the small pulley 64 stops revolving with the calf 3. The small pulley 64 is braked by the synchronous belt 62 and the large pulley 63 and no longer rotates counterclockwise, achieving the braking of the knee joint shaft 1. At this time, the thigh 2 no longer tilts forward, and the robot's leg structure remains motionless in the squatting state. The synchronous belt 62 and the large pulley 63 carry the torque of the thigh 2 and the robot's upper limbs and maintain the spatial posture of the humanoid robot's leg structure.

[0036] Finally, it should be noted that the above embodiments are only used to illustrate the technical solution of the present invention, rather than to limit the scope of protection of the present invention. Although the present invention has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that the technical solution of the present invention can be modified or replaced by equivalents without departing from the essence and scope of the technical solution of the present invention.

Claims

1. A robot leg structure, comprising a thigh, a calf and a knee joint shaft, wherein the bottom end of the thigh is fixedly connected to the knee joint shaft, and the top end of the calf is rotatably connected to the knee joint shaft, characterized in that: It also includes a knee joint drive motor and a thigh brake mechanism for controlling the folding angle of the thigh and the calf. The knee joint drive motor is connected to the bottom end of the calf and can drive the calf to swing. The thigh brake mechanism is arranged on one side of the knee joint shaft. When the knee joint drive motor drives the calf to swing, the thigh leans forward and drives the knee joint shaft to rotate. The thigh brake mechanism controls the forward leaning angle of the thigh. When the calf stops swinging, the thigh brake mechanism stops the knee joint shaft to keep the thigh still.

2. A robot leg structure according to claim 1, characterized in that: The thigh brake mechanism includes a synchronous belt, a large pulley and a small pulley. The large pulley is coaxially installed on one side of the knee joint drive motor and is fixed. The small pulley is coaxially connected to the knee joint shaft. The synchronous belt is sleeved on the large pulley and the small pulley and is tensioned.

3. A robot leg structure according to claim 2, characterized in that: The thigh brake mechanism also includes a tensioning wheel, which squeezes the synchronous belt to achieve tensioning of the synchronous belt.

4. A robot leg structure according to claim 2, characterized in that: The gear ratio between the large pulley and the small pulley is 2:

1.

5. The robot leg structure according to claim 1, characterized in that: The thigh includes an upper connecting rod and an upper supporting rib. Two upper connecting rods are provided. The two upper connecting rods are arranged side by side along the axis direction of the knee joint rotation axis. The upper supporting rib is arranged between the two upper connecting rods and connects the two upper connecting rods to increase the rigidity of the thigh.

6. The robot leg structure according to claim 1, characterized in that: The calf includes a lower connecting rod and a lower supporting rib plate. Two lower connecting rods are provided. The two lower connecting rods are arranged side by side along the axis direction of the knee joint rotation axis. The lower supporting rib plate is arranged between the two lower connecting rods and connects the two lower connecting rods to increase the rigidity of the calf.

7. A robot waist and leg structure, characterized in that: It comprises a robot leg structure as described in any one of claims 1 to 6, and also comprises an upper limb connecting piece and a waist joint driving motor, wherein the upper limb connecting piece is rotatably mounted on the top of the thigh, and the waist joint driving motor is mounted on the thigh and can drive the upper limb connecting piece to swing back and forth.

8. The robot waist and leg structure according to claim 7, characterized in that: The thigh adopts a bent structure and is bent toward the rear of the robot leg structure. When the robot leg structure is in an upright state, the axis of the waist joint drive motor and the axis of the knee joint drive motor are in the same vertical plane.

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