A robot leg structure and waist-leg structure

Abstract

The application discloses a robot leg structure and waist-leg structure and relates to the technical field of robots. The existing waist-leg structure not only increases the control difficulty of the whole robot, but also reduces the coordination of the whole robot movement, and cannot consider the simplicity and function agility of the mechanical structure. The application comprises a thigh, a shank, a knee joint rotating shaft, a knee joint driving motor and a thigh brake mechanism 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 rotatably connected with the knee joint rotating shaft, the knee joint driving motor is connected with the bottom end of the shank and can drive the shank to swing, and the thigh brake mechanism is arranged on one side of the knee joint rotating shaft. During the driving of the shank to swing by the knee joint driving motor, the thigh inclines forward and drives the knee joint rotating shaft to rotate, the thigh brake mechanism controls the inclination angle of the thigh, and when the shank stops swinging, the thigh brake mechanism stops the knee joint rotating shaft, so that the thigh remains stationary. The application is mainly used for robot design.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of robot technology, and in particular to a robot leg structure and a waist-leg structure. BACKGROUND

[0002] As an important symbol of a country's high-tech strength and development level, countries are sparing no effort to invest in humanoid robot technology. Compared with biped 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 made many breakthroughs, there are still many problems to be solved in the waist-leg mechanism of wheeled humanoid robots, which is the core mechanism of the motion ability of wheeled humanoid robots. In order to make the humanoid robot have a larger operating space and a more reasonable anthropomorphic design, it is necessary to design a "folding" waist-leg mechanical structure. Most of the current "folding" waist-leg structures are relatively complex, and each link joint is provided with a joint motor. This not only increases the overall control difficulty of the robot, but also reduces the overall motion coordination of the robot, and cannot balance the simplicity and functional flexibility of the mechanical structure. SUMMARY

[0003] Therefore, the present application 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, so as to improve the flexibility of the robot motion.

[0004] To solve the above technical problems, the technical scheme adopted by the present application is as follows:

[0005] A robot leg structure, comprising a thigh, a calf and a knee joint shaft, the bottom end of the thigh being fixedly connected with the knee joint shaft, the top end of the calf being rotatably connected with the knee joint shaft, further comprising a knee joint driving motor and a thigh brake mechanism for controlling the folding angle of the thigh and the calf, the knee joint driving motor being connected with the bottom end of the calf and being capable of driving the calf to swing, the thigh brake mechanism being arranged on one side of the knee joint shaft, during the process of driving the calf to swing by the knee joint driving motor, the thigh is inclined forward and drives the knee joint shaft to rotate, the thigh brake mechanism controls the inclination angle of the thigh, and when the calf stops swinging, the thigh brake mechanism stops the knee joint shaft to make the thigh keep still.

[0006] Further, the thigh brake mechanism comprises a synchronous belt, a large pulley and a small pulley, the large pulley is coaxially installed on one side of the knee joint driving motor and is fixedly not movable, the small pulley is coaxially connected with the knee joint shaft, and the synchronous belt is sleeved on the large pulley and the small pulley and is tensioned.

[0007] Further, the thigh brake mechanism further comprises a tension pulley, the tension pulley presses the synchronous belt to realize the tensioning of the synchronous belt.

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

[0009] Further, the thigh includes upper links and an upper support rib plate, the two upper links are arranged side by side along the direction of the axis of the knee joint pivot, and the upper support rib plate is arranged between and connected to the two upper links to increase the rigidity of the thigh.

[0010] Further, the lower leg includes lower links and a lower support rib plate, the two lower links are arranged side by side along the direction of the axis of the knee joint pivot, and the lower support rib plate is arranged between and connected to the two lower links to increase the rigidity of the lower leg.

[0011] Another technical solution of the present application is a robot waist-leg structure, which comprises a robot leg structure, an upper limb connecting piece and a waist joint driving motor, the upper limb connecting piece is rotatably installed at the top end of the thigh, and the waist joint driving motor is installed on the thigh and can drive the upper limb connecting piece to swing forward and backward.

[0012] Further, the thigh adopts a bending structure and bends towards the back of the robot leg structure, and when the robot leg structure is in an upright state, the axis of the waist joint driving motor and the axis of the knee joint driving motor are in the same vertical plane.

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

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

[0015] 2. The thigh brake mechanism of the present application adopts a fixed synchronous belt transmission structure, which can not only control the folding angle between the thigh and the lower leg to adapt to different working conditions, but also passively bear the torque of the robot leg and the upper limb, without the need for additional joint motors at the knee joint for torque control, thereby reducing the control difficulty of the waist-leg structure and reducing the overall weight of the mechanism.

[0016] 3、the thigh of the application adopts a bending design, and bends towards the rear of the robot, when the leg of the robot is in an upright state, the bottom end of the thigh deflects rearward, so that the upper end of the thigh inclines forward, so that when the waist joint driving motor is installed to the top end of the thigh, the axis of the waist joint driving motor can be in the same vertical plane as the axis of the knee joint driving motor, and when the leg is crouching, although the leg as a whole bends and folds rearward, the axis of the waist joint driving motor and the axis of the knee joint driving motor can always be in the same vertical plane due to the forward inclination of the thigh. That is, the waist-leg structure of the robot has concentrated mass distribution, whether in the upright state or the folded state, the main mass is always distributed on the vertical plane where the axis of the waist joint driving motor and the axis of the knee joint driving motor are located, and coincides with the direction of the gravity of the robot trunk, which can ensure that the waist-leg structure is more stable during crouching or standing. BRIEF DESCRIPTION OF DRAWINGS

[0017] The accompanying drawings are included as part of the disclosure to provide a further understanding of the application.

[0018] Figure 1 It is a three-dimensional structure schematic view of a robot leg structure of the application.

[0019] Figure 2 It is a three-dimensional structure schematic view of a robot waist-leg structure of the application.

[0020] Figure 3 It is a side view of a robot waist-leg structure of the application.

[0021] Figure 4 It is a sectional view of a robot waist-leg structure of the application.

[0022] Figure 5 It is a three-dimensional schematic view of a robot waist-leg structure in a folded state of the application.

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

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

[0025] Marked: 1-knee joint rotation shaft; 2-thigh; 21-upper connecting rod; 22-upper support rib plate; 3-lower leg; 31-lower connecting rod; 32-lower support rib plate; 4-base; 5-knee joint driving motor; 6-thigh brake mechanism; 61-pulley support; 62-synchronous belt; 63-large pulley; 64-small pulley; 65-tension pulley; 7-upper limb connecting piece; 8-waist joint driving motor. DETAILED DESCRIPTION

[0026] The application will be described in detail below in conjunction with the accompanying drawings and specific embodiments.

[0027] Figure 1 A structural schematic diagram of a robot leg structure of the present application is shown in the figure, Figure 1 The robot leg structure of the embodiment comprises a knee joint rotation shaft 1, a thigh 2, a shank 3, a base 4 and knee joint driving motors 5. The thigh 2 and the shank 3 are connected in series via the knee joint rotation shaft 1, the bottom end of the thigh 2 is fixedly connected to the knee joint rotation shaft 1, and the top end of the shank 3 is rotationally connected to the knee joint rotation shaft 1, so as to realize the bending of the leg at the knee joint. Figure 1 As shown in the figure, the thigh 2 is composed of upper connecting rods 21 and an upper support rib plate 22, two upper connecting rods 21 are arranged side by side along the direction of the axis of the knee joint rotation shaft 1, the upper support rib plate 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, and the bottom end of the upper connecting rod 21 is fixedly connected to the knee joint rotation shaft 1. Figure 1 As shown in the figure, the shank 3 is composed of lower connecting rods 31 and a lower support rib plate 32, two lower connecting rods 31 are arranged side by side along the direction of the axis of the knee joint rotation shaft 1, the lower support rib plate 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, and the top end of the two lower connecting rods 31 is connected to the knee joint rotation shaft 1 via a bearing. The base 4 is used to connect the wheeled mobile platform of the wheeled robot, and two knee joint driving motors 5 are arranged coaxially and oppositely on the base 4 below the knee joint rotation shaft 1, and each lower connecting rod 31 corresponds to one knee joint driving motor 5, and the bottom end of the lower connecting rod 31 is connected to the motor shaft of the corresponding knee joint driving motor 5 and can rotate with the motor shaft. The leg structure of the embodiment can realize the backward swing of the shank 3 and the forward inclination of the thigh 2 under the cooperation of the thigh 2, the shank 3, the knee joint rotation shaft 1 and the knee joint driving motors 5, and the leg structure can realize the squatting of the robot leg under the combined movement of the two. Specifically, when the entire leg is in an upright state, as shown in the figure, the knee joint driving motors 5 drive the shank 3 and the knee joint rotation shaft 1 to swing backward, at this time, the bottom end of the thigh 2 is subjected to a backward driving force, and since the thigh 2 is rotationally connected to the shank 3 via the knee joint rotation shaft 1, the thigh 2 can incline forward under its own gravity and the load above (in this process, the shank 3 and the knee joint rotation shaft 1 can be regarded as a sweeping leg, the bottom end of the thigh 2 is subjected to a backward driving force, so that the thigh 2 as a whole inclines forward), and the thigh 2 and the shank 3 are horizontally folded, so that the robot as a whole presents a squatting posture, that is, Figure 1 and Figure 5 and Figure 6The embodiment places the knee joint driving motor 5 below, which reduces the load at the knee joint, realizes lightweight design of the leg, reduces the volume and redundancy of the knee joint, and makes the leg design more simple, which is beneficial to folding of the leg and increases flexibility of the knee joint movement. Meanwhile, the forward inclination of the thigh 2 is realized by its own gravity and the load above, so the forward inclination of the thigh 2 is passive driving, and no separate driving component is needed to realize the forward inclination, which further simplifies the leg structure of the robot and makes the overall structure more simple.

[0028] Since the forward inclination of the thigh 2 is realized by its own gravity and the load above, the thigh 2 is fully folded with the lower leg 3 after the forward inclination, and cannot be kept in the posture of squatting at different degrees, so the leg structure of the embodiment further includes a thigh brake mechanism 6 for controlling the folding angle of the thigh 2 and the lower leg 3, as shown in Figure 1 The thigh brake mechanism 6 is provided with two, which are arranged side by side between the two lower connecting rods 31 of the lower leg 3, and is installed on the base 4 and connected to the knee joint rotating shaft 1. During the process that the lower leg 3 drives the knee joint rotating shaft 1 to swing backward, the thigh 2 drives the knee joint rotating shaft 1 to rotate due to the forward inclination of the thigh 2, and the thigh brake mechanism 6 can control the angle of the forward inclination of the thigh 2. When the lower leg 3 stops swinging, the thigh brake mechanism 6 stops the knee joint rotating shaft 1, so that the thigh 2 remains stationary. At this time, the leg structure of the robot remains stationary in the squatting state, so as to keep the spatial posture of the humanoid robot. That is, the leg structure of the robot of the embodiment can control the height of the squatting of the leg through the thigh brake mechanism 6, so as to improve the flexibility of the leg movement of the robot.

[0029] In combination with Figure 1 The thigh brake mechanism 6 of the embodiment includes a pulley bracket 61, a synchronous belt 62, a large pulley 63, a small pulley 64 and a tension pulley 65. The large pulley 63 is fixed to the base 4 through the pulley bracket 61, and is coaxially arranged with the motor shaft of the knee joint driving motor 5. The small pulley 64 is coaxially connected to the knee joint rotating shaft 1. The synchronous belt 62 is sleeved on the large pulley 63 and the small pulley 64. The tension pulley 65 is installed on the lower support rib plate 32 and presses and tensions the synchronous belt 62. The large pulley 63 of the embodiment controls the angle of the self-rotation of the small pulley 64 through the synchronous belt 62, so as to control the angle of the rotation of the thigh 2 relative to the lower leg 3. Specifically, as shown in Figure 7The diagram shows the relative positional relationship between the small pulley and the synchronous belt when the lower leg swings. Since the large pulley 63 is fixed, it acts as a brake on the synchronous belt 62, preventing it from rotating in a circular direction. During the clockwise revolution of the knee joint pivot 1 and the small pulley 64 around the large pulley 63 driven by the lower leg 3 (ignoring the issue of the thigh 2 tilting forward and causing the small pulley 64 to rotate), relative motion occurs between the small pulley 64 and the synchronous belt 62. Figure 7 (The black dot 'a' in the middle illustrates the kinematic relationship between the synchronous belt 62 and the small pulley 64.) The small pulley 64 rotates counterclockwise driven by the synchronous belt 62, and the angle of rotation of the small pulley 64 is constrained by the synchronous belt 62. Therefore, the design of the large pulley 63 and the synchronous belt 62 can limit the angle of rotation of the small pulley 64. Although the thigh 2 can also drive the small pulley 64 to rotate counterclockwise during the forward tilting process through the knee joint pivot 1, the angle of rotation of the small pulley 64 will not change under the constraint of the large pulley 63 and the synchronous belt 62. That is, the forward tilting of the thigh 2 will not affect the angle of counterclockwise rotation of the small pulley 64. At the same time, the large pulley 63 and the synchronous belt 62 will also limit the angle of forward tilting of the thigh 2 through the small pulley 64. When the small pulley 64 stops revolving with the lower leg 3, the small pulley 64 stops rotating counterclockwise due to the braking of the synchronous belt 62 and the large pulley 63, thereby achieving the braking of the knee joint pivot 1. At this point, although the knee joint pivot 1 has stopped rotating, the thigh 2 still tends to lean forward under its own weight and the load of the upper limb. This torque is transmitted through the knee joint pivot 1 and the small pulley 64 to the synchronous belt 62 and the large pulley 63, and is borne by the synchronous belt 62 and the large pulley 63. In other words, in this embodiment, the torque of the thigh 2 and the robot's upper limb is borne by the synchronous belt 62 and the large pulley 63, thus maintaining the spatial posture of the humanoid robot's leg structure.

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

[0031] Figures 2 to 6 A schematic diagram of a robot waist and leg structure according to the present invention is shown, as follows.Figures 2 to 6 As shown, the robot's waist and leg structure in this embodiment includes the robot leg structure as described above, as well as an upper limb connector 7 and a waist joint drive motor 8. The top end of the upper connecting rod 21 is connected to the upper limb connector 7 via a bearing. Two waist joint drive motors 8 are provided, symmetrically arranged on both sides of the two upper connecting rods 21. The waist joint drive motors 8 are mounted on the upper connecting rods 21 and can drive the upper limb connector 7 to swing back and forth. The upper limb connector 7 can be used to connect the robot's upper limb. When the knee joint drive motor 5 drives the leg to squat, the upper limb connector 7 tilts forward with the thigh 2, causing the robot's upper limb to tilt forward. The waist joint drive motor 8 drives the upper limb connector 7 to rotate in the opposite direction to compensate for the angle of the robot's upper limb tilt, so that the robot's upper limb is always in an upright state. That is, during the robot's squatting or standing process, the waist joint drive motor 8 simultaneously cooperates with the knee joint drive motor 5 to rotate, so as to keep the spatial pitch angle of the robot's upper limb unchanged. After the robot's squatting or standing action is completed, the waist joint drive motor 8 can drive the robot's upper limb to achieve pitch action.

[0032] like Figure 3 As shown, in this embodiment, the upper connecting rod 21 of the thigh 2 is a bent rod that bends towards the rear of the robot. When the robot's legs are in an upright position, the bottom end of the thigh 2 deflects backward, causing the upper end of the thigh 2 to tilt forward. This ensures that when the waist joint drive motor 8 is installed at the top of the thigh 2, the axis of the waist joint drive motor 8 is in the same vertical plane as the axis of the knee joint drive motor 5. Furthermore, when the legs squat, although the entire leg bends and folds backward, the forward tilt of the thigh 2 ensures that the axis of the waist joint drive motor 8 and the axis of the knee joint drive motor 5 remain in the same vertical plane. In other words, the mass distribution of the robot's waist and leg structure is concentrated. Whether in an upright or folded state, the main mass is always distributed in the vertical plane containing the axes of the waist joint drive motor 8 and the knee joint drive motor 5, coinciding with the direction of the robot's torso's gravity. This ensures greater stability of the humanoid robot during squatting or standing.

[0033] Therefore, the robot waist and leg structure of the embodiment has two degrees of freedom, respectively, the squatting or standing motion of the leg and the pitching motion of the waist, and the robot is more flexible as a whole under the two degrees of freedom. Meanwhile, the thigh brake mechanism 6 of the embodiment adopts a fixed synchronous belt transmission structure, through which the folding angle between the thigh 2 and the lower leg 3 can be controlled to adapt to different working conditions, and the torque of the robot leg and upper limb can be passively borne, without the need of additionally installing a joint motor at the knee joint for torque control, thereby reducing the control difficulty of the waist and leg structure and reducing the overall weight of the mechanism. The main bearing parts of the embodiment are also subjected to topological optimization processing, under the premise that the overall strength and rigidity of the mechanical structure meet the requirements, the weight of the mechanism is reduced, thereby reducing the joint driving and bearing torque and reducing the energy consumption.

[0034] The working process of the robot waist and leg structure of the embodiment will be described in detail below. Figure 2 and Figure 5 The working process of the robot waist and leg structure of the embodiment will be described in detail below.

[0035] When the waist and leg structure of the whole robot is in a standing state, as shown in the state of Figure 2 , the knee joint driving motor 5 drives the lower leg 3 and the knee joint rotating shaft 1 to swing backward, the bottom end of the thigh 2 is subjected to a driving force backward, the thigh 2 is inclined forward due to its own gravity and the load above, the horizontal folding between the thigh 2 and the lower leg 3 occurs, so that the whole robot presents a squatting posture, i.e. the posture of Figure 5 . In this process, the waist joint driving motor 8 drives the upper limb connecting piece 7 to rotate reversely to compensate for the angle of the forward inclination of the upper limb of the robot, so that the upper limb of the robot is always in a standing state. When the knee joint driving motor 5 stops driving, the lower leg 3 no longer swings, the small pulley 64 stops revolving with the lower leg 3, the small pulley 64 no longer rotates counterclockwise under the braking of the synchronous belt 62 and the large pulley 63, so as to stop the knee joint rotating shaft 1, at this time, the thigh 2 no longer inclines forward, and the leg structure of the robot remains in the squatting state. The synchronous belt 62 and the large pulley 63 bear the torque of the thigh 2 and the upper limb of the robot and maintain the spatial posture of the leg structure of the humanoid robot.

[0036] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present application, and are not intended to limit the protection scope of the present application. Although the present application has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that the technical solutions of the present application can be modified or replaced equivalently without departing from the essence and scope of the technical solutions of the present application.

Claims

1. A robot leg structure comprising a thigh, a shank and a knee joint pivot, a bottom end of the thigh being fixedly connected to the knee joint pivot, a top end of the shank being rotatably connected to the knee joint pivot, characterized in that, The knee joint driving motor is connected to the bottom end of the lower leg and can drive the lower leg to swing, and the thigh brake mechanism is arranged on one side of the knee joint rotating shaft. During the driving of the lower leg to swing by the knee joint driving motor, the thigh is tilted forward and drives the knee joint rotating shaft to rotate, and the thigh brake mechanism controls the tilting angle of the thigh. When the lower leg stops swinging, the thigh brake mechanism stops the knee joint rotating shaft to keep the thigh from moving. The thigh brake mechanism comprises a synchronous belt, a large pulley and a small pulley. The large pulley is coaxially installed on one side of the knee joint driving 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.

2. The robot leg structure according to claim 1, characterized in that The thigh brake mechanism further comprises a tension pulley, which presses the synchronous belt to realize the tensioning of the synchronous belt.

3. The robotic leg structure of claim 1, wherein, The tooth number ratio of the large pulley to the small pulley is 2:

1.

4. The robotic leg structure of claim 1, wherein, The thigh comprises an upper connecting rod and an upper support rib plate. The upper connecting rod is provided with two, and the two upper connecting rods are arranged side by side along the axis direction of the knee joint rotating shaft. The upper support rib plate is arranged between the two upper connecting rods and connects the two upper connecting rods to increase the rigidity of the thigh.

5. The robotic leg structure of claim 1, wherein, The lower leg comprises a lower connecting rod and a lower support rib plate. The lower connecting rod is provided with two, and the two lower connecting rods are arranged side by side along the axis direction of the knee joint rotating shaft. The lower support rib plate is arranged between the two lower connecting rods and connects the two lower connecting rods to increase the rigidity of the lower leg.

6. A robot waist and leg structure characterized by comprising: The robot leg structure comprises an upper limb connecting piece and a waist joint driving motor. The upper limb connecting piece is rotatably installed at the top end of the thigh, and the waist joint driving motor is installed on the thigh and can drive the upper limb connecting piece to swing forward and backward.

7. The robot waist and leg structure according to claim 6, characterized by The thigh adopts a bending structure and bends towards the back of the robot leg structure. When the leg structure of the robot is in an upright state, the axis of the waist joint driving motor and the axis of the knee joint driving motor are in the same vertical plane. The thigh adopts a bending structure and bends towards the back of the robot leg structure. When the leg structure of the robot is in an upright state, the axis of the waist joint driving motor and the axis of the knee joint driving motor are in the same vertical plane.

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