Parallel type four-connecting-rod mechanical leg for wheel-foot type robot and wheel-foot type robot with parallel type four-connecting-rod mechanical leg

Abstract

The utility model discloses a parallel type four-connecting-rod mechanical leg for a wheel-foot type robot, which comprises two thighs, a long shank and a short shank, and the thighs comprise a first thigh and a second thigh; the ends, close to each other, of the first thigh and the second thigh are used for obtaining power, the other end of the first thigh is hinged to one end of the long shank, the other end of the second thigh is hinged to one end of the short shank, the other end of the short shank is hinged to the preset position of the long shank, and the other end of the long shank is an operation end. According to the parallel type four-connecting-rod mechanical leg for the wheel-foot type robot, multi-degree-of-freedom movement of one leg can be achieved through the double steering engines, the wheel-foot type robot is further constructed according to the parallel type four-connecting-rod mechanical leg and idler wheels controlled by the wheel-foot switching mechanism, and fast switching of a wheel type mode and a foot type mode can be achieved.

Description

Technical Field

[0001] This utility model relates to a parallel four-bar linkage mechanical leg for a wheel-legged robot and a wheel-legged robot having the same, belonging to the field of wheel-legged robots. Background Technology

[0002] Existing wheeled robots are highly efficient on flat surfaces, but their wheel drive relies on continuously rotating motors, making it impossible to achieve discrete gait adjustments for legged mechanisms. This results in a 40%–60% decrease in traction on soft surfaces (sand, mud), leading to poor terrain adaptability. Traditional legged robots typically employ a configuration of three servo motors per leg. For example, the 2023 paper "A Twelve-DOF Bionic Quadruped Robot Based on STM32F4" (by Shi Zhicheng et al.), published in the journal *Electronic Manufacturing*, explicitly states that their designed bionic quadruped robot has "three MG90S servo motors per leg, totaling twelve." Some hybrid wheeled and legged robots use a separate design, resulting in complex structures and low mode-switching efficiency. Summary of the Invention

[0003] This invention provides a parallel four-bar linkage mechanical leg for a wheel-legged robot, which enables multi-degree-of-freedom movement of one leg through dual servo motors. Furthermore, based on the parallel four-bar linkage mechanical leg and the roller controlled by the wheel-leg switching mechanism, a wheel-legged robot can be constructed, which can realize rapid switching between wheeled and legged modes.

[0004] The technical solution of this utility model is:

[0005] According to a first aspect of the present invention, a parallel four-bar linkage mechanical leg for a wheel-legged robot is provided, comprising a thigh 11, a long lower leg 12, and a short lower leg 13. The thigh 11 consists of two legs, a first thigh and a second thigh. The ends of the first thigh and the second thigh that are close to each other are used to obtain power. The other end of the first thigh is hinged to one end of the long lower leg 12, and the other end of the second thigh is hinged to one end of the short lower leg 13. The other end of the short lower leg 13 is hinged to the long lower leg 12 at a predetermined position. The other end of the long lower leg 12 is the working end.

[0006] Furthermore, one end of the thigh 11 has a mounting hole a for cooperating with the power device, and the other end of the thigh 11 has a hinge hole b. The long lower leg 12 has a hinge hole c, a hinge hole d, and a mounting hole e from one end to the other. The hinge hole c is used to hinge one end of the long lower leg 12 to the hinge hole b of the first thigh. One end of the short lower leg 13 has a hinge hole f for hinged to the hinge hole b of the second thigh. The other end of the short lower leg 13 has a hinge hole g for mounting the short lower leg 13 to the second thigh. 3. The other end is hinged to the hinge hole d of the long lower leg 12; the distance from the centerline of the mounting hole a to the centerline of the hinge hole b is taken as the first distance, the distance from the centerline of the hinge hole c to the centerline of the hinge hole d is taken as the second distance, the distance from the centerline of the hinge hole f to the centerline of the hinge hole g is taken as the third distance, and the distance from the centerline of the hinge hole c to the centerline of the mounting hole e is taken as the fourth distance. The second distance and the third distance are equal, and the first distance < the second distance < the fourth distance.

[0007] According to a second aspect of this utility model, a wheel-legged robot is provided, comprising the aforementioned parallel four-link mechanical legs 1, and further comprising a wheel-leg switching mechanism 2, leg end wheel sets 14, a servo drive system 3, a main control system 4, a power supply module 5, and a body 6; the four-link mechanical legs 1 are arranged in four sections, with the two parallel four-link mechanical legs 1 on the left and the two parallel four-link mechanical legs 1 on the right arranged in a mirror-symmetrical manner about the mid-vertical plane of the torso; the body 6 is used to install the servo drive system 3, the main control system 4, and the power supply module 5; the servo... The drive system 3 provides power to the four-link mechanical leg 1. The main control system 4 outputs a PWM signal to control the servo drive system 3. The power supply module 5 provides power. The working end of the long leg 12 is equipped with a wheel-foot switching mechanism 2. The output shaft end of the wheel-foot switching mechanism 2 is equipped with a foot wheel set 14. The wheel-foot switching mechanism 2 drives the foot wheel set 14 to achieve wheel / foot mode switching. In wheel mode, the foot wheel set 14 touches the ground and drives. In foot mode, the foot wheel set 14 is locked and the four-link mechanical leg 1 performs the foot gait.

[0008] Furthermore, the main control system 4 includes an ESP32-S3 microcontroller, a WiFi module, and a PCA9685 servo control board. The ESP32-S3 microcontroller and the WiFi module are integrated to receive remote commands. The servos in the servo drive system 3 are connected to the PCA9685 servo control board via ribbon cables. The ESP32-S3 microcontroller communicates with the PCA9685 servo control board via the I²C protocol and outputs PWM signals to control the servos.

[0009] Furthermore, the power supply module 5 includes a 7.4V lithium battery and a TPS5450 step-down module. The 7.4V lithium battery is connected to the TPS5450 step-down module with a filter capacitor through the XT60 interface to output a 5V voltage to power the servo drive system 3 and output a 3.3V voltage to power the main control system 4.

[0010] The beneficial effects of this utility model are as follows: Through the symmetrical design of the parallel four-bar linkage mechanical legs, this utility model reduces the number of servo motors for legged movement of the wheel-legged robot to 8 (33% less than similar legged robots), while retaining 4 degrees of freedom of movement capability; furthermore, through the integrated wheel-leg switching mechanism using MG90S servo motors to drive the foot rollers, the wheel-leg mode locking is completed within 0.5 seconds without mechanical reconfiguration, solving the problems of slow mode switching and structural redundancy in the prior art, achieving efficient mode conversion, and combining speed and terrain adaptability. Attached Figure Description

[0011] Figure 1 This is a schematic diagram of a wheeled robot structure provided according to an embodiment;

[0012] Figure 2 This is a schematic diagram of a parallel four-bar linkage mechanical leg structure provided in the embodiment;

[0013] Figure 3 This is a schematic diagram of the structure of a long lower leg;

[0014] Figure 4 This is a partial schematic diagram of a parallel four-bar linkage mechanical leg;

[0015] Figure 5 This is a schematic diagram of the servo drive system, power supply module, and main control system in a wheeled robot.

[0016] The labels in the diagram are as follows: 1-Parallel four-bar linkage mechanical leg, 2-Wheel-foot switching mechanism, 3-Servo drive system, 4-Main control system, 5-Power supply module, 6-Fuselage, 61-Top cover, 62-Side plate, 63-Base plate, 11-Thigh leg, 12-Long lower leg, 13-Short lower leg, 14-Foot end wheel set. Detailed Implementation

[0017] The utility model will be further described below with reference to the accompanying drawings and embodiments, but the scope of the utility model is not limited to the description.

[0018] Example 1: As Figures 1-5As shown, according to a first aspect of the present invention, a parallel four-bar linkage mechanical leg for a wheel-legged robot is provided, comprising a thigh 11, a long lower leg 12, and a short lower leg 13. The thigh 11 consists of two legs, a first thigh and a second thigh. The ends of the first thigh and the second thigh that are close to each other are used to obtain power. The other end of the first thigh is hinged to one end of the long lower leg 12, and the other end of the second thigh is hinged to one end of the short lower leg 13. The other end of the short lower leg 13 is hinged to the long lower leg 12 at a predetermined position. The other end of the long lower leg 12 is the working end.

[0019] Furthermore, the thigh 11 has a mounting hole a at one end and a hinge hole b at the other end. The long calf 12 has a hinge hole c, a hinge hole d, and a mounting hole e from one end to the other. The hinge hole c is used to hinge one end of the long calf 12 to the hinge hole b of the first thigh. The short calf 13 has a hinge hole f at one end for hinged to the hinge hole b of the second thigh. The short calf 13 has a hinge hole g at the other end for hinged to the other end of the short calf 13. It is hinged to the hinge hole d of the long lower leg 12; the distance from the centerline of the mounting hole a to the centerline of the hinge hole b is taken as the first distance, the distance from the centerline of the hinge hole c to the centerline of the hinge hole d is taken as the second distance, the distance from the centerline of the hinge hole f to the centerline of the hinge hole g is taken as the third distance, and the distance from the centerline of the hinge hole c to the centerline of the mounting hole e is taken as the fourth distance. The second distance and the third distance are equal, and the first distance < the second distance < the fourth distance. For example, the ratio of the first distance to the second distance is 1:1.92~2, and the ratio of the first distance to the fourth distance is 1:2.28~2.5, etc. Figure 2 The first distance is 70mm, the second distance is 135mm, and the fourth distance is 160mm.

[0020] According to a second aspect of the present invention, a parallel four-bar linkage mechanical leg for a wheeled robot is provided, including a parallel four-bar linkage mechanical leg 1, a wheel-leg switching mechanism 2, a leg end wheel set 14, a servo drive system 3, a main control system 4, a power supply module 5, and a body 6.

[0021] The parallel four-link mechanical leg 1 consists of four legs, with the two parallel four-link mechanical legs 1 on the left and the two parallel four-link mechanical legs 1 on the right arranged in a mirror-symmetrical manner about the mid-vertical plane of the torso. The body 6 is used to install the servo drive system 3, the main control system 4, and the power supply module 5. The servo drive system 3 is used to provide power to the four-link mechanical leg 1, the main control system 4 outputs PWM signals to control the servo drive system 3, and the power supply module 5 is used to supply power. The working end of the long lower leg 12 is equipped with a wheel-foot switching mechanism 2, and the output shaft end of the wheel-foot switching mechanism 2 is equipped with a foot wheel assembly 14. The wheel-foot switching mechanism 2 drives the foot wheel assembly 14 to achieve wheel / foot mode switching. In wheel mode, the foot wheel assembly 14 touches the ground and drives. In foot mode, the foot wheel assembly 14 is locked and the four-link mechanical leg 1 performs the foot gait.

[0022] Furthermore, the fuselage 6 includes a base plate 63, side plates 62 mounted on opposite sides of the base plate 63, and an upper cover 61 covering the base plate 63 and side plates 62. The interior of the fuselage 63, side plates 62, and upper cover 61 is supported by carbon fiber tubes 64. The 3D-printed PLA upper cover 61 is fixed to the carbon fiber side plates 62 with bolts, and the PLA upper cover 61 is fixed to the PLA base plate 63 with clips and hinges. Furthermore, the combination of the carbon fiber side plates and the PLA printed parts in the fuselage 6 features an internal hollow design to reduce weight, and the streamlined shape of the external carbon fiber side plates 62 reduces wind resistance.

[0023] Furthermore, the thigh 11, the long calf 12, and the short calf 13 are made of 3D printed PLA material.

[0024] During installation, four four-link mechanical legs 1 are symmetrically distributed at the four corners of the fuselage 6. The legs 11 are connected to the NANGU servo motors in the servo drive system 3, which are fixed to the carbon fiber side plates 62, via bolts and micro-bearings (the micro-bearings form a clearance fit with the legs 11 to distribute some of the impact force transmitted to the servo motor shaft). The other ends of the first and second legs are connected to the long lower legs 12 and short lower legs 13, respectively, via micro-bearings and cylindrical pins (the other end of the legs has an open slot design with through holes aligned with the long lower legs 12 and short lower legs 13; the micro-bearings are placed in the holes of the long lower legs 12 and short lower legs 13 to form an interference fit; the cylindrical pins pass through the through holes to fix the legs and simultaneously create a rotational relationship between the legs 11 and the long lower legs 12 and short lower legs 13). For example, 693-2z [3*8*3] micro-bearings with a wear resistance of grade 3 and 40cr bearings with an inner diameter of 3 are used. (Quenched cylindrical pins are used to connect the legs), forming a rotatable parallel leg structure. The wheel-foot switching mechanism 2 uses a servo motor, which is mounted on the working end of the long lower leg 12 via a housing. The output shaft of the servo motor is connected to the foot end wheel assembly 14 via the mounting hole e. The foot end wheel assembly 14 uses rollers, and the surface of the rollers is covered with rubber and has a diamond-shaped anti-slip pattern, which increases the ground contact area by 20% in wheel mode and prevents slippage.

[0025] For example:

[0026] The wheel-foot switching mechanism 2 uses MG90S servo motors. Four MG90S servo motors drive the rollers. In wheel mode, the MG90S servo motors drive the ground-contacting rollers to move in wheel mode. In foot mode, the MG90S servo motors are locked, and the parallel four-bar mechanical legs perform Trot gait.

[0027] The servo drive system 3 uses eight NANGU servo motors with a torque of 20 kg·cm to drive the leg joints. The servo motors are connected to the joint shaft of the thigh in the four-link mechanical leg 1 through a metal servo disc to ensure torque transmission efficiency.

[0028] The main control system 4 includes an ESP32-S3 microcontroller, a WiFi module, and a PCA9685 servo control board. The ESP32-S3 microcontroller, fixed under the PLA upper cover 61, is integrated with the WiFi module to receive remote commands. The PCA9685 servo control board is mounted next to the microcontroller via copper pillars to reduce signal interference. All servos are connected to the PCA9685 servo control board via ribbon cables. The ESP32-S3 microcontroller processes inverse kinematics algorithms and gait planning, receives remote commands via the WiFi module, issues motion commands via a web interface, communicates with the PCA9685 servo control board via the I²C protocol, and outputs PWM signals to control the servos.

[0029] The power supply module 5 includes a 7.4V lithium battery and a TPS5450 step-down module. The 7.4V lithium battery is installed in the center of the base plate 63 and secured with nylon cable ties. The TPS5450 step-down module is arranged adjacent to the lithium battery. The 7.4V lithium battery is connected to the TPS5450 step-down module with a filter capacitor via an XT60 interface to output a stable 5V voltage to power the servo drive system 3 and a stable 3.3V voltage to power the main control system 4. The power lines are routed through the cable trays in the carbon fiber side plate 61 to avoid interference with the mechanical structure.

[0030] By applying the above technical solution, this utility model has the following advantages:

[0031] 1. Quick mode switching: Actual test showed that the time to switch from wheeled to legged mode is ≤0.5 seconds, with a maximum load capacity of 5kg;

[0032] 2. Low cost: Modular design reduces assembly and maintenance costs;

[0033] 3. High stability: The combination of compound cycloidal trajectory planning and parallel four-bar linkage mechanical legs improves the smoothness of motion.

[0034] The specific embodiments of the present invention have been described in detail above with reference to the accompanying drawings. However, the present invention is not limited to the above embodiments. Within the scope of knowledge possessed by those skilled in the art, various changes can be made without departing from the spirit of the present invention.

Claims

1. A parallel four-bar linkage mechanical leg for a wheel-legged robot, characterized by, It includes a thigh (11), a long calf (12), and a short calf (13). The thigh (11) consists of two thighs, a first thigh and a second thigh. The ends of the first thigh and the second thigh that are close to each other are used to obtain power. The other end of the first thigh is hinged to one end of the long calf (12), the other end of the second thigh is hinged to one end of the short calf (13), the other end of the short calf (13) is hinged to the long calf (12) at a preset position, and the other end of the long calf (12) is the working end.

2. The parallel four-bar linkage mechanical leg for a wheel-legged robot according to claim 1, wherein The thigh (11) has a mounting hole a for cooperating with the power device at one end and a hinge hole b at the other end. The long calf (12) has a hinge hole c, a hinge hole d, and a mounting hole e from one end to the other. The hinge hole c is used to hinge one end of the long calf (12) to the hinge hole b of the first thigh. The short calf (13) has a hinge hole f at one end for hingeing the short calf (13) to the hinge hole b of the second thigh. The short calf (13) has a hinge hole g at the other end for hingeing the short calf (13) to the second thigh. The other end of the leg (13) is hinged to the hinge hole d of the long lower leg (12); the distance from the center axis of the mounting hole a to the center axis of the hinge hole b is taken as the first distance, the distance from the center axis of the hinge hole c to the center axis of the hinge hole d is taken as the second distance, the distance from the center axis of the hinge hole f to the center axis of the hinge hole g is taken as the third distance, and the distance from the center axis of the hinge hole c to the center axis of the mounting hole e is taken as the fourth distance. The second distance and the third distance are equal, and the first distance < the second distance < the fourth distance.

3. A wheel-legged robot, characterized in that, The system includes the parallel four-bar mechanical leg (1) as described in claim 1, and also includes a wheel-foot switching mechanism (2), a foot wheel assembly (14), a servo drive system (3), a main control system (4), a power supply module (5), and a fuselage (6); The four-link mechanical leg (1) consists of four legs, with the two parallel four-link mechanical legs (1) on the left and the two parallel four-link mechanical legs (1) on the right arranged in a mirror-symmetrical manner about the mid-vertical plane of the torso; the fuselage (6) is used to install the servo drive system (3), the main control system (4), and the power supply module (5); the servo drive system (3) is used to provide power to the four-link mechanical leg (1), the main control system (4) outputs PWM signals to control the servo drive system (3), and the power supply module (5) is used to supply power; the working end of the long lower leg (12) is equipped with a wheel-foot switching mechanism (2), and the output shaft end of the wheel-foot switching mechanism (2) is equipped with a foot wheel assembly (14). The wheel-foot switching mechanism (2) drives the foot wheel assembly (14) to achieve wheel / foot mode switching. In wheel mode, the foot wheel assembly (14) touches the ground and drives, and in foot mode, the foot wheel assembly (14) is locked and the four-link mechanical leg (1) performs the foot gait.

4. The wheel-legged robot according to claim 3, characterized in that, The main control system (4) includes an ESP32-S3 microcontroller, a WiFi module, and a PCA9685 servo control board. The ESP32-S3 microcontroller and the WiFi module are integrated to receive remote commands. The servos in the servo drive system (3) are connected to the PCA9685 servo control board via ribbon cables. The ESP32-S3 microcontroller communicates with the PCA9685 servo control board via I... 2 The C protocol communicates with the PCA9685 servo control board and outputs PWM signals to control the servo.

5. The wheel-legged robot according to claim 3, characterized in that, The power supply module (5) includes a 7.4V lithium battery and a TPS5450 step-down module. The 7.4V lithium battery is connected to the TPS5450 step-down module with a filter capacitor through the XT60 interface to output a 5V voltage to power the servo drive system (3) and output a 3.3V voltage to power the main control system (4).

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