Wheel-foot type mobile robot and operation method thereof

Abstract

The invention discloses a wheel-foot type mobile robot and an operation method thereof, and the wheel-foot type mobile robot mainly comprises a robot body, four driving legs which are connected with the robot body and have the same structure, and a controller ECU and a sensing unit which are arranged on the robot body. Each driving leg is composed of an upper motor, an upper leg, a lower leg, a knee motor, a clutch, a driving wheel and the like. Through the integrated design of the knee motor and the clutch, the single knee motor can respectively drive the lower leg and the driving wheel by means of switching of the clutch, a wheel set driving motor does not need to be additionally arranged, and through the one-motor dual-purpose structure, the hardware number and the overall weight of a power system are greatly reduced; the equipment manufacturing and maintenance cost is reduced, energy loss caused by simultaneous operation of multiple motors is avoided, the cruising ability of the robot is effectively improved, and the robot is particularly suitable for field long-time operation scenes.

Description

Technical Field

[0001] This invention relates to the field of robot mobility technology, specifically to a wheeled legged mobile robot and its operation method. Background Technology

[0002] In the field of robotic mobility technology, quadruped robots, with their adaptability to complex terrain, have been widely used in various scenarios such as military reconnaissance, disaster relief, and mountain transportation. Currently, mainstream quadruped robots are mainly divided into two categories: pure-legged and hybrid wheel-legged. Both types have their own characteristics, but both also have significant performance limitations. For pure-legged quadruped robots, the core driving mechanism is the swinging of the leg joints, achieving gait adjustment through multi-joint coordinated control. A typical example is the quadruped robot disclosed in patent CN112874651B. The core advantage of this type of robot lies in its outstanding obstacle-crossing ability, adapting to unstructured terrain such as stairs, gravel roads, and steep slopes, and possessing strong reliability in complex environments. However, limited by the joint swinging motion mechanism, pure-legged robots have low walking efficiency and a significantly insufficient upper speed limit, making it difficult to meet the needs of rapid movement on flat surfaces. For hybrid wheel-legged quadruped robots, the design concept typically involves adding wheels to the bottom of the legs of a traditional quadruped robot, achieving functional complementarity through the coordinated movement of the wheels and legs.

[0003] While hybrid wheel-legged robots outperform purely legged robots in terms of speed on flat surfaces, existing solutions generally suffer from excessive energy consumption and insufficient endurance. The root cause lies in the fact that the wheel drive system requires four additional independent drive units. Combined with the leg drive system, this significantly increases the overall load on the power system, leading to a faster energy consumption rate and severely limiting the robot's ability to operate in the field for extended periods.

[0004] In summary, existing quadruped robot technology cannot simultaneously meet the three core requirements of "efficient movement", "low energy consumption" and "adaptation to complex terrain", and a brand-new structural design scheme is urgently needed to break through the current technical bottleneck. Summary of the Invention

[0005] The purpose of this invention is to overcome the shortcomings of current quadruped robots, such as low mobility, high energy consumption, and inability to adapt to complex terrain, and to provide a wheel-legged mobile robot and its operation method.

[0006] The objective of this invention is achieved through the following technical solution: a wheeled mobile robot, mainly composed of a machine body, four identical drive legs connected to the machine body, and a controller ECU and sensing unit mounted on the machine body. Each drive leg consists of an upper motor, an upper leg, a lower leg, a knee motor, a clutch, and a drive wheel. The upper motor is connected to the machine body, the upper end of the upper leg is connected to the shaft of the upper motor, and the knee motor is located at the lower end of the upper leg and connected to the upper end of the lower leg. The drive wheel is connected to the shaft of the knee motor via a clutch, and the knee motor can drive the rotation of the lower leg and the drive wheel and switch between them via the clutch.

[0007] Furthermore, the clutch consists of a driving disc, a driven disc one, and a driven disc two. The lower end of the upper leg is fixedly connected to the stator of the knee motor, and a connecting piece is fixedly connected to the rotor of the knee motor. The driving disc is fixedly connected to the connecting piece via a transmission shaft. The lower leg is connected to the driven disc two, and the drive wheel is fixedly connected to the driven disc one. The drive wheel, driven disc one, and driven disc two are all fixedly connected to the transmission shaft. When the machine body is in a foot-like posture, the driving disc drives driven disc two to rotate, and the knee motor drives the lower leg to rotate. When the machine body is in a wheel-like posture, the driving disc drives driven disc one to rotate, and the knee motor drives the drive wheel to rotate.

[0008] The sensing unit consists of a visual sensor connected to the controller ECU for acquiring image information of the robot's surrounding environment; a lidar connected to the controller ECU for acquiring distance information of the surrounding environment and constructing a three-dimensional model of the surrounding environment; an inertial measurement unit connected to the controller ECU for sensing the robot's own posture and motion state; and a force sensor connected to the controller ECU for measuring the contact force between the robot and the ground or an object.

[0009] A method for operating a wheeled mobile robot, comprising the following steps: S1. When the sensing unit detects that the lower leg and the upper leg form an angle of 45° to 135°, it triggers the wheel mode switching signal. The controller ECU controls the upper motor to gradually stop moving, so that the robot stops at the current position. At this time, the force sensor monitors the contact force between the lower leg and the ground to ensure that the robot stops smoothly. S2. The controller ECU controls the upper and knee motors to gradually retract the upper and lower legs upwards and adjust the robot's posture to a suitable angle for wheeled movement. The sensor unit monitors the position and angle information of the upper and lower legs in real time and feeds it back to the controller ECU. S3. Once the lower leg is retracted into position, the clutch is switched. The controller ECU sends a command to the knee motor according to the robot's preset speed and direction of movement, causing the drive wheel to start rotating, and the robot begins to move in wheel mode. S4. When the leg mode switching signal is triggered, the controller ECU sends a command to the knee motor to gradually decelerate the drive wheel. The controller ECU controls the upper motor and knee motor to move, so that the upper and lower legs gradually extend downward and adjust the robot's posture to an angle suitable for leg walking. The sensor unit monitors the position and angle information of the upper and lower legs in real time and feeds it back to the controller ECU. S5. Once the lower leg is close to the ground and the posture is adjusted, the clutch is switched, and the controller ECU, based on the feedback information from the sensor unit, enables the robot to begin walking in a stable legged posture.

[0010] As a preferred method, the "trigger foot mode switching signal" mentioned in step S4 is triggered automatically or manually by remote control commands.

[0011] Compared with the prior art, the present invention has the following advantages and beneficial effects: (1) The present invention integrates the knee motor and the clutch, allowing a single knee motor to drive the lower leg and the drive wheel separately by switching the clutch, without the need to add an additional wheel drive motor. This "one motor for two purposes" structure greatly reduces the number of hardware components and the overall weight of the power system, which not only reduces the manufacturing and maintenance costs of the equipment, but also avoids the energy loss of multiple motors running at the same time, effectively improving the robot's endurance, and is especially suitable for long-term field operation scenarios.

[0012] (2) This invention uses the angle between the lower leg and the upper leg of 45° to 135° as the core mechanical condition for triggering the wheel mode. Combined with the force sensor monitoring the ground contact force to ensure a smooth stop, and relying on the multi-data fusion of vision sensor, lidar and IMU, it can accurately identify terrain features (such as stairs, obstacles and slopes) to provide environmental basis for switching to the leg mode. This design of the invention allows the robot to move efficiently in wheel mode on flat roads and quickly switch to leg mode to flexibly overcome obstacles in complex terrain, truly achieving the dual requirements of "efficiency" and "adaptability".

[0013] (3) Each drive leg in this invention contains only two power sources: an upper motor and a knee motor. The power transmission path is simplified by using a clutch, which reduces the number of easily damaged parts such as drive shafts and independent wheel drive motors. At the same time, the closed-loop control of the sensing unit and the controller ECU can correct the action deviation in time, avoid mechanical jamming or power conflict, and significantly improve the overall reliability and maintenance convenience of the equipment. Attached Figure Description

[0014] Figure 1 This is a schematic diagram of the structure of the robot of the present invention when it moves in a legged mode; Figure 2This is a schematic diagram of the robot of the present invention when it moves in a wheeled mode; Figure 3 This is a schematic cross-sectional view of the clutch of the present invention when it is connected to the knee motor. Figure 4 This is a schematic diagram of the process when the robot of the present invention moves in a cooperative mode.

[0015] The reference numerals in the above figures are named as follows: 1-Machine body, 2-Upper motor, 3-Upper leg, 4-Lower leg, 5-Knee motor, 6-Clutch, 7-Drive wheel, 8-Connector, 9-Transmission shaft, 61-Driven disc, 62-Driven disc one, 63-Driven disc two. Detailed Implementation

[0016] The present invention will be further described in detail below with reference to embodiments, but the implementation of the present invention is not limited thereto.

[0017] Example

[0018] like Figures 1-4 As shown, the wheeled mobile robot described in this embodiment mainly consists of a machine body 1, a controller ECU and a sensing unit installed inside the machine body 1, and four drive legs installed at the left front, right front, left rear and right rear of the machine body 1.

[0019] The controller ECU receives signals from various sensors, analyzes and calculates them, and then sends commands to the actuators to control subsequent drive and shifting operations.

[0020] The sensing unit includes: an image information vision sensor connected to the controller ECU for acquiring images and other information about the robot's surrounding environment; a lidar connected to the controller ECU for acquiring distance information about the surrounding environment and constructing a three-dimensional model of the surrounding environment; an inertial measurement unit connected to the controller ECU for sensing the robot's own posture and motion state; and a force sensor connected to the controller ECU for measuring the contact force between the robot and the ground or an object.

[0021] In this embodiment, the four drive legs have identical structures. Each drive leg consists of an upper motor 2, an upper leg 3, a lower leg 4, a knee motor 5, a clutch 6, and a drive wheel 7. During connection, the upper motor 2 is connected to the machine body 1, and the upper end of the upper leg 3 is connected to the rotating shaft of the upper motor 2, so that the rotation of the upper motor 2 drives the movement of the upper leg 3.

[0022] A knee motor 5 is located at the lower end of the upper leg 3 and connected to the upper end of the lower leg 4, while the drive wheel 7 is connected to the shaft of the knee motor 5 via a clutch 6. The lower end of the upper leg 3 is connected to the stator of the knee motor 5, and the clutch 6 is connected to the shaft of the knee motor 5 to ensure that the knee motor 5 can drive the rotation of the lower leg 4 and the drive wheel 7 and switch between them via the clutch 6. The clutch 6 consists of a driving disc 61, a driven disc one 62, and a driven disc two 63, and its connection relationship with other components is as follows: Figure 3 As shown. During connection, the lower end of the upper leg 3 is fixedly connected to the stator of the knee motor 5 by screws, and the rotor of the knee motor 5 is fixedly connected to the connector 8 by screws.

[0023] The driving disc 61 is fixedly connected to the connecting member 8 via the transmission shaft 9, the lower leg 4 is connected to the driven disc 63, and the driving wheel 7 is fixedly connected to the driven disc 62. The driving wheel 7, the driven disc 62, and the driven disc 63 are all fixedly connected to the transmission shaft 9 to ensure that the knee motor 5 can drive the driving wheel 7, the driven disc 62, and the driven disc 63 respectively via the transmission shaft 9.

[0024] Specifically, when the robot is in a legged posture, the active disk 61 drives the driven disk 63 to rotate, thereby enabling the knee motor 5 to drive the lower leg 4 to rotate; when the robot is in a wheeled posture, the active disk 61 drives the driven disk 62 to rotate, thereby enabling the knee motor 5 to drive the drive wheel 7 to rotate.

[0025] The robot in this embodiment can move in both wheeled and legged modes. The wheeled mode is suitable for flat terrain, achieving efficient and low-power movement. Relying on the power transmission path of the knee motor 5, clutch 6, and drive wheels 7, it has significant advantages on flat surfaces such as city roads and factory passageways. Firstly, the drive wheels 7 experience rolling friction with the ground, resulting in less frictional resistance compared to the alternating leg support in legged mode. The knee motor 5 does not need to output excessive torque to drive the robot at high speeds, improving movement efficiency, reducing motor energy consumption, and extending battery life. Secondly, wheeled movement offers higher stability. Combined with real-time posture monitoring by the inertial measurement unit, the robot can maintain uniform linear motion, avoiding the bumps caused by gait adjustments in legged walking. This makes it suitable for scenarios requiring high stability, such as transporting precision instruments and factory inspections.

[0026] The described legged mode is specifically designed for tackling complex terrain. It uses a knee motor 5 to drive the lower leg 4 to swing, while the upper leg 3 is adjusted by the upper motor 2. This allows for flexible handling of unstructured terrain, overcoming the limitations of the wheeled mode. For example, when encountering obstacles 15-30cm high, the legged mode can directly traverse them using a "leg lift-jump" motion, without needing to detour. This strong terrain adaptability allows the robot to be used in scenarios such as disaster relief and mountain exploration, where purely wheeled robots are difficult to access.

[0027] In this embodiment, the switching between wheeled and legged modes is achieved through a closed-loop logic of "perception-decision-switching," the process of which is as follows: Figure 3 As shown, the specific steps include: S1. When the sensing unit detects that the lower leg 4 and the upper leg 3 form an angle of 45° to 135°, it triggers the wheel mode switching signal. The controller ECU controls the upper motor 2 to gradually stop moving, so that the robot stops at the current position. At this time, the force sensor monitors the contact force between the lower leg 4 and the ground to ensure that the robot stops smoothly.

[0028] The sensing of the 45°–135° angle between the lower leg 4 and the upper leg 3 in this step is accomplished by the inertial measurement unit (IMU). When the IMU senses this angle range, it transmits the relevant information to the controller ECU, which then performs the corresponding calculations and issues control commands.

[0029] S2. The controller ECU controls the upper motor 2 and the knee motor 5 to gradually retract the upper leg 3 and lower leg 4 upwards, and adjusts the robot's posture to an angle suitable for wheeled movement. The sensor unit monitors the position and angle information of the upper leg 3 and lower leg 4 in real time and feeds it back to the controller ECU.

[0030] S3. When the lower leg 4 is retracted into place, the clutch 6 completes the switching. The controller ECU sends a command to the knee motor 5 according to the robot's preset speed and direction of movement, so that the drive wheel 7 starts to rotate and the robot begins to move in wheel mode.

[0031] S4. When the leg mode switching signal is triggered, the controller ECU sends a command to the knee motor 5 to gradually decelerate the drive wheel 7. The controller ECU controls the upper motor 2 and the knee motor 5 to move, so that the upper leg 3 and the lower leg 4 gradually extend downward and adjust the robot's posture to an angle suitable for leg walking. The sensor unit monitors the position and angle information of the upper leg 3 and the lower leg 4 in real time and feeds it back to the controller ECU.

[0032] The triggering of the foot-based mode switching signal mentioned in this step includes two methods: manual triggering via remote control commands, i.e., manual active triggering and automatic triggering. Manual active triggering is the most direct method, where the operator actively issues a switching command based on needs. Besides remote control, common methods include: physical button triggering, which requires a mode switching button (such as an emergency switch button or a preset mode selection button) on the machine body 1, directly generating a trigger signal upon pressing; host computer command triggering, which involves connecting to a computer, tablet, or other host device and clicking the "mode switching" button in the control software interface to send a command signal; and voice / gesture triggering, which requires the machine body 1 to support voice commands or gesture recognition (such as specific body movements), indirectly generating a trigger command by parsing human-computer interaction signals.

[0033] The automatic triggering means that no manual intervention is required. At this time, the machine body 1 will automatically generate a mode switching trigger signal based on preset conditions or environmental feedback.

[0034] In this embodiment, the trigger for the foot-type mode switching signal is preferably triggered manually via a remote control command.

[0035] S5. Once leg 4 is close to the ground and its posture is adjusted, clutch 6 switches, and the controller ECU, based on feedback from the sensor unit, enables the robot to begin walking in a stable legged posture.

[0036] As described above, the present invention can be well implemented.

Claims

1. A wheeled mobile robot, mainly composed of a machine body (1), four drive legs connected to the machine body (1) and having the same structure, and a controller ECU and a sensing unit disposed on the machine body (1), characterized in that, Each drive leg consists of an upper motor (2), an upper leg (3), a lower leg (4), a knee motor (5), a clutch (6), and a drive wheel (7). The upper motor (2) is connected to the machine body (1), the upper end of the upper leg (3) is connected to the shaft of the upper motor (2), and the knee motor (5) is located at the lower end of the upper leg (3) and connected to the upper end of the lower leg (4). The drive wheel (7) is connected to the shaft of the knee motor (5) through the clutch (6), and the knee motor (5) can drive the rotation of the lower leg (4) and the drive wheel (7) and switch between them through the clutch (6).

2. The wheel-legged mobile robot according to claim 1, characterized in that, The clutch (6) consists of an active disc (61), a driven disc one (62) and a driven disc two (63). The lower end of the upper leg (3) is fixedly connected to the stator of the knee motor (5). A connecting piece (8) is fixedly connected to the rotor of the knee motor (5). The active disc (61) is fixedly connected to the connecting piece (8) through the transmission shaft (9). The lower leg (4) is connected to the driven disc two (63). The drive wheel (7) is fixedly connected to the driven disc one (62). The drive wheel (7), the driven disc one (62) and the driven disc two (63) are all fixedly connected to the transmission shaft (9). When the robot is in a legged posture, the active disc (61) drives the driven disc two (63) to rotate, and the knee motor (5) drives the lower leg (4) to rotate. When the robot is in a wheeled posture, the active disc (61) drives the driven disc one (62) to rotate, and the knee motor (5) drives the drive wheel (7) to rotate.

3. A wheel-legged mobile robot according to claim 2, characterized in that, The sensing unit consists of a visual sensor connected to the controller ECU for acquiring image information of the robot's surrounding environment; a lidar connected to the controller ECU for acquiring distance information of the surrounding environment and constructing a three-dimensional model of the surrounding environment; an inertial measurement unit connected to the controller ECU for sensing the robot's own posture and motion state; and a force sensor connected to the controller ECU for measuring the contact force between the robot and the ground or an object.

4. A method for operating a wheeled mobile robot according to any one of claims 1 to 3, characterized in that it includes the following steps: S1. When the sensing unit senses that the lower leg (4) and the upper leg (3) form an angle of 45° to 135°, the wheel mode switching signal is triggered. The controller ECU controls the upper motor (2) to gradually stop moving, so that the robot stops at the current position. At this time, the force sensor monitors the contact force between the lower leg (4) and the ground to ensure that the robot stops smoothly. S2. The controller ECU controls the upper motor (2) and the knee motor (5) to gradually retract the upper leg (3) and the lower leg (4) upwards and adjust the robot's posture to a suitable angle for wheeled movement. The sensor unit monitors the position and angle information of the upper leg (3) and the lower leg (4) in real time and feeds it back to the controller ECU. S3. When the lower leg (4) is retracted into place, the clutch (6) is switched. The controller ECU sends a command to the knee motor (5) according to the robot's preset speed and direction of movement, so that the drive wheel (7) starts to rotate and the robot starts to move in wheel mode. S4. When the foot mode switching signal is triggered, the controller ECU sends a command to the knee motor (5) to gradually decelerate the drive wheel (7). The controller ECU controls the upper motor (2) and the knee motor (5) to move, so that the upper leg (3) and the lower leg (4) gradually extend downward and adjust the robot's posture to a suitable angle for foot walking. The sensor unit monitors the position and angle information of the upper leg (3) and the lower leg (4) in real time and feeds it back to the controller ECU. S5. When the lower leg (4) approaches the ground and the posture is adjusted, the clutch (6) completes the switching. The controller ECU, based on the feedback information from the sensor unit, enables the robot to start walking in a stable foot posture.

5. The method for operating a wheeled mobile robot according to claim 4, characterized in that, The "trigger foot mode switching signal" mentioned in step S4 can be triggered automatically or manually via remote control commands.

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