Wheel-foot robot leg telescoping mechanism and lightweight design method

Abstract

The invention discloses a wheel-foot robot leg telescoping mechanism and a lightweight design method, and relates to the technical field of program control robots, the wheel-foot robot leg telescoping mechanism comprises a machine body, the machine body is connected with a connecting rod through a first rotating shaft, the other end of the connecting rod is connected with a connecting seat through a second rotating shaft, and a driving motor, a driving wheel and a swingable auxiliary leg are integrated on the connecting seat; auxiliary wheels are arranged at the bottoms of the auxiliary legs, fixing grooves with electromagnetic locks are formed in the outer wall of the fuselage and used for storing and locking the auxiliary wheels, a high-speed moving mode and a high-trafficability mode are defined through the method, and the control unit collects road surface information in real time to control the driving motor and the driving assembly to complete unfolding and storing of the auxiliary wheels and fuselage posture adjustment. Through the highly-integrated storable leg mechanism and double-connecting-rod inclined layout, in combination with the gravity center track and zero moment point real-time pre-estimation regulation and control, smooth, stable and self-adaptive rapid switching between modes is achieved, and the problems that a traditional wheel-foot robot is heavy in structure, switching lags, stability is poor, and energy consumption is high are solved.

Description

Technical Field

[0001] This invention relates to the field of program-controlled robot technology, and more specifically, to a leg extension mechanism for wheeled robots and a lightweight design method. Background Technology

[0002] Wheeled robots have the advantage of high-speed and efficient movement on flat surfaces, while legged robots have superior maneuverability in complex and irregular terrain. To balance speed and maneuverability, the concept of wheeled-legged robots has been proposed in existing technologies. However, existing hybrid wheel-legged systems often have relatively independent wheel and leg structures or complex switching mechanisms, resulting in a slow and disjointed transition from wheeled to legged gait, hindering rapid response and impacting the robot's operational efficiency in dynamically changing environments. To achieve both movement modes, many designs employ a superimposed structure, leading to heavy and inertial leg mechanisms. This not only increases energy consumption and reduces flexibility but also makes stability issues, even tipping over, more likely during mode switching or legged movement due to difficulties in adjusting the center of gravity.

[0003] Therefore, a leg extension mechanism and lightweight design method for wheeled robots are proposed to address the above problems. Summary of the Invention

[0004] In order to overcome the above-mentioned defects of the prior art, the present invention provides a leg extension mechanism for a wheeled robot and a lightweight design method to solve the problems mentioned in the background art.

[0005] To achieve the above objectives, the present invention provides the following technical solution: a leg extension mechanism for a wheeled robot, comprising a body, a first rotating shaft disposed on the outer wall of the body, a connecting rod disposed on one side of the first rotating shaft, a second rotating shaft disposed on one side of the connecting rod, a connecting seat disposed on one side of the second rotating shaft, an active wheel and a drive motor disposed on the connecting seat, the drive motor being configured to: drive the active wheel to rotate, or drive the auxiliary leg to swing around the second rotating shaft, an auxiliary wheel disposed at the bottom of the auxiliary leg, and a fixing groove disposed on the outer wall of the body, wherein when the auxiliary leg swings upward, the auxiliary wheel can be retracted and locked in the fixing groove.

[0006] Preferably, a control unit is provided inside the body, and a drive assembly is provided at the bottom of the body.

[0007] Preferably, the connection point between the auxiliary leg and the connecting seat is located on one side of the axis of the driving wheel, so that when the auxiliary leg rotates, the grounding point of the auxiliary wheel is located outside the grounding point of the driving wheel.

[0008] Preferably, the connecting rod is provided in two sets, and the two sets of connecting rods are arranged obliquely along the vertical direction of the outer wall of the machine body, and the connecting rod is made of lightweight high-strength composite material.

[0009] Preferably, an electromagnetic lock is provided inside the fixing groove, and the auxiliary wheel is locked by the electromagnetic lock after it moves into the fixing groove through the folding movement of the auxiliary leg.

[0010] A lightweight design method for wheeled robots includes the following steps: S1. Define the two operating modes of the robot: In high-speed movement mode, the auxiliary wheel is stored and locked in the fixed groove, and the driving wheel acts as the main driving wheel, rolling forward in contact with the ground. In the high passability mode, the auxiliary wheel rotates downward and unfolds to contact the ground and lifts the body, while the drive motor drives the auxiliary leg to swing back and forth to achieve foot-like stepping motion; S2. During operation, the control unit continuously collects and analyzes road surface information ahead, and calculates the required operating mode based on a preset switching decision algorithm. S3. Based on the decision result of S2, the control unit controls the drive motor and the drive assembly to perform corresponding switching operations, the switching operations including: Switch from high-speed movement mode to high passability mode; Switch from high passability mode to high speed movement mode.

[0011] Preferably, in step S3, the process of switching from high-speed mobility mode to high passability mode specifically includes: A1. Control the electromagnetic lock in the fixed groove to release the lock on the auxiliary wheel; A2. Control the drive motor to drive the auxiliary leg to rotate downwards until the auxiliary wheel stably contacts the ground; A3. Adjust the attitude of the connecting rod through the drive component to make the body rise smoothly and ensure stability during the center of gravity transfer process; A4. The driving command of the drive wheel is changed from providing direct forward thrust to driving the auxiliary leg to swing through forward and reverse rotation.

[0012] Preferably, in step S3, the process of switching from high passability mode to high-speed mobility mode specifically includes: B1. Control the driving wheel to stop swinging, and drive the auxiliary leg to swing back, lifting the auxiliary wheel off the ground; B2. Control the drive motor to drive the auxiliary leg to rotate upward, so that the auxiliary wheel aligns with and enters the fixed groove; B3. Control the electromagnetic lock to lock the auxiliary wheel in the fixed groove.

[0013] Preferably, in step S2, the control unit automatically determines and triggers the switching between the high passability mode and the high-speed movement mode using a preset switching decision algorithm. The expression of the switching decision algorithm is:

[0014] in, Indicates the switching decision signal; This represents the terrain switching function; This represents an estimate of terrain complexity. This represents the robot's state vector; Represents the stability evaluation function; Represents the task requirement vector; This represents the task compliance function; This represents the weighting coefficient used to adjust stability requirements and task requirements; The switching hysteresis threshold is represented by S. The preset threshold is compared to generate the final switching command and sent to the driver component for execution.

[0015] Preferably, the control unit calculates the center of gravity trajectory of the fuselage in real time. Before mode switching, the control unit calculates the center of gravity trajectory of the fuselage in real time and determines whether its zero torque point is within the stable region formed by the support points. If not, the zero torque point is adjusted to fall into the stable region by adjusting the connecting seat to ensure the stability of the mode switching process.

[0016] The technical effects and advantages of this invention are as follows: 1. Compared with existing technologies, this wheeled robot's leg extension mechanism and lightweight design method integrates the auxiliary wheel, auxiliary leg, and drive motor into a connecting base, and innovatively incorporates a fixing slot with an electromagnetic lock on the robot body, forming a compact "extension-retraction" unit. Combined with a switching decision algorithm based on terrain complexity, robot state, and task requirements, the control unit can autonomously and quickly control the drive motor and electromagnetic lock to complete the extension and retraction locking of the auxiliary wheel. This enables the robot to achieve seamless and smooth transitions between high-speed movement mode and high-accessibility mode, overcoming the shortcomings of traditional solutions such as slow switching and stiff movements.

[0017] 2. Compared with existing technologies, the leg extension mechanism and lightweight design method of this wheeled robot adopts a diagonally arranged double-link structure, supplemented by a clever fulcrum design on the connecting seat, which expands the support polygon. More importantly, the control unit can calculate the center of gravity movement trajectory and zero-torque point in real time, and actively adjust the attitude of the connecting seat before mode switching to ensure that the zero-torque point always falls within the stable region.

[0018] 3. Compared with existing technologies, the leg extension mechanism and lightweight design method of this wheeled robot achieves "invisibility" and compactness of the structure in wheel mode by designing the auxiliary wheel to swing around the axis and be stored in the fixed groove of the body. At the same time, key components such as connecting rods are made of lightweight and high-strength composite materials, which reduces the weight and rotational inertia of the mechanism while ensuring the integrity of dual-mode functions, laying the foundation for the robot's flexible movement and low-energy operation.

[0019] 4. Compared with existing technologies, the drive motor of the leg extension mechanism and lightweight design method of this wheeled robot plays different roles in two modes: in wheel mode, it drives the active wheel to rotate; in leg mode, it drives the auxiliary leg to swing through forward and reverse rotation. This "one machine, two uses" design avoids the redundancy and complexity of setting up independent drive sources for the two modes, simplifies the transmission chain, and reduces manufacturing costs and control system complexity. Attached Figure Description

[0020] Figure 1 This is a schematic diagram of the overall three-dimensional structure of the present invention.

[0021] Figure 2 This is a side view of the overall three-dimensional structure of the present invention.

[0022] Figure 3 This is a schematic diagram of a partial three-dimensional structure of the mechanical leg of the present invention.

[0023] Figure 4 This is a schematic diagram of the mechanical leg of the present invention exploding.

[0024] Figure 5 This is a flowchart of the method of the present invention.

[0025] Figure 6 This is a flowchart illustrating the switching from high-speed movement mode to high passability mode in this invention.

[0026] Figure 7 This is a flowchart illustrating the switching from high passability mode to high-speed movement mode in this invention.

[0027] The attached figures are labeled as follows: 1. Body; 2. First rotating shaft; 3. Connecting rod; 4. Second rotating shaft; 5. Connecting seat; 6. Drive wheel; 7. Drive motor; 8. Auxiliary leg; 9. Auxiliary wheel; 10. Fixing groove; 11. Control unit; 12. Drive assembly; 101. Electromagnetic lock. Detailed Implementation

[0028] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0029] Example 1 As attached Figures 1 to 7 The shown wheeled robot leg extension mechanism includes a body 1. A first rotating shaft 2 is provided on the outer wall of the body 1. A connecting rod 3 is provided on one side of the first rotating shaft 2. A second rotating shaft 4 is provided on one side of the connecting rod 3. A connecting seat 5 is provided on one side of the second rotating shaft 4. A drive wheel 6 and a drive motor 7 are provided on the connecting seat 5. The drive motor 7 is configured to drive the drive wheel 6 to rotate or drive the auxiliary leg 8 to swing around the second rotating shaft 4. An auxiliary wheel 9 is provided at the bottom of the auxiliary leg 8. A fixing groove 10 is provided on the outer wall of the body 1. When the auxiliary leg 8 swings upward, the auxiliary wheel 9 can be stored and locked in the fixing groove 10.

[0030] The body 1 is equipped with a control unit 11 inside, and a drive assembly 12 is provided at the bottom of the body 1; The connection point between the auxiliary leg 8 and the connecting seat 5 is located on one side of the axis of the driving wheel 6, so that when the auxiliary leg 8 rotates, the grounding point of the auxiliary wheel 9 is located outside the grounding point of the driving wheel 6. The connecting rod 3 is provided in two sets, and the two sets of connecting rod 3 are arranged obliquely along the outer wall of the body 1 in a vertical direction. The connecting rod 3 is made of lightweight high-strength composite material. An electromagnetic lock 101 is provided inside the fixed groove 10. The auxiliary wheel 9 is locked by the electromagnetic lock 101 after it moves into the fixed groove 10 through the folding movement of the auxiliary leg 8.

[0031] Specifically, the entire mechanism can be viewed as a multi-layered linkage system, with the following connection relationships: The fuselage 1 is the base and support platform of the entire mechanism. Its outer wall is connected to one end of the connecting rod 3 through the first rotating shaft 2. The first rotating shaft 2 is installed in the bearing seat hole of the side wall of the fuselage 1 through two high-precision deep groove ball bearings or needle roller bearings. The outer ring of the bearing is interference-fitted with the bearing seat hole of the fuselage 1, and the inner ring of the bearing is clearance-fitted or light transition-fitted with the first rotating shaft 2 to ensure that the first rotating shaft 2 can rotate freely relative to the fuselage 1. The bearing end cover is installed on the outside of the bearing for dust prevention and sealing. This connection method constitutes a standard rotating pair, allowing the entire leg mechanism to rotate around the axis on the side wall of the fuselage 1 starting from the first rotating shaft 2. This is the basis for realizing the lifting and attitude adjustment of the fuselage 1. The connecting rod 3 is made of aluminum alloy, which provides both lightweight and high structural strength. One end of the connecting rod 3 is connected to the first rotating shaft 2 via a spherical bearing or a bushed pin. Specifically, a connecting block can be fixed on the first rotating shaft 2, and the connecting rod 3 is hinged to the connecting block via a pin. Using a spherical bearing can better accommodate the slight wobble that may occur during the movement of the mechanism. This connection transmits the rotational joint of the body 1 to the connecting rod 3, allowing the connecting rod 3 to swing around the axis of the first rotating shaft 2. The other end of the connecting rod 3 is also hinged to the second rotating shaft 4 via a spherical bearing or a pin. The second rotating shaft 4 itself is also mounted in the corresponding mounting hole of the connecting seat 5 via a bearing. This connection forms a "floating" rotational joint, transmitting the movement of the connecting rod 3 to the connecting seat 5. The second rotating shaft 4 is mounted on the connecting seat 5 via a bearing, allowing it to rotate relative to the connecting seat 5. This connection point is the core pivot of the swinging auxiliary leg 8. The drive motor 7 is typically a high-performance brushless DC servo motor, which is directly fixed to the main structure of the connecting seat 5 via its flange and fastening bolts. The output shaft of the drive motor 7 passes through the wall of the connecting seat 5, and the drive wheel 6 is directly mounted on the output shaft of the drive motor 7 via a key connection or interference fit. This means that the drive motor 7 can directly drive the drive wheel 6 to rotate. The upper end of the auxiliary leg 8 is rigidly fixed to the second rotating shaft 4 by fasteners or welding.

[0032] Therefore, when the second pivot 4 rotates, it will cause the auxiliary leg 8 to swing around the axis of the second pivot 4. It should be noted that this connection point is located on one side of the axis of the driving wheel 6, meaning that the fixing point of the auxiliary leg 8 is not concentric with the driving wheel 6, thus forming an eccentric swing arm structure. The auxiliary wheel 9 is mounted on the bottom end of the auxiliary leg 8 via a simple axle and bearing. This axle only serves a supporting function; the auxiliary wheel 9 can rotate freely and has no driving force itself. As a driven wheel, the auxiliary wheel 9 provides an additional support point in the footed mode. The fixing groove 10 is a recess directly machined into the outer shell of the machine body 1, or it is an independent component whose shape matches the outer edge of the auxiliary wheel 9, and is fixed to the outer wall of the machine body 1 by bolts. The lock body of the electromagnetic lock 101 is implemented by an electromagnet, which is embedded in the side wall or bottom of the fixing groove 10. When the auxiliary wheel 9 is retracted into the fixing groove 10, the energized locking tongue of the electromagnetic lock 101 will extend and cooperate with the groove on the axle or hub of the auxiliary wheel 9 to mechanically lock it. The control unit 11, consisting of one or more circuit boards, is fixed inside the body 1 by a bracket. The drive assembly 12 is typically a powerful servo motor or linear motor, with its housing fixed inside the body 1. Its output servo disc or push rod is connected to the first rotating shaft 2 or a rocker arm fixed thereto, used to drive the first rotating shaft 2 to rotate, thereby controlling the overall attitude of the linkage 3 mechanism. The above components, connected under the unified command of the control unit 11, achieve the following functions: High-speed movement mode: The drive motor 7 receives a command from the control unit 11 and drives the auxiliary leg 8 to rotate upward around the second pivot 4 until the auxiliary wheel 9 enters the fixed groove 10. Subsequently, the control unit 11 sends a signal to the electromagnetic lock 101 to engage it, completing the mechanical locking. This process ensures that the auxiliary wheel 9 will not accidentally come off due to vibration during high-speed movement. The control unit 11 sends a command to the drive motor 7, which drives the active wheel 6 to rotate continuously in one direction. The robot rolls forward at high speed like a traditional wheeled robot. At the same time, the drive assembly 12 can slightly adjust the angle of the linkage 3 mechanism by driving the first pivot 2, thereby fine-tuning the pitch attitude of the body 1 to adapt to gentle slopes and other road surfaces. High-accessibility mode: Control unit 11 first de-energizes and unlocks electromagnetic lock 101. Then, drive motor 7 drives auxiliary leg 8 to swing downwards until auxiliary wheel 9 stably contacts the ground. Simultaneously, drive assembly 12 actuates, smoothly lifting body 1 to a predetermined height via linkage 3. Drive motor 7 no longer rotates continuously, but performs precise forward and reverse rotations based on gait algorithms generated by control unit 11, such as alternating triangular gait. Since the drive shaft of auxiliary leg 8 and drive wheel 6 is eccentrically connected, the forward and reverse rotation of drive motor 7 is converted into the back-and-forth swinging of auxiliary leg 8, realizing foot-like stepping movements. The design of auxiliary wheel 9's grounding point being located outside the grounding point of drive wheel 6 expands the robot's support polygon in this mode, significantly enhancing stability. The control unit 11 continuously processes data from onboard sensors such as cameras, LiDAR, and IMU. Through a switching decision algorithm, it calculates terrain complexity in real time to assess robot stability and task compliance. When the comprehensive decision signal exceeds a threshold, a mode switching command is triggered. Before the switching action is executed, the control unit 11 calculates the zero-moment point in real time based on the robot's current state vector. If it predicts that the zero-moment point will move out of the stable region during the switching process, the control unit 11 first fine-tunes the attitude of the connecting seat 5 through the drive component 12 to ensure that the center of gravity projection always falls within the supporting polygon, thus ensuring the dynamic stability of the switching action.

[0033] A lightweight design method for wheeled robots includes the following steps: S1. Define the two operating modes of the robot: In high-speed movement mode, the auxiliary wheel 9 is stored and locked in the fixed groove 10, and the driving wheel 6 acts as the main driving wheel and rolls forward in contact with the ground. In the high passability mode, the auxiliary wheel 9 rotates downward and unfolds to contact the ground and lifts the body 1. The drive motor 7 drives the auxiliary leg 8 to swing back and forth to realize the foot-like stepping movement. S2. During operation, the control unit 11 continuously collects and analyzes road surface information ahead, and calculates the required operating mode based on a preset switching decision algorithm. S3. Based on the decision result of S2, the control unit 11 controls the drive motor 7 and the drive assembly 12 to perform corresponding switching operations, the switching operations including: Switch from high-speed movement mode to high passability mode; Switch from high passability mode to high speed movement mode.

[0034] Specifically, the robot acquires terrain point cloud data in real time through vision sensors and LiDAR integrated into the chassis 1, and uses a built-in processor to calculate terrain undulation and obstacle density to quantify the terrain complexity estimate. Simultaneously, it reads the robot's state vector in real time, including chassis tilt angle and joint torques. Based on this real-time data, the control unit 11 calls a preset switching decision algorithm for calculation. The core principle of this algorithm is to map the terrain complexity through a nonlinear switching function, then linearly combine it with a weighted stability evaluation function and a task compliance function, and finally subtract a preset hysteresis threshold to avoid frequent mode oscillations. This calculation process ultimately generates a clear switching decision signal. When the signal value exceeds a critical point, the control unit 11 automatically generates a switching command and sends it to the drive component 12 and drive motor 7 to execute the corresponding mode switching operation. This automatic switching mechanism based on multi-sensor information fusion and algorithmic decision-making enables the robot to intelligently adapt to environmental changes, autonomously selecting between high-speed movement and high-accessibility modes without human intervention, thereby significantly improving the robot's environmental adaptability and operational efficiency.

[0035] In a preferred embodiment, step S3 specifically includes the process of switching from high-speed mobility mode to high passability mode: A1. Control the electromagnetic lock 101 in the fixed groove 10 to release the lock on the auxiliary wheel 9; A2. Control the drive motor 7 to drive the auxiliary leg 8 to rotate downwards until the auxiliary wheel 9 stably contacts the ground; A3. The attitude of the connecting rod 3 is adjusted by the drive component 12 to make the body 1 rise smoothly and ensure stability during the center of gravity transfer process; A4. The driving command of the drive wheel 6 is changed from providing direct forward thrust to driving the auxiliary leg 8 to swing through forward and reverse rotation; Specifically, the control unit 11 first sends a power-off command to the electromagnetic lock 101 in the fixing slot 10, causing its locking tongue to retract and releasing the mechanical lock on the auxiliary wheel 9. Next, the control unit 11 sends a command to the drive motor 7, switching it from a high-speed rotation state of the drive wheel 6 to a precise position control mode, driving the auxiliary leg 8 to rotate downwards around the second rotating shaft 4. During this process, the encoder built into the drive motor 7 provides real-time feedback on the angle of the auxiliary leg 8, ensuring that the auxiliary wheel 9 descends smoothly at a controllable speed until it stably contacts the ground. Subsequently, the control unit 11 activates the drive assembly 12, which drives the first rotating shaft 2 to rotate, causing the connected linkage 3 to move, thereby actively adjusting the height and pitch of the connecting seat 5 and even the entire fuselage 1. This active adjustment ensures stability during the transfer of the center of gravity from the drive wheel 6 to the auxiliary wheel 9, effectively preventing the fuselage from swaying or tipping over. Once the auxiliary wheel 9 is fully grounded and the robot's posture is stable, the control unit 11 will switch the instruction logic sent to the drive motor 7, changing from providing continuous forward thrust to receiving forward and reverse pulse signals generated based on the gait algorithm. This causes the drive motor 7 to drive the auxiliary leg 8, which is eccentrically connected to it, to swing back and forth in a manner that mimics biological gait through the forward and reverse rotation of its output shaft. At this point, the robot has fully entered the high passability mode.

[0036] In a preferred embodiment, step S3 specifically includes the process of switching from high passability mode to high-speed mobility mode: B1. Control the active wheel 6 to stop swinging, and drive the auxiliary leg 8 to swing back, lifting the auxiliary wheel 9 off the ground; B2. Control the drive motor 7 to drive the auxiliary leg 8 to rotate upward, so that the auxiliary wheel 9 is aligned and enters the fixed groove 10; B3. Control the electromagnetic lock 101 to lock the auxiliary wheel 9 into the fixed groove 10; Specifically, the control unit 11 first sends a command to the drive motor 7 to stop executing the gait swing program and drive the auxiliary leg 8 to swing back a specific angle downwards from the body 1. This action uses the connecting rod 3 to lift the auxiliary wheel 9 off the ground, thereby releasing its support from the ground. Subsequently, the control unit 11 controls the drive motor 7 to switch to a precise angle control mode, driving the auxiliary leg 8 to rotate upwards around the second pivot 4. During this process, through the guide structure on the side wall of the body 1 or position-based closed-loop control, it is ensured that the axle of the auxiliary wheel 9 is precisely aligned with the entrance of the fixing slot 10 and smoothly enters it. When the sensor confirms that the auxiliary wheel 9 has been fully retracted, the control unit 11 immediately sends an energizing signal to the electromagnetic lock 101 in the fixing slot 10, causing its locking tongue to extend and form a mechanical interlock with the hub or axle of the auxiliary wheel 9, thereby firmly locking the auxiliary wheel 9 in the retracted position.

[0037] In a preferred embodiment, in step S2, the control unit 11 automatically determines and triggers the switching between the high-passability mode and the high-speed movement mode using a preset switching decision algorithm. The expression of the switching decision algorithm is:

[0038] in, Indicates the switching decision signal; This represents the terrain switching function; This represents an estimate of terrain complexity. This represents the robot's state vector; Represents the stability evaluation function; Represents the task requirement vector; This represents the task compliance function; This represents the weighting coefficient used to adjust stability requirements and task requirements; The switching hysteresis threshold is represented by S. The threshold is compared with the preset threshold to generate the final switching command, which is then sent to the driver component 12 for execution. The control unit 11 continuously collects environmental and self-state data through an onboard depth camera and inertial measurement unit. The terrain complexity estimate is quantified by the surface undulation variance calculated from point cloud data and the obstacle density. The robot state vector includes real-time parameters such as body tilt angle, joint torque, and motion velocity. The processor built into the control unit 11 periodically executes the algorithm. First, the terrain complexity estimate is input into a pre-calibrated nonlinear terrain switching function for mapping and amplification, aiming to highlight the switching requirements for complex terrains. Simultaneously, the stability evaluation function and the task compliance function are calculated in parallel. The stability evaluation function is calculated based on the current robot attitude angular velocity and the degree of deviation of the zero torque point from the stable region. The task compliance function evaluates the task execution efficiency of the current mode based on factors such as the curvature of the preset path and obstacles. Then, the output values ​​of these two functions are multiplied by configurable weight coefficients, summed, multiplied by the output of the terrain switching function, and finally subtracted by a preset switching hysteresis threshold.

[0039] In a preferred embodiment, the control unit 11 calculates the center of gravity movement trajectory of the fuselage 1 in real time. Before mode switching, the control unit 11 calculates the center of gravity movement trajectory of the fuselage 1 in real time and determines whether its zero torque point is within the stable region formed by the support points. If not, the zero torque point is adjusted by the connecting seat 5 to make it fall into the stable region, so as to ensure the stability of the mode switching process.

[0040] Specifically, the control unit 11 calculates the three-dimensional motion trajectory of the center of gravity of the fuselage 1 in real time by solving the data from the inertial measurement unit inside the fuselage 1 and combining it with the known geometric parameters of the connecting rod 3 and the auxiliary leg 8. At the same time, based on the current ground contact point positions of the auxiliary wheel 9 and the driving wheel 6, it calculates a support polygonal stability domain composed of these support points. The core task of the control unit 11 is to continuously determine whether the projection of the zero-moment point calculated based on the center of gravity trajectory and acceleration falls within this stability domain. Before executing the mode switch, the control unit 11 performs a forward calculation. If it predicts that the zero-moment point will cross the boundary of the stability domain during the switching action, it will postpone the issuance of the switching command and prioritize sending an adjustment command to the drive component 12. The drive component 12 adjusts the spatial attitude of the connecting seat 5 by precisely driving the first rotating shaft 2 to rotate, thereby actively changing the projection position of the center of gravity. This adjustment continues until the prediction shows that the zero-moment point can completely fall within the stability domain.

[0041] The above describes the working principle of the leg extension mechanism and lightweight design method of this wheeled robot.

Claims

1. A leg extension mechanism for a wheeled robot, comprising a body (1), characterized in that: A first rotating shaft (2) is provided on the outer wall of the body (1). A connecting rod (3) is provided on one side of the first rotating shaft (2). A second rotating shaft (4) is provided on one side of the connecting rod (3). A connecting seat (5) is provided on one side of the second rotating shaft (4). An active wheel (6) and a drive motor (7) are provided on the connecting seat (5). The drive motor (7) is configured to drive the active wheel (6) to rotate or drive the auxiliary leg (8) to swing around the second rotating shaft (4). An auxiliary wheel (9) is provided at the bottom of the auxiliary leg (8). A fixing groove (10) is provided on the outer wall of the body (1). When the auxiliary leg (8) swings upward, the auxiliary wheel (9) can be stored and locked in the fixing groove (10).

2. The leg extension mechanism of the wheeled robot according to claim 1, characterized in that: The body (1) is equipped with a control unit (11) inside and a drive assembly (12) is provided at the bottom of the body (1).

3. The leg extension mechanism of the wheeled robot according to claim 1, characterized in that: The connection point between the auxiliary leg (8) and the connecting seat (5) is located on one side of the axis of the driving wheel (6), so that when the auxiliary leg (8) rotates, the grounding point of the auxiliary wheel (9) is located outside the grounding point of the driving wheel (6).

4. The leg extension mechanism of the wheeled robot according to claim 1, characterized in that: The connecting rod (3) is provided in two sets, and the two sets of connecting rods (3) are arranged obliquely along the outer wall of the body (1) in a vertical direction. The connecting rod (3) is made of lightweight high-strength composite material.

5. The leg extension mechanism for a wheeled robot according to claim 1, characterized in that: An electromagnetic lock (101) is provided inside the fixed groove (10). The auxiliary wheel (9) is locked by the electromagnetic lock (101) after the auxiliary leg (8) folds and moves toward the fixed groove (10).

6. A lightweight design method for wheeled robots, applicable to the leg extension mechanism of wheeled robots according to any one of claims 1-5, characterized in that: Includes the following steps: S1. Define the two operating modes of the robot: In high-speed movement mode, the auxiliary wheel (9) is stored and locked in the fixed groove (10), and the driving wheel (6) acts as the main driving wheel and rolls forward in contact with the ground. In the high passability mode, the auxiliary wheel (9) rotates downward and unfolds to contact the ground and lifts the body (1). The drive motor (7) drives the auxiliary leg (8) to swing back and forth to achieve foot-like stepping movement. S2. During operation, the control unit (11) continuously collects and analyzes the road surface information ahead, and calculates the current required operating mode based on the preset switching decision algorithm. S3. Based on the decision result of S2, the control unit (11) controls the drive motor (7) and the drive assembly (12) to perform corresponding switching operations, the switching operations including: Switch from high-speed movement mode to high passability mode; Switch from high passability mode to high speed movement mode.

7. The lightweight design method for wheeled robots according to claim 6, characterized in that: In step S3, the process of switching from high-speed mobility mode to high passability mode specifically includes: A1. Control the electromagnetic lock (101) in the fixed groove (10) to release the lock on the auxiliary wheel (9); A2. Control the drive motor (7) to drive the auxiliary leg (8) to rotate downward until the auxiliary wheel (9) stably contacts the ground; A3. Adjust the attitude of the connecting rod (3) through the drive component (12) to make the fuselage (1) rise smoothly and ensure stability during the center of gravity transfer process; A4. The driving command of the drive wheel (6) is changed from providing direct forward thrust to driving the auxiliary leg (8) to swing by rotating in both directions.

8. The lightweight design method for wheeled legged robots according to claim 6, characterized in that: In step S3, the process of switching from high passability mode to high-speed mobility mode specifically includes: B1. Control the active wheel (6) to stop swinging, and drive the auxiliary leg (8) to swing back, thereby lifting the auxiliary wheel (9) off the ground; B2. Control the drive motor (7) to drive the auxiliary leg (8) to rotate upward, so that the auxiliary wheel (9) is aligned and enters the fixed groove (10). B3. Control the electromagnetic lock (101) to lock the auxiliary wheel (9) in the fixed groove (10).

9. The lightweight design method for wheeled legged robots according to claim 6, characterized in that: In step S2, the control unit (11) automatically determines and triggers the switching between the high passability mode and the high-speed movement mode using a preset switching decision algorithm. The expression of the switching decision algorithm is: in, Indicates the switching decision signal; This represents the terrain switching function; This represents an estimate of terrain complexity. This represents the robot's state vector; Represents the stability evaluation function; Represents the task requirement vector; This represents the task compliance function; This represents the weighting coefficient used to adjust stability requirements and task requirements; The switching hysteresis threshold is represented by S. The preset threshold is compared with S to generate the final switching command and send it to the driver component (12) for execution.

10. The lightweight design method for wheeled legged robots according to claim 6, characterized in that: The control unit (11) calculates the center of gravity trajectory of the fuselage (1) in real time. Before the mode switch, the control unit (11) calculates the center of gravity trajectory of the fuselage (1) in real time and determines whether its zero torque point is within the stable domain formed by the support point. If not, the zero torque point is made to fall into the stable domain by adjusting the connecting seat (5) to ensure the stability of the mode switch process.

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