208 results about "Biped robot" patented technology

The invention relates to a biped robot complex terrain self-adaptive gait planning method and a biped robot, and belongs to the technical field of robotics.The biped robot complex terrain self-adaptive gait planning method comprises the steps that a fractional order PID controller is constructed, and the fractional order PID controller comprises a multi-sensor network module, a self-adaptive module and a fractional order calculus control module; constructing a reinforcement learning model for biped robot gait planning, setting a state, an action, a decision and a reinforcement learning reward function of reinforcement learning, performing continuous iteration and optimization adjustment on the reinforcement learning model by using a strategy gradient method, updating strategy parameters, and outputting control parameters of the biped robot; and performing decision fusion on control parameters output by the fractional order PID controller and the reinforcement learning model through a comprehensive loss function to obtain globally optimal biped robot control parameters. According to the method, more accurate gait planning can be provided for the biped robot in complex terrains, and better walking flexibility and adaptability are achieved.

The invention discloses a compact humanoid robot leg structure and a robot, and belongs to the technical field of humanoid robots. In order to solve the problems that an existing humanoid robot leg is complex and redundant in structure, low in structure and form bionic degree and the like, the humanoid robot leg which is small in size, modularized, simple and compact in structure and high in structure bionic degree is provided, and the manufacturing difficulty, cost, size and total structure weight of the robot leg are reduced. The leg structure comprises a hip joint module, a thigh module, a knee joint module, a shank module and an ankle-sole module which are sequentially connected, and three-degree-of-freedom movement of a bionic hip joint, three-degree-of-freedom movement of a knee joint and two-degree-of-freedom movement of an ankle joint can be achieved. The method can be used for humanoid robots and biped robots.

The invention belongs to the technical field of robots, and discloses a biped robot state estimation method based on multi-sensor information, and the method comprises the steps: obtaining the data of an inertial measurement unit, a joint encoder and a joint sensor on a biped robot; a self-adaptive threshold contact state detection algorithm based on current sensing information is designed, and the contact state of the sole and the environment is judged in real time; determining a supporting phase of the robot according to the contact state, and applying a dynamic reference system conversion mechanism of supporting phase perception; constructing a state estimator based on invariant extended Kalman filter IEKF, defining a state vector including the posture, position and speed of the robot, performing state prediction by using IMU data, and performing state updating in combination with contact state information, kinematics information and the like; and outputting accurately estimated robot state information. According to the method, the adaptive contact detection and the IEKF are introduced, so that the state estimation precision and robustness of the biped robot in the dynamic walking process are effectively improved.

The invention belongs to the related technical field of mobile robots, and discloses a rolling-walking composite motion control method and device for a double-wheel-foot robot, and the method comprises the steps: (1) simplifying the rolling motion of wheels of the double-wheel-foot robot into the sliding motion of a sliding block; (2) constructing a system kinetic equation of the double-wheel-foot robot based on the simplified kinetic model; constructing a constraint equation based on the contact state of the two legs and the ground; discretizing the system kinetic equation, the cost function and the constraint equation, and converting model prediction control problems corresponding to the system kinetic equation, the cost function and the constraint equation into nonlinear problems for numerical solution so as to complete leg motion planning; (3) calculating the rotation speed of the wheel based on the leg motion planning result; and (4) based on the rotation speed of the wheels and the leg motion planning result, a whole-body control algorithm is adopted to calculate and obtain moment instructions of leg joints and the wheels. According to the invention, the state space dimension is reduced, and the wheel-ground contact constraint is simplified.

The biped robot comprises a main body connecting part and leg parts arranged on the two sides of the main body connecting part, and each leg part comprises a thigh part, a shank part, a sole assembly and a connecting rod assembly used for connection which are sequentially connected; the thigh part comprises a thigh rotating joint, a thigh lifting linear joint, a shank bending linear joint and a thigh supporting plate, the thigh lifting linear joint and the shank bending linear joint are linear actuators and are oppositely arranged, and the two ends of the thigh lifting linear joint and the two ends of the shank bending linear joint are rotationally installed; the shank part comprises an ankle linear joint and a shank supporting plate, the upper end of the ankle linear joint is rotatably connected with the shank supporting plate, and the lower end of the ankle linear joint is connected with the sole assembly. The method has the beneficial effects that the load capacity of the biped robot is improved, and the requirements of the biped robot for large load, high response speed and high precision can be met.

The present description relates to motion planning for a biped robot. According to an example of the present disclosure, a motion planning method for a biped robot may comprise: acquiring a discrete map with terrain information that corresponds to an area to be walked, determining terrain points in the discrete map that indicate that a biped robot is allowed to pass through, and generating a preliminary foothold sequence on the basis of the terrain points; generating a preliminary motion trajectory of the biped robot on the basis of the discrete map; and on the basis of a preset objective function and on the basis of the preliminary motion trajectory and a kinematic model of the biped robot, optimizing the preliminary foothold sequence, so as to generate a target foothold sequence. By means of determining, on the basis of gradient information of the ground level in a discrete map, whether a position allows a biped robot to pass through or whether the position can be used as a foothold of the biped robot, parameter optimization is performed on the foothold to obtain a target foothold sequence, such that the biped robot is enabled to complete a crossing task in view of terrain characteristics.

According to the biped robot foot structure capable of adapting to the complex road surface, the whole foot structure is designed through modular decomposition, when a user walks on the wet and slippery flat ground, the foot obtains information of foot sole sensors on the front foot sole and the rear foot sole in real time, and the virtual constraint structure is actively controlled through an electric cylinder; stress of a front longitudinal arch sole joint is reduced, meanwhile, the ground pressure transmission direction of a foot structure is improved, the ground pressure is kept in a friction cone as much as possible, and therefore the robot is prevented from slipping; when the robot walks on an uneven road surface, the electric cylinder actively controls the ground contact angle of the front foot sole, and the spring guide rod of the rear foot sole is assisted, so that active and passive self-adaptive adjustment of the foot of the robot to the ground is realized. The electric cylinder is used as a virtual constraint structure for active control, and the spring telescopic rod structure of the rear sole imitating ligament is combined, so that active and passive self-adaption of the feet of the robot to different complex road surfaces is realized, and the adaptability of the biped robot to the complex road surfaces is improved.

The parallel biped robot with the waist structure is characterized by comprising a parallel double-leg structure, the waist structure and an upper body structure which are arranged from bottom to top and can move independently; the parallel double-leg structure comprises a leg structure cross beam, the two ends of the leg structure cross beam are downwards connected with leg structures, and the upper portion of the leg structure cross beam is fixedly connected with the waist structure; the waist structure is a six-degree-of-freedom Stewart mechanism, a lower platform of the waist structure is rigidly connected with a cross beam of the leg structure, an upper platform of the waist structure is rigidly connected with the upper body structure, and six telescopic rods are connected between the upper platform and the lower platform; the invention further discloses a walking method of the robot, through introduction of the six-degree-of-freedom waist structure, the robot can adjust the position and posture of the upper body in real time in the walking process, active compensation of mass center deviation is achieved, and compared with a traditional serial connection type waist mass center adjusting range is larger, the corresponding speed is higher, and the robot can walk more stably. And the advancing stability is obviously improved.

The invention provides a robot sensing terrain recognition gait control method and system, a medium and equipment, and belongs to the technical field of robot sensing. The method comprises the following steps: acquiring pitch angle data and plantar force data of the biped robot on the basis of optimal plantar force; inputting the pitch angle data and the plantar force data into a trained KNN model, and identifying the current walking terrain of the robot to obtain a terrain identification result; the training process of the KNN model comprises the steps that the biped robot is driven to pass through a rugged terrain and a flat terrain in a fixed stride frequency gait mode, pitch angle sample data and plantar force sample data passing through different terrains are collected and input into the KNN model, and the KNN model is used for conducting terrain classification; and the robot controller receives a terrain recognition result, and adjusts the stride frequency and the gait of the robot according to a preset gait control strategy based on the result. According to the method, an additional sensor does not need to be added to the robot, and the terrain can be identified only through state feedback of the robot.

The invention discloses a multi-purpose humanoid biped robot based on a three-point visual recognition system. The multi-purpose humanoid biped robot comprises an upper body unit; the head unit is located at the upper end of the upper body unit; the arm units are located on the left and right sides of the upper body unit; the leg units are integrated on the left side and the right side below the upper body unit through hip joint units; a visual sensor is integrated in the head unit, and the shooting angle of the visual sensor is adjusted through a head movement module integrated in the head unit. The head of the biped robot has two degrees of freedom, so that the head can pitch and rotate, meanwhile, the visual sensor is carried, information of the surrounding environment can be collected in real time, and main information input is provided for the robot.

The invention discloses a line drive type biped robot leg structure which comprises a thigh support, a knee joint motor is arranged at the lower end of the thigh support, a shank support is connected to an output shaft of the knee joint motor, a foot assembly is movably connected to the lower end of the shank support and comprises a foot fixing piece, and a heel is connected to the rear portion of the foot fixing piece. The heel is connected with a line driving structure, the line driving structure comprises a first ankle joint motor, a second ankle joint motor, a first driving line wheel, a second driving line wheel, a first ankle joint line wheel and a second ankle joint line wheel, and a first transmission line is arranged between the first driving line wheel and the first ankle joint line wheel; a second transmission line is arranged between the second driving line wheel and the second ankle joint line wheel, a first crank swing rod structure is arranged between the first ankle joint line wheel and one side of the heel, and a second crank swing rod structure is arranged between the second ankle joint line wheel and the other side of the heel. The device has the advantages of being simple in structure and good in adaptability.

The invention discloses a seven-degree-of-freedom series-parallel structure mechanical arm for a biped robot, and relates to the field of robots, the seven-degree-of-freedom series-parallel structure mechanical arm is installed on a supporting body, and the supporting body is located on an installation fixing base. Comprising a five-degree-of-freedom series arm and a two-degree-of-freedom parallel wrist structure which is located at the front end of the series arm and connected with the series arm. According to the mechanical arm with the series-parallel connection structure, the rigidity and the bearing capacity of the mechanical arm are improved, the working space is expanded to adapt to more complex operation tasks, the stability and the reliability of operation are enhanced, error accumulation is reduced, and the accuracy of overall operation is improved.

The present invention provides a whole-body compliance control method applied to a fast and stable walking biped robot, and the control method includes: obtaining a plantar stress and a plantar moment based on information of a foot force sensor to estimate an actual ZMP position of the robot; designing a centroid compliance controller based on the actual ZMP position of the robot to correct a centroid acceleration; designing a plantar position compliance controller based on a double spring-damper model according to the plantar stress to correct a foot height; designing a plantar posture compliance controller based on the plantar moment to correct a plantar posture; adding corrected centroid and foot values into an originally desired trajectory; and obtaining motor angles of various joints. In the method, the plantar position compliance controller is used to reduce the landing impact; the plantar posture compliance controller is used to ensure that the robot lands flat to prevent the robot from rollover; the centroid compliance controller is used to adjust a centroid position to prevent a robot body from bending forward and backward when the robot walks fast, thereby increasing the stability of the biped robot during fast walking.

The invention relates to the technical field of robots, and discloses an actuator, a joint module, a biped robot, a quadruped robot, a four-wheeled robot, a mechanical arm and a robot. The actuator mainly comprises a first-stage planet carrier, a first bearing, a gear ring and a supporting frame, the first-stage planet carrier enables the first bearing to be installed between a first supporting part and a second supporting part of the supporting frame so as to provide support for the first-stage planet carrier, the requirement for the size of the first bearing is reduced through the supporting mode, the outer diameter of the planet carrier does not need to be matched, and the supporting effect is good. The structure is more compact, and the weight and cost of the actuator can be reduced by reducing the size of the first bearing.

The invention discloses a biped robot knee joint self-adaptive locking device which comprises a rotary joint module, a sliding locking module and a sensing control module, the sliding locking module comprises an electromagnetic lock, a sliding sleeve, a reset spring, a locking sliding block, a linear guide rail and a connecting block, and the sliding sleeve is connected with the electromagnetic lock; the locking sliding block is installed on the sliding sleeve through the reset spring, the electromagnetic lock and the linear guide rail are fixed to the connecting block through bolts, the sliding sleeve is installed on the linear guide rail, and the sliding sleeve and the linear guide rail form a sliding pair. By means of the ingenious mechanical structure design, in combination with a gait phase recognition control method following a natural biped walking mode, rigid locking of the knee joint in a standing phase and flexible releasing of the knee joint in a swinging phase are achieved in a proper walking stage, and the locking mechanism has the advantages of being light in weight, low in power consumption and rapid in response; compared with an existing hydraulic locking scheme, the hydraulic locking device is simpler in structure, free of complex hydraulic pipelines and driving systems, smaller in overall size and lighter in mass.

The invention discloses a biped robot gait network training method. The method comprises the following steps: constructing a dual-channel deep reinforcement learning architecture; the running states of the X biped robots in the simple terrain of the simulation environment are collected; obtaining a current reward according to the current running state, merging each piece of information into a Markov decision process, and storing the information into an experience playback area; when the number of the Markov decision-making processes in the experience playback area is greater than a preset threshold value n, randomly taking a preset number of Markov decision-making processes from the Markov decision-making processes, and updating parameters of the main network and the opponent network; disturbance is carried out on main network parameters, and a human memory curve is simulated to carry out continuous adjustment on main network hyper-parameters clip; the biped robot with the stable walking duration reaching the preset duration is moved to the terrain with the higher difficulty level, and the network parameter updating process is repeated; and course learning is continuously carried out until the accumulated reward information and the stable walking duration of all the biped robots reach preset values.

The invention relates to the technical field of biped robot reinforcement, and discloses a historical action sequence-based biped robot reinforcement learning control method and system. The biped robot reinforcement learning control method is applied to reinforcement learning control equipment and specifically comprises the following steps that S101, a floating base frame is adopted to load a biped robot URDF model in an Isaac Gym simulation platform, ten active joint freedom degrees are configured, and a control interface is constructed to output a 10-dimensional motor position command vector; the motion robustness and adaptability of the biped robot in a dynamic environment are remarkably improved by constructing a Transform time sequence modeling architecture fusing a historical state-action sequence, and the historical observation and action sequence is combined with sine-cosine position coding to be input into a multi-layer Transform encoder, so that the motion robustness and adaptability of the biped robot in the dynamic environment are improved. The self-attention mechanism is used for capturing the long time sequence dependence relation of foot-ground contact force change, topographic relief and the like, and the problem of gait instability caused by limited local observation in a traditional method is solved.

The invention relates to the technical field of robot control. A humanoid robot gait generation system based on hierarchical control is characterized by comprising a multi-layer control system operating at different refresh frequencies, and the multi-layer control system comprises a high-layer gait and trajectory planning layer operating at a low frequency and used for generating a macroscopic motion instruction; the middle-layer whole-body motion optimization layer runs at medium frequency, serves as a bridge of high-layer planning and bottom-layer control and is used for converting expected plantar and trunk tracks into reference motion of all joints of the whole body; the bottom joint servo control layer runs at the highest frequency and is responsible for accurately tracking a joint-level instruction output by the whole-body motion optimization layer; the state sensing and feedback closed-loop layer is used for feeding back state information, obtained in real time, of the body state of the robot to all the layers, providing a basis for track re-planning of a high layer and providing a real-time state initial value for optimization of a middle layer; and a feedback signal is provided for servo control of a bottom layer.

The invention discloses a lower limb leg-foot structure with jumping ability and a biped robot. The lower limb leg-foot structure comprises a thigh assembly, a shank assembly and a foot assembly which are sequentially connected from top to bottom. A thigh body, a knee joint rocker arm and a shank pull rod of the thigh assembly and a shank body of the shank assembly form a four-bar mechanism. The thigh body, the knee joint driving motor and the knee joint rocker arm form a slider-crank mechanism. The four-connecting-rod mechanism and the slider-crank mechanism form a set of combined mechanism through the common knee joint rocker arm so as to drive the knee joint to rotate. According to the combined mechanism, the linear motion speed of the knee joint driving motor is amplified into the rotation angular speed of the knee joint through the variable reduction ratio amplification effect of the four connecting rods, and the lower limb of the knee joint driving motor has the explosive jumping ability under the condition of the conventional output speed.

The invention provides a humanoid robot single-leg gait transition action design and a control method thereof, and through an algorithm module of a finite-state machine and the single-leg gait transition action design, the problems of center-of-gravity shift and insufficient control precision of a biped robot during gait transition can be effectively solved. By means of the method, the gait control capacity of the robot in the complex environment is remarkably improved, especially in the single-foot supporting and single-leg jumping stage, the robot can be stably switched to the corresponding gait, and the possibility of inclination and unbalance is reduced.

The invention provides an actuator, a joint module, a mechanical arm, a biped robot, a quadruped robot, a quadruped robot, a humanoid robot and a robot. The actuator comprises a shell, a motor assembly and a speed reducer assembly, the shell comprises an outer shell part, a first extension part and an inner cylinder part, and a first containing cavity with an opening is defined; the motor assembly is composed of a rotor, a stator, a rotor adapter and a rotary supporting assembly, the rotor adapter is provided with a rotor connecting part, a second extending part and a first connecting shaft part and is connected with the rotor, the rotor and the stator are arranged in the first containing cavity, and the rotary supporting assembly is arranged between the first connecting shaft part and the inner cylinder part; an input end transmission shaft of the speed reducer assembly is connected with the first connecting shaft part and rotates along with the rotor adapter, the second extension part is close to the speed reducer assembly, and the first extension part is far away from the speed reducer assembly relative to the second extension part. According to the invention, the transmission precision of the actuator and the stability of power output are ensured while the small size and compactness of the actuator are realized.

A robot control method, and a computer-readable storage medium and a wheel-legged biped robot using the same are provided. The method includes: determining a kinetic model of the wheel-legged biped robot; determining, using the kinetic model, a sliding surface of the wheel-legged biped robot; determining, according to the sliding surface, a double power reaching law and a sliding mode control law of the wheel-legged biped robot; and controlling, according to the sliding surface, the double power reaching law and the sliding mode control law, the wheel-legged biped robot. Through the above-mentioned method, the adaptability of the wheel-legged biped robot to uncertain external disturbances can be enhanced, thereby improving its robustness to effectively maintain its balance even in the environment with complex terrain.

The invention provides a biped robot gait planning method and device for a step terrain, and belongs to the technical field of robot gait planning, the method comprises the following steps: based on a linear inverted pendulum model, respectively establishing walking modes of an upper step and a lower step of a biped robot; based on a walking mode, mapping the linear inverted pendulum model under the step terrain into a segmented virtual height linear inverted pendulum model under the plane terrain; based on a segmented virtual height linear inverted pendulum model, gait planning of the biped robot under the stepped terrain is achieved through model prediction control. According to the biped robot gait planning method and device for the step terrain, the linear inverted pendulum model with the virtual centroid height is used, the gait mode is established according to the terrain elevation information and the landing point information of the step environment, and the method and device can adapt to the irregular step terrain with the variable height and the variable length; and the gait has good terrain adaptability.

The invention discloses a leg structure of a biped robot, belongs to the technical field of humanoid robots, and solves the problem that the mass distribution of a series connection structure is too close to the tail end of a leg in the leg design on the basis of realizing two-degree-of-freedom rotation, namely left-right movement along an X axis and front-back movement along a Y axis. The movement of a human hip joint can be better simulated; the driver of the thigh part firstly drives the middleware, and then the middleware drives the driven part to move, so that relative sliding of the thighbone and the tibia and bending movement of the knee joint are simulated under the assistance of the middleware; the telescopic driving part of the shank part drives the universal joint to rotate at any angle in the telescopic process, meanwhile, the movable plate can conduct front-back pitching, left-right swinging and plane rotation, three-degree-of-freedom movement is achieved, the parallel structure is adopted, and better distribution of force and torque can be achieved.

The utility model relates to the technical field of biped humanoid robots, in particular to a biped robot lower limb structure which comprises a hip joint assembly 2, a thigh assembly 3 and a shank and foot assembly 4 which are sequentially connected, the hip joint assembly 2 comprises a left hip joint and a right hip joint which are symmetrical, and the thigh assembly 3 comprises two symmetrical thighs. The shank and foot assembly 4 comprises two sets of symmetrical shanks and feet, the left hip joint and the right hip joint are each provided with an integrated joint motor with the freedom degree in the three-dimensional direction, each thigh is provided with a knee joint motor with the freedom degree, and each shank and foot is provided with shank motors with the two freedom degrees. The lower limb structure of the biped robot has the advantages of being simple in structure, flexible to control, stable in dynamic performance and the like, can quickly respond to humanoid leg movement, and can be used in the lower limb structure of the humanoid robot through walking gait planning of the biped robot so as to promote technical development of the humanoid robot.

The invention relates to the field of humanoid robots, and provides a control method for biped robot step-by-step gait strategy fusion in order to solve the problems that a biped robot is large in training difficulty, unnatural in gait, poor in adaptability and the like. Training various different terrain categories through an imitation learning algorithm and a reinforcement learning algorithm to obtain a gait strategy model; s2, performing pairwise fusion gait strategy switching between the gait strategy models corresponding to various different terrain categories; s3, the terrain category of the current position is recognized in real time according to an information collection unit of the biped robot, a corresponding gait strategy model is obtained through a strategy execution control unit, and the biped robot is controlled to walk in the corresponding motion state; and S4, when the terrain category of the biped robot is changed, smooth transition between the two gait strategy models is achieved through gait strategy switching, and control over gait strategy fusion of the biped robot is completed.

The invention discloses a reinforcement learning biped robot gait control method based on a multilayer adaptive exploration mechanism, and belongs to the field of biped robot reinforcement learning control. The method aims at solving the problems that in existing gait control based on a near-end strategy optimization (PPO) algorithm, strategy convergence is unstable, and exploration and utilization balance is insufficient. According to the method, a multi-layer adaptive exploration mechanism is introduced on the basis of a standard PPO framework: firstly, a state-dependent standard deviation network is designed to realize adaptive noise adjustment of a space layer for dynamically controlling action disturbance intensity; secondly, constructing an entropy regularization mechanism based on advantage weighting, and realizing exploration intensity adaptive control of a direction layer; thirdly, a dynamic entropy coefficient is designed according to the uncertainty of a value function, and exploration rhythm self-adaptive adjustment of a time layer is achieved. Through the synergistic effect of three layers of mechanisms, the strategy realizes dynamic balance of exploration and convergence in different training stages, so that the stability of the training process and the strategy convergence quality are improved.

The utility model discloses a leg structure of a biped robot and a humanoid robot. The biped robot leg structure comprises a hip joint assembly, a thigh assembly, a shank assembly and a foot which are connected in sequence. The hip joint driving motor is connected with the knee joint driving motor through a connecting assembly, and the hip joint driving motor and the knee joint driving motor are coaxially arranged; the shank assembly and the thigh assembly are connected through a first ankle joint rotating motor, and the first ankle joint rotating motor serves as a knee joint rotating shaft. The first ankle joint rotating motor is located at the root of the shank assembly, and the knee joint driving motor is located at the root of the thigh assembly so as to reduce inertia of the tail ends of robot limbs. The leg structure of the biped robot is improved, inertia is made to move upwards by moving the driving motor upwards, and the flexibility and the dynamic performance of the robot are improved; the compactness of the leg structure of the biped humanoid robot is improved, the transmission angle is effectively limited, the transmission stability is improved, and the encoder and the like are convenient to maintain.

The invention discloses a biped robot control method and device, electronic equipment and a storage medium. The method comprises the steps that actual observation data at the current moment are collected through a target sensor of a biped robot body; wherein the target sensor comprises a joint encoder, an inertia measuring instrument and a plantar force sensor; predicting a state prediction value at the current moment by combining the state prediction value at the previous moment and a motion model of the biped robot; predicting predicted observation data at the current moment by using the state predicted value at the current moment based on the relationship between the observation data and the state data; correcting the state prediction value at the current moment based on the deviation between the actual observation data at the current moment and the prediction observation data to obtain a state correction value at the current moment; selecting a control parameter in a current state for the unified reinforcement learning control strategy through the correction function based on the state correction value at the current moment, and correcting the control parameter to obtain a current control parameter; and controlling the current biped robot according to the current control parameters.

The invention relates to a method and device for a biped robot to wear common sports shoes, and belongs to the technical field of robots. The method comprises the steps that a pre-planned gait track is initialized and generated; calculating the actual centroid position of the robot at each moment; a Kalman filtering algorithm is adopted to fuse multi-source data to update the normal stiffness and the friction coefficient of the sole in real time, and the rate is updated through adaptive gain adjustment parameters; adjusting a zero moment point constraint range, and generating a centroid reference position of a preset step number; establishing a sole characteristic database, training a machine learning model, inputting shoe parameters into the machine learning model, and outputting step length, step frequency and ankle joint rigidity by the machine learning model; an ankle joint target angle and a knee joint target angle are solved through inverse kinematics, and a joint motor is driven in combination with a PD control algorithm and a self-adaptive item; when the vertical acceleration of the IMU sensor is larger than a preset acceleration threshold value, the time period before grounding is judged, and a compliant mode is triggered to control the ankle joint rigidity and the torque borne by the joint.