The research on legged robots attracted much attention both from the academia and industry. Legged robots are multi-input multi-output with multiple end-e ector systems. Therefore,the mechanical design and control fra...The research on legged robots attracted much attention both from the academia and industry. Legged robots are multi-input multi-output with multiple end-e ector systems. Therefore,the mechanical design and control framework are challenging issues. This paper reviews the development of type synthesis and behavior control on legged robots; introduces the hexapod robots developed in our research group based on the proposed type synthesis method. The control framework for legged robots includes data driven layer,robot behavior layer and robot execution layer. Each layer consists several components which are explained in details. Finally,various experiments were conducted on several hexapod robots. The summarization of the type synthesis and behavior control design constructed in this paper would provide a unified platform for communications and references for future advancement for legged robots.展开更多
Unmanned systems such as legged robots require fast-motion responses for operation in complex envi-ronments.These systems therefore require explosive actuators that can provide high peak speed or high peak torque at s...Unmanned systems such as legged robots require fast-motion responses for operation in complex envi-ronments.These systems therefore require explosive actuators that can provide high peak speed or high peak torque at specific moments during dynamic motion.Although hydraulic actuators can provide a large force,they are relatively inefficient,large,and heavy.Industrial electric actuators are incapable of providing instant high power.In addition,the constant reduction ratio of the reducer makes it difficult to eliminate the tradeoff between high speed and high torque in a given system.This study proposes an explosive electric actuator and an associated control method for legged robots.First,a high-power-density variable transmission is designed to enable continuous adjustment of the output speed to torque ratio.A heat-dissipating structure based on a composite phase-change material(PCM)is used.An integral torque control method is used to achieve periodic and controllable explosive power output.Jumping experiments are conducted with typical legged robots to verify the effectiveness of the proposed actuator and control method.Single-legged,quadruped,and humanoid robots jumped to heights of 1.5,0.8,and 0.5 m,respectively.These are the highest values reported to date for legged robots powered by electric actuators.展开更多
Adaptive locomotion in different types of surfaces is of critical importance for legged robots.The knowledge of various ground substrates,especially some geological properties,plays an essential role in ensuring the l...Adaptive locomotion in different types of surfaces is of critical importance for legged robots.The knowledge of various ground substrates,especially some geological properties,plays an essential role in ensuring the legged robots'safety.In this paper,the interaction between the robots and the environments is investigated through interaction dynamics with the closed-loop system model,the compliant contact model,and the friction model,which unveil the influence of environment's geological characteristics for legged robots'locomotion.The proposed method to classify substrates is based on the interaction dynamics and the sensory-motor coordination.The foot contact forces,joint position errors,and joint motor currents,which reflect body dynamics,are measured as the sensing variables.We train and classify the features extracted from the raw data with a multilevel weighted k-Nearest Neighbor(kNN) algorithm.According to the interaction dynamics,the strategy of adaptive walking is developed by adjusting the touchdown angles and foot trajectories while lifting up and dropping down the foot.Experiments are conducted on five different substrates with quadruped robot FROG-I.The comparison with other classification methods and adaptive walking between different substrates demonstrate the effectiveness of our approach.展开更多
The stable slope-walking ability of legged robot walking in any direction on slope is analysed. The contacting angle and leaving angle of leg to the ground are presented. A method to increase the slope-walking ability...The stable slope-walking ability of legged robot walking in any direction on slope is analysed. The contacting angle and leaving angle of leg to the ground are presented. A method to increase the slope-walking ability is proposed only by changing the contacting angle and leaving angle of the leg to the ground.展开更多
The wheeled bipedal robots have great application potential in environments with a mixture of structured and unstructured terrain. However, wheeled bipedal robots have problems such as poor balance ability and low mov...The wheeled bipedal robots have great application potential in environments with a mixture of structured and unstructured terrain. However, wheeled bipedal robots have problems such as poor balance ability and low movement level on rough roads. In this paper, a novel and low-cost wheeled bipedal robot with an asymmetrical five-link mechanism is proposed, and the kinematics of the legs and the dynamics of the Wheeled Inverted Pendulum (WIP) are modeled. The primary balance controller of the wheeled bipedal robot is built based on the Linear Quadratic Regulator (LQR) and the compensation method of the virtual pitch angle adjusting the Center of Mass (CoM) position, then the whole-body hybrid torque-position control is established by combining attitude and leg controllers. The stability of the robot’s attitude control and motion is verified with simulations and prototype experiments, which confirm the robot’s ability to pass through complex terrain and resist external interference. The feasibility and reliability of the proposed control model are verified.展开更多
This paper proposes the Leg Dimensional Synergistic Optimization Strategy(LDSOS)for humanoid robotic legs based on mechanism decoupling and performance assignment.The proposed method addresses the interdependent effec...This paper proposes the Leg Dimensional Synergistic Optimization Strategy(LDSOS)for humanoid robotic legs based on mechanism decoupling and performance assignment.The proposed method addresses the interdependent effects of dimensional parameters on the local and whole mechanisms in the design of hybrid humanoid robotic legs.It sequentially optimizes the dimensional parameters of the local and whole mechanism,thereby balancing the motion performance requirements of both.Additionally,it considers the assignment of efficient performance resources between the Local Functional Workspace(LFW)and the Whole Available Workspace(WAW).To facilitate the modeling and optimization process,a local/whole Equivalent Configuration Framework(ECF)is introduced.By decoupling the hybrid mechanism into a whole mechanism and multiple local mechanisms,the ECF enhances the efficiency of design,modeling,and performance evaluation.Prototype experiments are conducted to validate the effectiveness of LDSOS.This research provides an effective configuration framework for humanoid robotic leg design,establishing a theoretical and practical foundation for future optimized designs of humanoid robotic legs and pioneering novel approaches to the design of complex hybrid humanoid robotic legs.展开更多
Heavy-duty legged robots have been regarded as one of the important developments in the field of legged robots because of their high payload-total mass ratio,terrain adaptability,and multitasking.The problems associat...Heavy-duty legged robots have been regarded as one of the important developments in the field of legged robots because of their high payload-total mass ratio,terrain adaptability,and multitasking.The problems associated with the development and use of heavy-duty legged robots have motivated researchers to conduct many important studies,covering topics related to the mechanical structure,force distribution,control strategy,energy efficiency,etc.Overall,heavy-duty legged robots have three main characteristics:greater body masses,larger body sizes,and higher payload-total mass ratios.Thus,various heavy-duty legged robots and their performances are reviewed here.This review presents the current developments with regard to heavy-duty legged robots.Also,the main characteristics of high-performance heavy-duty legged robots are determined and conclusions are drawn.Furthermore,the current research of key techniques of heavy-duty legged robots,including the mechanical structure,force distribution,control method,and power source,is described.To assess the transportation capacity of heavy-duty legged robots,performance evaluation parameters are proposed.Finally,problems that need further research are addressed.展开更多
Human tracking is an important issue for intelligent robotic control and can be used in many scenarios, such as robotic services and human-robot cooperation. Most of current human-tracking methods are targeted for mob...Human tracking is an important issue for intelligent robotic control and can be used in many scenarios, such as robotic services and human-robot cooperation. Most of current human-tracking methods are targeted for mobile/tracked robots, but few of them can be used for legged robots. Two novel human-tracking strategies, view priority strategy and distance priority strategy, are proposed specially for legged robots, which enable them to track humans in various complex terrains. View priority strategy focuses on keeping humans in its view angle arrange with priority, while its counterpart, distance priority strategy, focuses on keeping human at a reasonable distance with priority. To evaluate these strategies, two indexes（average and minimum tracking capability） are defined. With the help of these indexes, the view priority strategy shows advantages compared with distance priority strategy. The optimization is done in terms of these indexes, which let the robot has maximum tracking capability. The simulation results show that the robot can track humans with different curves like square, circular, sine and screw paths. Two novel control strategies are proposed which specially concerning legged robot characteristics to solve human tracking problems more efficiently in rescue circumstances.展开更多
This paper proposes a novel continuous footholds optimization method for legged robots to expand their walking ability on complex terrains.The algorithm can efficiently run onboard and online by using terrain percepti...This paper proposes a novel continuous footholds optimization method for legged robots to expand their walking ability on complex terrains.The algorithm can efficiently run onboard and online by using terrain perception information to protect the robot against slipping or tripping on the edge of obstacles,and to improve its stability and safety when walking on complex terrain.By relying on the depth camera installed on the robot and obtaining the terrain heightmap,the algorithm converts the discrete grid heightmap into a continuous costmap.Then,it constructs an optimization function combined with the robot’s state information to select the next footholds and generate the motion trajectory to control the robot’s locomotion.Compared with most existing footholds selection algorithms that rely on discrete enumeration search,as far as we know,the proposed algorithm is the first to use a continuous optimization method.We successfully implemented the algorithm on a hexapod robot,and verified its feasibility in a walking experiment on a complex terrain.展开更多
Terrain classification information is of great significance for legged robots to traverse various terrains.Therefore,this communication presents an online terrain classification framework for legged robots,utilizing t...Terrain classification information is of great significance for legged robots to traverse various terrains.Therefore,this communication presents an online terrain classification framework for legged robots,utilizing the acoustic signals produced during locomotion.The Mel-Frequency Cepstral Coefficient(MFCC)feature vectors are extracted from the acoustic data recorded by an on-board microphone.Then the Gaussian mixture models(GMMs)are used to classify the MFCC features into different terrain type categories.The proposed framework was validated on a quadruped robot.Overall,our investigations achieved a classification time-resolution of 1 s when the robot trotted over three kinds of terrains,thus recording a comprehensive success rate of 92.7%.展开更多
The current gait planning for legged robots is mostly based on human presets,which cannot match the flexible characteristics of natural mammals.This paper proposes a gait optimization framework for hexapod robots call...The current gait planning for legged robots is mostly based on human presets,which cannot match the flexible characteristics of natural mammals.This paper proposes a gait optimization framework for hexapod robots called Smart Gait.Smart Gait contains three modules:swing leg trajectory optimization,gait period&duty optimization,and gait sequence optimization.The full dynamics of a single leg,and the centroid dynamics of the overall robot are considered in the respective modules.The Smart Gait not only helps the robot to decrease the energy consumption when in locomotion,mostly,it enables the hexapod robot to determine its gait pattern transitions based on its current state,instead of repeating the formalistic clock-set step cycles.Our Smart Gait framework allows the hexapod robot to behave nimbly as a living animal when in 3D movements for the first time.The Smart Gait framework combines offline and online optimizations without any fussy data-driven training procedures,and it can run efficiently on board in real-time after deployment.Various experiments are carried out on the hexapod robot LittleStrong.The results show that the energy consumption is reduced by 15.9%when in locomotion.Adaptive gait patterns can be generated spontaneously both in regular and challenge environments,and when facing external interferences.展开更多
The bionic joints composed of pneumatic muscles(PMs)can simulate the motion of biological joints.However,the PMs themselves have non-linear characteristics such as hysteresis and creep,which make it difficult to achie...The bionic joints composed of pneumatic muscles(PMs)can simulate the motion of biological joints.However,the PMs themselves have non-linear characteristics such as hysteresis and creep,which make it difficult to achieve high-precision trajectory tracking control of PM-driven robots.In order to effectively suppress the adverse effects of non-linearity on control performance and improve the dynamic performance of PM-driven legged robot,this study designs a double closed-loop control structure based on neural network.First,according to the motion model of the bionic joint,a mapping model between PM contraction force and joint torque is proposed.Second,a control strategy is designed for the inner loop of PM contraction force and the outer loop of bionic joint angle.In the inner control loop,a feedforward neuron Proportional-Integral-Derivative controller is designed based on the PM three-element model.In the control outer loop,a sliding mode robust controller with local model approximation is designed by using the radial basis function neural network approximation capability.Finally,it is verified by simulation and physical experiments that the designed control strategy is suitable for humanoid motion control of antagonistic PM joints,and it can satisfy the requirements of reliability,flexibility,and bionics during human–robot collaboration.展开更多
This paper presents an effective way to support motion planning of legged mobile robots—Inverted Modelling,based on the equivalent metamorphic mechanism concept.The difference from the previous research is that we he...This paper presents an effective way to support motion planning of legged mobile robots—Inverted Modelling,based on the equivalent metamorphic mechanism concept.The difference from the previous research is that we herein invert the equivalent parallel mechanism.Assuming the leg mechanisms are hybrid links,the body of robot being considered as fixed platform,and ground as moving platform.The motion performance is transformed and measured in the body frame.Terrain and joint limits are used as input parameters to the model,resulting in the representation which is independent of terrains and particular poses in Inverted Modelling.Hence,it can universally be applied to any kind of legged robots as global motion performance framework.Several performance measurements using Inverted Modelling are presented and used in motion performance evaluation.According to the requirements of actual work like motion continuity and stability,motion planning of legged robot can be achieved using different measurements on different terrains.Two cases studies present the simulations of quadruped and hexapod robots walking on rugged roads.The results verify the correctness and effectiveness of the proposed method.展开更多
In curling competitions, the throwing strategy has a decisive influence on the outcome of the game. When robots are applied to the sport of curling, they first need to understand the various throwing strategies in cur...In curling competitions, the throwing strategy has a decisive influence on the outcome of the game. When robots are applied to the sport of curling, they first need to understand the various throwing strategies in curling competitions and then adjust their motion control parameters to achieve the corresponding strategic throws. However, current curling strategy research lacks mathematical analysis and descriptive methods for throwing strategies tailored to robots. Moreover, research on how robots can solve for corresponding throwing strategies is lacking. These limitations have restricted the application and development of curling robots in the sport. Here, the concepts of the curling stone’s hitting domain and hitting tree are introduced to analyze and describe the curling strategies for robots by constructing the curling hitting domain through a curling collision model and by building the hitting tree through operations such as combination, permutation, and pruning. Furthermore, based on the solution methods for hitting domains and hitting trees, a search solution method for the control parameters of robots is developed. The research findings are integrated into a curling robot auxiliary decision-making software. With the help of the auxiliary software, the curling robot achieves victory in competitions against humans. The research outcomes are of great importance for the application and development of curling robots and legged robots.展开更多
A multiple-legged robot is traditionally controlled by using its dynamic model.But the dynamic-model-based approach fails to acquire satisfactory performances when the robot faces rough terrains and unknown environmen...A multiple-legged robot is traditionally controlled by using its dynamic model.But the dynamic-model-based approach fails to acquire satisfactory performances when the robot faces rough terrains and unknown environments.Referring animals＇ neural control mechanisms,a control model is built for a quadruped robot walking adaptively.The basic rhythmic motion of the robot is controlled by a well-designed rhythmic motion controller（RMC） comprising a central pattern generator（CPG） for hip joints and a rhythmic coupler（RC） for knee joints.CPG and RC have relationships of motion-mapping and rhythmic couple.Multiple sensory-motor models,abstracted from the neural reflexes of a cat,are employed.These reflex models are organized and thus interact with the CPG in three layers,to meet different requirements of complexity and response time to the tasks.On the basis of the RMC and layered biological reflexes,a quadruped robot is constructed,which can clear obstacles and walk uphill and downhill autonomously,and make a turn voluntarily in uncertain environments,interacting with the environment in a way similar to that of an animal.The paper provides a biologically inspired architecture,with which a robot can walk adaptively in uncertain environments in a simple and effective way,and achieve better performances.展开更多
基金Supported by National Natural Science Foundation of China(Grant No.U1613208)
文摘The research on legged robots attracted much attention both from the academia and industry. Legged robots are multi-input multi-output with multiple end-e ector systems. Therefore,the mechanical design and control framework are challenging issues. This paper reviews the development of type synthesis and behavior control on legged robots; introduces the hexapod robots developed in our research group based on the proposed type synthesis method. The control framework for legged robots includes data driven layer,robot behavior layer and robot execution layer. Each layer consists several components which are explained in details. Finally,various experiments were conducted on several hexapod robots. The summarization of the type synthesis and behavior control design constructed in this paper would provide a unified platform for communications and references for future advancement for legged robots.
基金supported by the National Key Research Program of China (2018YFB1304500)the National Natural Science Foundation of China (91748202 and 62073041)
文摘Unmanned systems such as legged robots require fast-motion responses for operation in complex envi-ronments.These systems therefore require explosive actuators that can provide high peak speed or high peak torque at specific moments during dynamic motion.Although hydraulic actuators can provide a large force,they are relatively inefficient,large,and heavy.Industrial electric actuators are incapable of providing instant high power.In addition,the constant reduction ratio of the reducer makes it difficult to eliminate the tradeoff between high speed and high torque in a given system.This study proposes an explosive electric actuator and an associated control method for legged robots.First,a high-power-density variable transmission is designed to enable continuous adjustment of the output speed to torque ratio.A heat-dissipating structure based on a composite phase-change material(PCM)is used.An integral torque control method is used to achieve periodic and controllable explosive power output.Jumping experiments are conducted with typical legged robots to verify the effectiveness of the proposed actuator and control method.Single-legged,quadruped,and humanoid robots jumped to heights of 1.5,0.8,and 0.5 m,respectively.These are the highest values reported to date for legged robots powered by electric actuators.
文摘Adaptive locomotion in different types of surfaces is of critical importance for legged robots.The knowledge of various ground substrates,especially some geological properties,plays an essential role in ensuring the legged robots'safety.In this paper,the interaction between the robots and the environments is investigated through interaction dynamics with the closed-loop system model,the compliant contact model,and the friction model,which unveil the influence of environment's geological characteristics for legged robots'locomotion.The proposed method to classify substrates is based on the interaction dynamics and the sensory-motor coordination.The foot contact forces,joint position errors,and joint motor currents,which reflect body dynamics,are measured as the sensing variables.We train and classify the features extracted from the raw data with a multilevel weighted k-Nearest Neighbor(kNN) algorithm.According to the interaction dynamics,the strategy of adaptive walking is developed by adjusting the touchdown angles and foot trajectories while lifting up and dropping down the foot.Experiments are conducted on five different substrates with quadruped robot FROG-I.The comparison with other classification methods and adaptive walking between different substrates demonstrate the effectiveness of our approach.
文摘The stable slope-walking ability of legged robot walking in any direction on slope is analysed. The contacting angle and leaving angle of leg to the ground are presented. A method to increase the slope-walking ability is proposed only by changing the contacting angle and leaving angle of the leg to the ground.
基金supported in part by the National Natural Science Foundationof China under Grant(61801122)Natural Science Foundation of FujianProvince(2022J01542).
文摘The wheeled bipedal robots have great application potential in environments with a mixture of structured and unstructured terrain. However, wheeled bipedal robots have problems such as poor balance ability and low movement level on rough roads. In this paper, a novel and low-cost wheeled bipedal robot with an asymmetrical five-link mechanism is proposed, and the kinematics of the legs and the dynamics of the Wheeled Inverted Pendulum (WIP) are modeled. The primary balance controller of the wheeled bipedal robot is built based on the Linear Quadratic Regulator (LQR) and the compensation method of the virtual pitch angle adjusting the Center of Mass (CoM) position, then the whole-body hybrid torque-position control is established by combining attitude and leg controllers. The stability of the robot’s attitude control and motion is verified with simulations and prototype experiments, which confirm the robot’s ability to pass through complex terrain and resist external interference. The feasibility and reliability of the proposed control model are verified.
文摘This paper proposes the Leg Dimensional Synergistic Optimization Strategy(LDSOS)for humanoid robotic legs based on mechanism decoupling and performance assignment.The proposed method addresses the interdependent effects of dimensional parameters on the local and whole mechanisms in the design of hybrid humanoid robotic legs.It sequentially optimizes the dimensional parameters of the local and whole mechanism,thereby balancing the motion performance requirements of both.Additionally,it considers the assignment of efficient performance resources between the Local Functional Workspace(LFW)and the Whole Available Workspace(WAW).To facilitate the modeling and optimization process,a local/whole Equivalent Configuration Framework(ECF)is introduced.By decoupling the hybrid mechanism into a whole mechanism and multiple local mechanisms,the ECF enhances the efficiency of design,modeling,and performance evaluation.Prototype experiments are conducted to validate the effectiveness of LDSOS.This research provides an effective configuration framework for humanoid robotic leg design,establishing a theoretical and practical foundation for future optimized designs of humanoid robotic legs and pioneering novel approaches to the design of complex hybrid humanoid robotic legs.
基金supported by the National Basic Research Program of China("973" Program)(Grant No.2013CB035502)the International Sci-ence and Technology Cooperation Project with Russia(Grant No.2010DFR70270)+2 种基金the National Natural Science Foundation of China(Grant No.51275106)the"111" Project(Grant No.B07018)the Key Laboratory Opening Funding of Aerospace Mechanism and Control(Grant No.HIT.KLOF.2010057)
文摘Heavy-duty legged robots have been regarded as one of the important developments in the field of legged robots because of their high payload-total mass ratio,terrain adaptability,and multitasking.The problems associated with the development and use of heavy-duty legged robots have motivated researchers to conduct many important studies,covering topics related to the mechanical structure,force distribution,control strategy,energy efficiency,etc.Overall,heavy-duty legged robots have three main characteristics:greater body masses,larger body sizes,and higher payload-total mass ratios.Thus,various heavy-duty legged robots and their performances are reviewed here.This review presents the current developments with regard to heavy-duty legged robots.Also,the main characteristics of high-performance heavy-duty legged robots are determined and conclusions are drawn.Furthermore,the current research of key techniques of heavy-duty legged robots,including the mechanical structure,force distribution,control method,and power source,is described.To assess the transportation capacity of heavy-duty legged robots,performance evaluation parameters are proposed.Finally,problems that need further research are addressed.
基金Supported by National Basic Research Program of China(973 Program,Grant No.2013CB035501)
文摘Human tracking is an important issue for intelligent robotic control and can be used in many scenarios, such as robotic services and human-robot cooperation. Most of current human-tracking methods are targeted for mobile/tracked robots, but few of them can be used for legged robots. Two novel human-tracking strategies, view priority strategy and distance priority strategy, are proposed specially for legged robots, which enable them to track humans in various complex terrains. View priority strategy focuses on keeping humans in its view angle arrange with priority, while its counterpart, distance priority strategy, focuses on keeping human at a reasonable distance with priority. To evaluate these strategies, two indexes（average and minimum tracking capability） are defined. With the help of these indexes, the view priority strategy shows advantages compared with distance priority strategy. The optimization is done in terms of these indexes, which let the robot has maximum tracking capability. The simulation results show that the robot can track humans with different curves like square, circular, sine and screw paths. Two novel control strategies are proposed which specially concerning legged robot characteristics to solve human tracking problems more efficiently in rescue circumstances.
基金supported by the National Key R&D Program of China(Grant No.2021YFF0306202).
文摘This paper proposes a novel continuous footholds optimization method for legged robots to expand their walking ability on complex terrains.The algorithm can efficiently run onboard and online by using terrain perception information to protect the robot against slipping or tripping on the edge of obstacles,and to improve its stability and safety when walking on complex terrain.By relying on the depth camera installed on the robot and obtaining the terrain heightmap,the algorithm converts the discrete grid heightmap into a continuous costmap.Then,it constructs an optimization function combined with the robot’s state information to select the next footholds and generate the motion trajectory to control the robot’s locomotion.Compared with most existing footholds selection algorithms that rely on discrete enumeration search,as far as we know,the proposed algorithm is the first to use a continuous optimization method.We successfully implemented the algorithm on a hexapod robot,and verified its feasibility in a walking experiment on a complex terrain.
基金supported by the National Natural Science Foundation of China(62003190)the Shandong Provincial Natural Science Foundation(ZR201911040226)the Open Research Projects of Zhejiang Lab(2022NB0AB06).
文摘Terrain classification information is of great significance for legged robots to traverse various terrains.Therefore,this communication presents an online terrain classification framework for legged robots,utilizing the acoustic signals produced during locomotion.The Mel-Frequency Cepstral Coefficient(MFCC)feature vectors are extracted from the acoustic data recorded by an on-board microphone.Then the Gaussian mixture models(GMMs)are used to classify the MFCC features into different terrain type categories.The proposed framework was validated on a quadruped robot.Overall,our investigations achieved a classification time-resolution of 1 s when the robot trotted over three kinds of terrains,thus recording a comprehensive success rate of 92.7%.
基金Supported by National Key Research and Development Program of China(Grant No.2021YFF0306202).
文摘The current gait planning for legged robots is mostly based on human presets,which cannot match the flexible characteristics of natural mammals.This paper proposes a gait optimization framework for hexapod robots called Smart Gait.Smart Gait contains three modules:swing leg trajectory optimization,gait period&duty optimization,and gait sequence optimization.The full dynamics of a single leg,and the centroid dynamics of the overall robot are considered in the respective modules.The Smart Gait not only helps the robot to decrease the energy consumption when in locomotion,mostly,it enables the hexapod robot to determine its gait pattern transitions based on its current state,instead of repeating the formalistic clock-set step cycles.Our Smart Gait framework allows the hexapod robot to behave nimbly as a living animal when in 3D movements for the first time.The Smart Gait framework combines offline and online optimizations without any fussy data-driven training procedures,and it can run efficiently on board in real-time after deployment.Various experiments are carried out on the hexapod robot LittleStrong.The results show that the energy consumption is reduced by 15.9%when in locomotion.Adaptive gait patterns can be generated spontaneously both in regular and challenge environments,and when facing external interferences.
基金Zhejiang Province Key Research and Development Project of China,Grant/Award Number:2021C01069。
文摘The bionic joints composed of pneumatic muscles(PMs)can simulate the motion of biological joints.However,the PMs themselves have non-linear characteristics such as hysteresis and creep,which make it difficult to achieve high-precision trajectory tracking control of PM-driven robots.In order to effectively suppress the adverse effects of non-linearity on control performance and improve the dynamic performance of PM-driven legged robot,this study designs a double closed-loop control structure based on neural network.First,according to the motion model of the bionic joint,a mapping model between PM contraction force and joint torque is proposed.Second,a control strategy is designed for the inner loop of PM contraction force and the outer loop of bionic joint angle.In the inner control loop,a feedforward neuron Proportional-Integral-Derivative controller is designed based on the PM three-element model.In the control outer loop,a sliding mode robust controller with local model approximation is designed by using the radial basis function neural network approximation capability.Finally,it is verified by simulation and physical experiments that the designed control strategy is suitable for humanoid motion control of antagonistic PM joints,and it can satisfy the requirements of reliability,flexibility,and bionics during human–robot collaboration.
基金National Natural Science Foundation of China(Grant No.51735009)。
文摘This paper presents an effective way to support motion planning of legged mobile robots—Inverted Modelling,based on the equivalent metamorphic mechanism concept.The difference from the previous research is that we herein invert the equivalent parallel mechanism.Assuming the leg mechanisms are hybrid links,the body of robot being considered as fixed platform,and ground as moving platform.The motion performance is transformed and measured in the body frame.Terrain and joint limits are used as input parameters to the model,resulting in the representation which is independent of terrains and particular poses in Inverted Modelling.Hence,it can universally be applied to any kind of legged robots as global motion performance framework.Several performance measurements using Inverted Modelling are presented and used in motion performance evaluation.According to the requirements of actual work like motion continuity and stability,motion planning of legged robot can be achieved using different measurements on different terrains.Two cases studies present the simulations of quadruped and hexapod robots walking on rugged roads.The results verify the correctness and effectiveness of the proposed method.
基金supported by the National Natural Science Foundation of China(Grant No.92248303).
文摘In curling competitions, the throwing strategy has a decisive influence on the outcome of the game. When robots are applied to the sport of curling, they first need to understand the various throwing strategies in curling competitions and then adjust their motion control parameters to achieve the corresponding strategic throws. However, current curling strategy research lacks mathematical analysis and descriptive methods for throwing strategies tailored to robots. Moreover, research on how robots can solve for corresponding throwing strategies is lacking. These limitations have restricted the application and development of curling robots in the sport. Here, the concepts of the curling stone’s hitting domain and hitting tree are introduced to analyze and describe the curling strategies for robots by constructing the curling hitting domain through a curling collision model and by building the hitting tree through operations such as combination, permutation, and pruning. Furthermore, based on the solution methods for hitting domains and hitting trees, a search solution method for the control parameters of robots is developed. The research findings are integrated into a curling robot auxiliary decision-making software. With the help of the auxiliary software, the curling robot achieves victory in competitions against humans. The research outcomes are of great importance for the application and development of curling robots and legged robots.
基金supported by National Natural Science Foundation of China (Grant No. 50905012)the Fundamental Research Funds for the Central Universities of China (Grant No. 2012JBM088)
文摘A multiple-legged robot is traditionally controlled by using its dynamic model.But the dynamic-model-based approach fails to acquire satisfactory performances when the robot faces rough terrains and unknown environments.Referring animals＇ neural control mechanisms,a control model is built for a quadruped robot walking adaptively.The basic rhythmic motion of the robot is controlled by a well-designed rhythmic motion controller（RMC） comprising a central pattern generator（CPG） for hip joints and a rhythmic coupler（RC） for knee joints.CPG and RC have relationships of motion-mapping and rhythmic couple.Multiple sensory-motor models,abstracted from the neural reflexes of a cat,are employed.These reflex models are organized and thus interact with the CPG in three layers,to meet different requirements of complexity and response time to the tasks.On the basis of the RMC and layered biological reflexes,a quadruped robot is constructed,which can clear obstacles and walk uphill and downhill autonomously,and make a turn voluntarily in uncertain environments,interacting with the environment in a way similar to that of an animal.The paper provides a biologically inspired architecture,with which a robot can walk adaptively in uncertain environments in a simple and effective way,and achieve better performances.
