This work presents a trajectory tracking control method for snake robots.This method eliminates the influence of time-varying interferences on the body and reduces the offset error of a robot with a predetermined traj...This work presents a trajectory tracking control method for snake robots.This method eliminates the influence of time-varying interferences on the body and reduces the offset error of a robot with a predetermined trajectory.The optimized line-of-sight(LOS)guidance strategy drives the robot’s steering angle to maintain its anti-sideslip ability by predicting position errors and interferences.Then,the predictions of system parameters and viscous friction coefficients can compensate for the joint torque control input.The compensation is adopted to enhance the compatibility of a robot within ever-changing environments.Simulation and experimental outcomes show that our work can decrease the fluctuation peak of the tracking errors,reduce adjustment time,and improve accuracy.展开更多
This paper presents a finite-time sideslip differentiator-based line-of-sight(LOS)guidance method for robust path following of snake robots.Firstly,finite-time stable sideslip differentiator and adaptive LOS guidance ...This paper presents a finite-time sideslip differentiator-based line-of-sight(LOS)guidance method for robust path following of snake robots.Firstly,finite-time stable sideslip differentiator and adaptive LOS guidance method are proposed to counteract sideslip drift caused by cross-track velocity.The proposed differentiator can accurately observe the cross-track error and sideslip angle for snake robots to avoid errors caused by calculating sideslip angle approximately.In our method,the designed piecewise auxiliary function guarantees the finite-time stability of position errors.Secondly,for the case of external disturbances and state constraints,a Barrier Lyapunov functionbased backstepping adaptive path following controller is presented to improve the robot’s robustness.The uniform ultimate boundedness of the closed-loop system is proved by analyzing stability.Additionally,a gait frequency adjustment-based virtual velocity control input is derived to achieve the exponential convergence of the tangential velocity.At last,the availability and superiority of this work are shown through simulation and experiment results.展开更多
Snake Robots(SR)have been successfully deployed and proved to attain bio-inspired solutions owing to its capability to move in harsh environments,a characteristic not found in other kinds of robots(like wheeled or leg...Snake Robots(SR)have been successfully deployed and proved to attain bio-inspired solutions owing to its capability to move in harsh environments,a characteristic not found in other kinds of robots(like wheeled or legged robots).Underwater Snake Robots(USR)establish a bioinspired solution in the domain of underwater robotics.It is a key challenge to increase the motion efficiency in underwater robots,with respect to forwarding speed,by enhancing the locomotion method.At the same time,energy efficiency is also considered as a crucial issue for long-term automation of the systems.In this aspect,the current research paper concentrates on the design of effectual Locomotion of Bioinspired Underwater Snake Robots using Metaheuristic Algorithm(LBIUSR-MA).The proposed LBIUSR-MA technique derives a bi-objective optimization problem to maximize the ForwardVelocity(FV)and minimize the Average Power Consumption(APC).LBIUSR-MA technique involves the design ofManta Ray Foraging Optimization(MRFO)technique and derives two objective functions to resolve the optimization issue.In addition to these,effective weighted sum technique is also used for the integration of two objective functions.Moreover,the objective functions are required to be assessed for varying gait variables so as to inspect the performance of locomotion.A detailed set of simulation analyses was conducted and the experimental results demonstrate that the developed LBIUSR-MA method achieved a low Average Power Consumption(APC)value of 80.52W underδvalue of 50.The proposed model accomplished the minimum PAC and maximum FV of USR in an effective manner.展开更多
Thanks to the special physical architectures and various locomotion gaits,snake robots may offer significant benefits over traditional legged or wheeled locomotion designs in vast types of scenarios.This paper propose...Thanks to the special physical architectures and various locomotion gaits,snake robots may offer significant benefits over traditional legged or wheeled locomotion designs in vast types of scenarios.This paper proposes an innovative snake robot with digitally-actuated Stewart platforms as its modules and mainly focuses on the simulations of various snake gaits.Three categories of fitting algorithms are elaborated in simulations of lateral undulation and Configuration-Fitting Algorithm of Four Modules is demonstrated as a universal gait fitting algorithm for all kinds of snake robots with binary actuators.Several typical snake gaits are simulated and the results demonstrate the excellent mobility of the snake robot.展开更多
The versatile motion capability of snake robots offers themselves robust adaptability in varieties of challenging environments where traditional robots may be incapacitated.This study reports a novel flexible snake ro...The versatile motion capability of snake robots offers themselves robust adaptability in varieties of challenging environments where traditional robots may be incapacitated.This study reports a novel flexible snake robot featuring a rigid-flexible coupling structure and multiple motion gaits.To better understand the robot's behavior,a bending model for the soft actuator is established.Furthermore,a dynamic model is developed to map the relationship between the input air pressure and joint torque,which is the model base for controlling the robot effectively.Based on the wave motion generated by the joint coupling direction function in different planes,multiple motion gait planning methods of the snake-like robot are proposed.In order to evaluate the adaptability and maneuverability of the developed snake robot,extensive experiments were conducted in complex environments.The results demonstrate the robot's effectiveness in navigating through intricate settings,underscoring its potential for applications in various fields.展开更多
The vast diversity of morphologies,body size,and lifestyles of snakes represents an important source of information that can be used to derive bio-inspired robots through a biology-push and pull process.An understandi...The vast diversity of morphologies,body size,and lifestyles of snakes represents an important source of information that can be used to derive bio-inspired robots through a biology-push and pull process.An understanding of the detailed kinematics of swimming snakes is a fundamental prerequisite to conceive and design bio-inspired aquatic snake robots.However,only limited information is available on the kinematics of swimming snake.Fast and accurate methods are needed to fill this knowledge gap.In the present paper,three existing methods were compared to test their capacity to characterize the kinematics of swimming snakes.(1)Marker tracking(Deftac),(2)Markerless pose estimation(DeepLabCut),and(3)Motion capture were considered.(4)We also designed and tested an automatic video processing method.All methods provided different albeit complementary data sets;they also involved different technical issues in terms of experimental conditions,snake manipulation,or processing resources.Marker tracking provided accurate data that can be used to calibrate other methods.Motion capture posed technical difficulties but can provide limited 3D data.Markerless pose estimation required deep learning(thus time)but was efficient to extract the data under various experimental conditions.Finally,automatic video processing was particularly efficient to extract a wide range of data useful for both biology and robotics but required a specific experimental setting.展开更多
In the field of pipeline inner wall inspection,the snake robot demonstrates significant advantages over other inspection methods.While a simple traveling wave or meandering motion will suffice for inspecting the inner...In the field of pipeline inner wall inspection,the snake robot demonstrates significant advantages over other inspection methods.While a simple traveling wave or meandering motion will suffice for inspecting the inner wall of small-diameter pipes,comprehensively and meticulously inspecting the inner wall of large-diameter pipes requires the snake robot to adopt a helical gait that closely adheres to the inner wall.Our review of existing literature indicates that most research and development on the helical gait of snake robots has focused on the outer surface of cylinders,with very few studies dedicated to developing a helical gait specifically for the inspection of the inner wall of pipes.Therefore,in this study,we propose a helical gait that is suitable for the inner wall of pipes and meets the requirements of gas pipeline engineering.The helical gait is designed using the backbone curve method.First,we create a mathematical model for a circular helix curve with constant curvature and torsion,ensuring it is applicable to a snake robot prototype in a laboratory environment.Subsequently.we calculate the joint angles required for two conical spiral curves with variable curvature and torsion,establish a new model,and define the physical significance of the specific parameters.To ensure the feasibility of the proposed gait,we conduct experiments involving meandering and traveling wave motions to verify the communication and control between the host computer and the snake robot.Building upon this foundation,we further validate the mathematical model of the complex helical motion gait through simulation experiments.Our findings provide a theoretical basis for realizing helical movement with a real snake robot.展开更多
Snake robots have great potential for exploring and operating in challenging unstructured environments,such as rubble,caves,and narrow pipelines.However,due to the complexity and unpredictability of unstructured envir...Snake robots have great potential for exploring and operating in challenging unstructured environments,such as rubble,caves,and narrow pipelines.However,due to the complexity and unpredictability of unstructured environments,designing a controller that can achieve adaptive motion is crucial.This paper proposes a self-adaptive torque-based rolling controller for snake robots,enabling compliant motion in unstructured environments.First,a controller is designed to modify the torque of each motor by focusing on the different motion states of the rolling gait.Second,an experimental platform is established for snake robots to verify the effectiveness of the controller.Finally,a series of rolling experiments are conducted using the torque-based rolling controller.In conclusion,the self-adaptive torque-based rolling controller enhances snake robot adaptability and mobility.展开更多
While cable-driven snake robots are promising in exploring confined spaces, their hyper-redundancy makes the collision-free motion planning difficult. In this paper, by combining the prediction lookup and interpolatio...While cable-driven snake robots are promising in exploring confined spaces, their hyper-redundancy makes the collision-free motion planning difficult. In this paper, by combining the prediction lookup and interpolation algorithms, we present a new path following method for cable-driven snake robots to high-efficiently slither into complex terrains along a desired path. In our method, we first discretize the desired path into points, and develop the prediction lookup algorithm to efficiently find the points matched with joints of the robot. According to geometric relations between the prediction lookup results and link length of the robot, we develop the interpolation algorithm to reduce the tracking errors caused by the discretization. Finally, simulations and experiments of inspections in two confined spaces including the obstacle array and pipe tank system are performed on our custom-built 25 degree of freedoms(DOFs) cable-driven snake robot. The results demonstrate that the presented method can successfully navigate our snake robot into confined spaces with high computational efficiency and good accuracy, which well verifies effectiveness of our development.展开更多
In this paper, a dynamic model for an underwater snake-like robot is developed based on Kane's dynamic equations. This methodology allows construction of the dynamic model simply and incrementally. The partial vel...In this paper, a dynamic model for an underwater snake-like robot is developed based on Kane's dynamic equations. This methodology allows construction of the dynamic model simply and incrementally. The partial velocity is deduced. The forces which contribute to dynamics are determined by Kane's approach. The generalized active forces and the generalized inertia forces are deduced. The model developed in this paper includes inertia force, inertia moment, gravity, control torques, and three major hydrodynamic forces: added mass, profile drag and buoyancy. The equations of hydrodynamic forces are deduced. Kane's method provides a direct approach for incorporating external environmental forces into the model. The dynamic model developed in this paper is obtained in a closed form which is well suited for control purposes. It is also computationally efficient and has physical insight into what forces really influence the system dynamics. The simulation result shows that the proposed method is feasible.展开更多
A systematic method for swimming control of the underwater snake-like robot is still lacking. We construct a simulation platform of the underwater snake-like robot swimming based on Kane's dynamic model and centra...A systematic method for swimming control of the underwater snake-like robot is still lacking. We construct a simulation platform of the underwater snake-like robot swimming based on Kane's dynamic model and central pattern generator(CPG). The partial velocity is deduced. The forces which contribute to dynamics are determined by Kane's approach. Hydrodynamic coefficients are determined by experiments. Then, we design a CPG-based control architecture implemented as the system of coupled nonlinear oscillators. The CPG, like its biological counterpart, can produce coordinated patterns of rhythmic activity while being modulated by simple control parameters. The relations between the CPG parameters and the speed of the underwater snake-like robot swimming are investigated. Swimming in a straight line, turning, and switching between swimming modes are implemented in our simulation platform to prove the feasibility of the proposed simulation platform. The results show that the simulation platform can imitate different swimming modes of the underwater snake-like robot.展开更多
We propose a biomimetic approach for steering motion control of a snake robot. Inspired by a vertebrate biological motor system paradigm, a hierarchical control scheme is adopted. In the control scheme, an artificial ...We propose a biomimetic approach for steering motion control of a snake robot. Inspired by a vertebrate biological motor system paradigm, a hierarchical control scheme is adopted. In the control scheme, an artificial central pattern generator(CPG) is employed to generate serpentine locomotion in the robot. This generator outputs the coordinated desired joint angle commands to each lower-level effector controller, while the locomotion can be controlled through CPG modulation by a higher-level motion controller. The motion controller consists of a cerebellar model articulation controller(CMAC) and a proportional-derivative(PD) controller. Because of the fast learning ability of the CMAC, the proposed motion controller can drive the robot to track the desired orientation and adapt to unexpected perturbations. The PD controller is employed to expedite the convergence speed of the motion controller. Finally, both numerical studies and experiments proved that the proposed approach can help the snake robot achieve good tracking performance and adaptability in a varying environment.展开更多
In order to solve oscillation of head of the underwater snake-like robot,the Central Pattern Generator( CPG)-based control scheme with head-controller was presented. The Kane dynamic model was constructed to be proces...In order to solve oscillation of head of the underwater snake-like robot,the Central Pattern Generator( CPG)-based control scheme with head-controller was presented. The Kane dynamic model was constructed to be processed with a commercial package MotionGenesis Kane 5. 3,to which the proposed control scheme was applied. The relation between CPG parameters and orientation offset of head was investigated. The target orientation of head-controller was calculated through a convenient method. The advantage of this control scheme is that the head of the underwater snake-like robot remains in the forward direction during swimming. To prove the feasibility of the proposed methodology,two basic motion patterns,swimming along the straight line and swimming along the curved path,had been implemented in our simulation platform. The results showed that the simulation platform can imitate the swimming of the underwater snake-like robot and the head of the underwater snake-like robot remains in a fixed orientation directed towards the target. The oscillation of head's orientation is inhibited effectively.展开更多
Marvi et al(Science,2014,vol.346,p.224)concluded a sidewinder rattlesnake increases the body contact length with the sand when granular incline angle increases.They also claimed the same principle should work on robot...Marvi et al(Science,2014,vol.346,p.224)concluded a sidewinder rattlesnake increases the body contact length with the sand when granular incline angle increases.They also claimed the same principle should work on robotic snake too.We have evidence to prove that this conclusion is only partial in describing the snake body-sand interaction.There should be three phases that fully represent the snake locomotion behaviors during ascent of sandy slopes,namely lifting,descending,and ceasing.The snake body-sand interaction during the descending and ceasing phases helps with the climbing while such interaction during the lifting phase in fact contributes resistance.展开更多
A MNSM( mirror neuron system mechanism)-based controller is developed to present the swimming rhythm of a snake-like robot in Cartesian space. From engineering viewpoint,the proposed controller is composed of a neuron...A MNSM( mirror neuron system mechanism)-based controller is developed to present the swimming rhythm of a snake-like robot in Cartesian space. From engineering viewpoint,the proposed controller is composed of a neuron for rhythm angle and two neurons for motion knowledge in XY plane. The given knowledge is a rhythm curve for swimming motion of a snake-like robot. Experimental results show that the proposed controller can present the knowledge of swimming rhythm,which represents the corresponding control law to drive the snake-like robot to swim with different speeds and turning motion. This work provides a novel method to present the knowledge for swimming motion of snake-like robots.展开更多
In prior research,the orientation of head of the snake-like robot is changed according to the sinusoidal wave. To solve this problem,we propose Central Pattern Generator( CPG)-based control scheme with head-controller...In prior research,the orientation of head of the snake-like robot is changed according to the sinusoidal wave. To solve this problem,we propose Central Pattern Generator( CPG)-based control scheme with head-controller to stabilize the head of the underwater snake-like robot. The advantage of the CPG-based control scheme with head-controller is that the head of the underwater snake-like robot is direct to the target orientation during swimming. The relation between CPG parameters and orientation stability of head is discussed.The adaptation of the proposed method to environment changes is tested. The influences of CPG parameters and hydrodynamic forces on the orientation offset of head are investigated. The target orientation( the input of headcontroller) with an experimental optimization is calculated through a convenient method. To prove the feasibility of the proposed methodology,the different swimming modes have been implemented in our simulation platform.The results show that the oscillation of head's orientation is inhibited effectively,and the proposed method has strong adaptation to environment and CPG parameters changes.展开更多
From a bionics viewpoint , this paper proposes a mechanical model of a wheeled snake like mobile mechanism. On the hypothesis of the existing non holonomic constraints on the robot kinematics, we set up the relation...From a bionics viewpoint , this paper proposes a mechanical model of a wheeled snake like mobile mechanism. On the hypothesis of the existing non holonomic constraints on the robot kinematics, we set up the relationship among the kinetic control parameters in the snake like movement using Lie group and Lie algebra of the principle fiber bundle and provide some theoretical control methods to realize the snake like locomotion.展开更多
基金supported in part by the National Natural Science Foundation of China(U2241228,62273019,61825305,U1933125,72192820,72192824,62171274)the China Postdoctoral Science Foundation(2022M710093)the Open Project Program of the Key Laboratory for Agricultural Machinery Intelligent Control and Manufacturing of Fujian Education Institutions(AMICM202102)。
文摘This work presents a trajectory tracking control method for snake robots.This method eliminates the influence of time-varying interferences on the body and reduces the offset error of a robot with a predetermined trajectory.The optimized line-of-sight(LOS)guidance strategy drives the robot’s steering angle to maintain its anti-sideslip ability by predicting position errors and interferences.Then,the predictions of system parameters and viscous friction coefficients can compensate for the joint torque control input.The compensation is adopted to enhance the compatibility of a robot within ever-changing environments.Simulation and experimental outcomes show that our work can decrease the fluctuation peak of the tracking errors,reduce adjustment time,and improve accuracy.
基金supported in part by the National Natural Science Foundation of China(61825305,62171274,U1933125,U2241228,62273019)the Shanghai Science and Technology Major Project(2021SHZDZX)+2 种基金the National Natural Science Foundation of China through the Main Research Projecton Machine Behavior and Human-Machine Collaborated Decision Making Methodology(72192820)the Third Research Projecton Human Behavior in HumanMachine Collaboration(72192822)the China Postdoctoral Science Foundation(2022M710093)。
文摘This paper presents a finite-time sideslip differentiator-based line-of-sight(LOS)guidance method for robust path following of snake robots.Firstly,finite-time stable sideslip differentiator and adaptive LOS guidance method are proposed to counteract sideslip drift caused by cross-track velocity.The proposed differentiator can accurately observe the cross-track error and sideslip angle for snake robots to avoid errors caused by calculating sideslip angle approximately.In our method,the designed piecewise auxiliary function guarantees the finite-time stability of position errors.Secondly,for the case of external disturbances and state constraints,a Barrier Lyapunov functionbased backstepping adaptive path following controller is presented to improve the robot’s robustness.The uniform ultimate boundedness of the closed-loop system is proved by analyzing stability.Additionally,a gait frequency adjustment-based virtual velocity control input is derived to achieve the exponential convergence of the tangential velocity.At last,the availability and superiority of this work are shown through simulation and experiment results.
文摘Snake Robots(SR)have been successfully deployed and proved to attain bio-inspired solutions owing to its capability to move in harsh environments,a characteristic not found in other kinds of robots(like wheeled or legged robots).Underwater Snake Robots(USR)establish a bioinspired solution in the domain of underwater robotics.It is a key challenge to increase the motion efficiency in underwater robots,with respect to forwarding speed,by enhancing the locomotion method.At the same time,energy efficiency is also considered as a crucial issue for long-term automation of the systems.In this aspect,the current research paper concentrates on the design of effectual Locomotion of Bioinspired Underwater Snake Robots using Metaheuristic Algorithm(LBIUSR-MA).The proposed LBIUSR-MA technique derives a bi-objective optimization problem to maximize the ForwardVelocity(FV)and minimize the Average Power Consumption(APC).LBIUSR-MA technique involves the design ofManta Ray Foraging Optimization(MRFO)technique and derives two objective functions to resolve the optimization issue.In addition to these,effective weighted sum technique is also used for the integration of two objective functions.Moreover,the objective functions are required to be assessed for varying gait variables so as to inspect the performance of locomotion.A detailed set of simulation analyses was conducted and the experimental results demonstrate that the developed LBIUSR-MA method achieved a low Average Power Consumption(APC)value of 80.52W underδvalue of 50.The proposed model accomplished the minimum PAC and maximum FV of USR in an effective manner.
基金supported by the Research Fund of State Key Laboratory of Mechanical System and Vibration,China(Grant No.MSV-2010-07)
文摘Thanks to the special physical architectures and various locomotion gaits,snake robots may offer significant benefits over traditional legged or wheeled locomotion designs in vast types of scenarios.This paper proposes an innovative snake robot with digitally-actuated Stewart platforms as its modules and mainly focuses on the simulations of various snake gaits.Three categories of fitting algorithms are elaborated in simulations of lateral undulation and Configuration-Fitting Algorithm of Four Modules is demonstrated as a universal gait fitting algorithm for all kinds of snake robots with binary actuators.Several typical snake gaits are simulated and the results demonstrate the excellent mobility of the snake robot.
基金financially supported by the Joint Fund of National Natural Science Foundation of China with Shenzhen City(U2013212)the National Key R&D Program of China(2020YFB1313001).
文摘The versatile motion capability of snake robots offers themselves robust adaptability in varieties of challenging environments where traditional robots may be incapacitated.This study reports a novel flexible snake robot featuring a rigid-flexible coupling structure and multiple motion gaits.To better understand the robot's behavior,a bending model for the soft actuator is established.Furthermore,a dynamic model is developed to map the relationship between the input air pressure and joint torque,which is the model base for controlling the robot effectively.Based on the wave motion generated by the joint coupling direction function in different planes,multiple motion gait planning methods of the snake-like robot are proposed.In order to evaluate the adaptability and maneuverability of the developed snake robot,extensive experiments were conducted in complex environments.The results demonstrate the robot's effectiveness in navigating through intricate settings,underscoring its potential for applications in various fields.
基金Agence Nationale de la recherche(Grant no.ANR-20-CE02-0010).
文摘The vast diversity of morphologies,body size,and lifestyles of snakes represents an important source of information that can be used to derive bio-inspired robots through a biology-push and pull process.An understanding of the detailed kinematics of swimming snakes is a fundamental prerequisite to conceive and design bio-inspired aquatic snake robots.However,only limited information is available on the kinematics of swimming snake.Fast and accurate methods are needed to fill this knowledge gap.In the present paper,three existing methods were compared to test their capacity to characterize the kinematics of swimming snakes.(1)Marker tracking(Deftac),(2)Markerless pose estimation(DeepLabCut),and(3)Motion capture were considered.(4)We also designed and tested an automatic video processing method.All methods provided different albeit complementary data sets;they also involved different technical issues in terms of experimental conditions,snake manipulation,or processing resources.Marker tracking provided accurate data that can be used to calibrate other methods.Motion capture posed technical difficulties but can provide limited 3D data.Markerless pose estimation required deep learning(thus time)but was efficient to extract the data under various experimental conditions.Finally,automatic video processing was particularly efficient to extract a wide range of data useful for both biology and robotics but required a specific experimental setting.
基金supported by the BUCEA Post Graduate Innovation Project,China(PG2023096).
文摘In the field of pipeline inner wall inspection,the snake robot demonstrates significant advantages over other inspection methods.While a simple traveling wave or meandering motion will suffice for inspecting the inner wall of small-diameter pipes,comprehensively and meticulously inspecting the inner wall of large-diameter pipes requires the snake robot to adopt a helical gait that closely adheres to the inner wall.Our review of existing literature indicates that most research and development on the helical gait of snake robots has focused on the outer surface of cylinders,with very few studies dedicated to developing a helical gait specifically for the inspection of the inner wall of pipes.Therefore,in this study,we propose a helical gait that is suitable for the inner wall of pipes and meets the requirements of gas pipeline engineering.The helical gait is designed using the backbone curve method.First,we create a mathematical model for a circular helix curve with constant curvature and torsion,ensuring it is applicable to a snake robot prototype in a laboratory environment.Subsequently.we calculate the joint angles required for two conical spiral curves with variable curvature and torsion,establish a new model,and define the physical significance of the specific parameters.To ensure the feasibility of the proposed gait,we conduct experiments involving meandering and traveling wave motions to verify the communication and control between the host computer and the snake robot.Building upon this foundation,we further validate the mathematical model of the complex helical motion gait through simulation experiments.Our findings provide a theoretical basis for realizing helical movement with a real snake robot.
基金supported by the National Natural Science Foundation of China(62072335)Fundamental Research Funds for the Central Universities,China(buctrc202215).
文摘Snake robots have great potential for exploring and operating in challenging unstructured environments,such as rubble,caves,and narrow pipelines.However,due to the complexity and unpredictability of unstructured environments,designing a controller that can achieve adaptive motion is crucial.This paper proposes a self-adaptive torque-based rolling controller for snake robots,enabling compliant motion in unstructured environments.First,a controller is designed to modify the torque of each motor by focusing on the different motion states of the rolling gait.Second,an experimental platform is established for snake robots to verify the effectiveness of the controller.Finally,a series of rolling experiments are conducted using the torque-based rolling controller.In conclusion,the self-adaptive torque-based rolling controller enhances snake robot adaptability and mobility.
基金supported by the National Natural Science Foundation of China(Grant Nos.51435010,and 91848204)。
文摘While cable-driven snake robots are promising in exploring confined spaces, their hyper-redundancy makes the collision-free motion planning difficult. In this paper, by combining the prediction lookup and interpolation algorithms, we present a new path following method for cable-driven snake robots to high-efficiently slither into complex terrains along a desired path. In our method, we first discretize the desired path into points, and develop the prediction lookup algorithm to efficiently find the points matched with joints of the robot. According to geometric relations between the prediction lookup results and link length of the robot, we develop the interpolation algorithm to reduce the tracking errors caused by the discretization. Finally, simulations and experiments of inspections in two confined spaces including the obstacle array and pipe tank system are performed on our custom-built 25 degree of freedoms(DOFs) cable-driven snake robot. The results demonstrate that the presented method can successfully navigate our snake robot into confined spaces with high computational efficiency and good accuracy, which well verifies effectiveness of our development.
基金the National Natural Science Foundation of China(No.51009091)the Special ResearchFund for the Doctoral Program of Higher Education ofChina(No.20100073120016)
文摘In this paper, a dynamic model for an underwater snake-like robot is developed based on Kane's dynamic equations. This methodology allows construction of the dynamic model simply and incrementally. The partial velocity is deduced. The forces which contribute to dynamics are determined by Kane's approach. The generalized active forces and the generalized inertia forces are deduced. The model developed in this paper includes inertia force, inertia moment, gravity, control torques, and three major hydrodynamic forces: added mass, profile drag and buoyancy. The equations of hydrodynamic forces are deduced. Kane's method provides a direct approach for incorporating external environmental forces into the model. The dynamic model developed in this paper is obtained in a closed form which is well suited for control purposes. It is also computationally efficient and has physical insight into what forces really influence the system dynamics. The simulation result shows that the proposed method is feasible.
基金the National Natural Science Foundation of China(No.51009091)the Special Research Fund for the Doctoral Program of Higher Education of China(No.20100073120016)
文摘A systematic method for swimming control of the underwater snake-like robot is still lacking. We construct a simulation platform of the underwater snake-like robot swimming based on Kane's dynamic model and central pattern generator(CPG). The partial velocity is deduced. The forces which contribute to dynamics are determined by Kane's approach. Hydrodynamic coefficients are determined by experiments. Then, we design a CPG-based control architecture implemented as the system of coupled nonlinear oscillators. The CPG, like its biological counterpart, can produce coordinated patterns of rhythmic activity while being modulated by simple control parameters. The relations between the CPG parameters and the speed of the underwater snake-like robot swimming are investigated. Swimming in a straight line, turning, and switching between swimming modes are implemented in our simulation platform to prove the feasibility of the proposed simulation platform. The results show that the simulation platform can imitate different swimming modes of the underwater snake-like robot.
基金Project supported by the Zhejiang Provincial Natural Science Foundation of China(No.LQ16F030002)
文摘We propose a biomimetic approach for steering motion control of a snake robot. Inspired by a vertebrate biological motor system paradigm, a hierarchical control scheme is adopted. In the control scheme, an artificial central pattern generator(CPG) is employed to generate serpentine locomotion in the robot. This generator outputs the coordinated desired joint angle commands to each lower-level effector controller, while the locomotion can be controlled through CPG modulation by a higher-level motion controller. The motion controller consists of a cerebellar model articulation controller(CMAC) and a proportional-derivative(PD) controller. Because of the fast learning ability of the CMAC, the proposed motion controller can drive the robot to track the desired orientation and adapt to unexpected perturbations. The PD controller is employed to expedite the convergence speed of the motion controller. Finally, both numerical studies and experiments proved that the proposed approach can help the snake robot achieve good tracking performance and adaptability in a varying environment.
基金Sponsored by the National Nature Science Foundation of China(Grant No.51009091)the Special Research Fund for the Doctoral Program of Higher Education(Grant No.20100073120016)
文摘In order to solve oscillation of head of the underwater snake-like robot,the Central Pattern Generator( CPG)-based control scheme with head-controller was presented. The Kane dynamic model was constructed to be processed with a commercial package MotionGenesis Kane 5. 3,to which the proposed control scheme was applied. The relation between CPG parameters and orientation offset of head was investigated. The target orientation of head-controller was calculated through a convenient method. The advantage of this control scheme is that the head of the underwater snake-like robot remains in the forward direction during swimming. To prove the feasibility of the proposed methodology,two basic motion patterns,swimming along the straight line and swimming along the curved path,had been implemented in our simulation platform. The results showed that the simulation platform can imitate the swimming of the underwater snake-like robot and the head of the underwater snake-like robot remains in a fixed orientation directed towards the target. The oscillation of head's orientation is inhibited effectively.
基金the Natural Science Foundation of China(51175494,61128008)Newton Research Collaboration Programme(NRCP/1415/89)
文摘Marvi et al(Science,2014,vol.346,p.224)concluded a sidewinder rattlesnake increases the body contact length with the sand when granular incline angle increases.They also claimed the same principle should work on robotic snake too.We have evidence to prove that this conclusion is only partial in describing the snake body-sand interaction.There should be three phases that fully represent the snake locomotion behaviors during ascent of sandy slopes,namely lifting,descending,and ceasing.The snake body-sand interaction during the descending and ceasing phases helps with the climbing while such interaction during the lifting phase in fact contributes resistance.
基金Supported by the National Natural Science Foundation of China(No.61333016)
文摘A MNSM( mirror neuron system mechanism)-based controller is developed to present the swimming rhythm of a snake-like robot in Cartesian space. From engineering viewpoint,the proposed controller is composed of a neuron for rhythm angle and two neurons for motion knowledge in XY plane. The given knowledge is a rhythm curve for swimming motion of a snake-like robot. Experimental results show that the proposed controller can present the knowledge of swimming rhythm,which represents the corresponding control law to drive the snake-like robot to swim with different speeds and turning motion. This work provides a novel method to present the knowledge for swimming motion of snake-like robots.
基金Sponsored by the National Nature Science Foundation of China(Grant No.51009091)the Special Research Fund for the Doctoral Program of Higher Education(Grant No.20100073120016)
文摘In prior research,the orientation of head of the snake-like robot is changed according to the sinusoidal wave. To solve this problem,we propose Central Pattern Generator( CPG)-based control scheme with head-controller to stabilize the head of the underwater snake-like robot. The advantage of the CPG-based control scheme with head-controller is that the head of the underwater snake-like robot is direct to the target orientation during swimming. The relation between CPG parameters and orientation stability of head is discussed.The adaptation of the proposed method to environment changes is tested. The influences of CPG parameters and hydrodynamic forces on the orientation offset of head are investigated. The target orientation( the input of headcontroller) with an experimental optimization is calculated through a convenient method. To prove the feasibility of the proposed methodology,the different swimming modes have been implemented in our simulation platform.The results show that the oscillation of head's orientation is inhibited effectively,and the proposed method has strong adaptation to environment and CPG parameters changes.
文摘From a bionics viewpoint , this paper proposes a mechanical model of a wheeled snake like mobile mechanism. On the hypothesis of the existing non holonomic constraints on the robot kinematics, we set up the relationship among the kinetic control parameters in the snake like movement using Lie group and Lie algebra of the principle fiber bundle and provide some theoretical control methods to realize the snake like locomotion.
