Shugen Ma

Coupled tendon-driven multijoint manipulator

A coupled tendon-driven manipulator called the CT arm is introduced, an its control is discussed. The CT arm has a specific tendon traction force transmission mechanism in which a pair of tendons for driving a joint are pulled from base actuators via pulleys mounted on the base-side joints. The mechanism makes the most of the coupled drive function of the tendon traction forces and thus can exhibit enormous payload capability. The CT arm is solidly structured and can be inexpensively manufactured because of its mechanical simplicity. A control algorithm which minimizes the square sum of the traction force of tendons while satisfying given restrictions is introduced. The validity of the control method is shown by computer simulation.<<ETX>>

Analysis of stairs-climbing ability for a tracked reconfigurable modular robot

Stairs-climbing ability is the crucial performance of mobile robot for urban environment mission such as urban search and rescue or urban reconnaissance. The track type mobile mechanism has been widely applied for its advantages such as high stability, easy to control, low terrain pressure, and continuous drive. Stairs-climbing is a complicated process for a tracked mobile robot under kinematics and dynamics constraints. In this paper, the stairs-climbing process has been divided into riser climbing, riser crossing, and nose line climbing. During each climbing process, robots mobility has been analyzed for its kinematics and dynamics factor. The track velocity and accelerations influences on riser climbing have been analyzed. And the semiempirical design method of the track grouser and the module length has been provided in riser crossing and nose line climbing correspondingly. Finally, stairs-climbing experiments have been made on the two-module robot in line type, and three-module robot in line type and in triangle type respectively.

Omnidirectional static walking of a quadruped robot

In this paper, we propose a successive gait-transition method for a quadruped robot to realize omnidirectional static walking. The gait transition is successively performed among the crawl gaits and the rotation gaits, while the feet hold in common positions before and after gait transition. The gait-transition time is reduced by carefully designing the foot positions of the crawl gait and the rotation gait, while limiting the feet in rectangular reachable motion ranges. Computer simulations and experiments were executed to show the validity and the limitation of the proposed gait-transition method.

Design and experiments for a coupled tendon-driven manipulator

The authors describe the operation of a tendon-driven manipulator, the CT ARM-I, which has a tendon traction force transmission mechanism in which the pair of tendons that drive a joint are pulled from base actuators via pulleys mounted on the base-side joints. The mechanism makes the most of the coupled drive function of the tendon traction forces and thus enables the lightweight manipulator to exhibit enormous payload capability. The manipulator has a solid structure and is inexpensive to manufacture because of its mechanical simplicity. Experiments demonstrate that the CT ARM-I has an active compliance arm and offers payload capability superior to that of conventional manipulators.<<ETX>>

Turning and side motion of snake-like robot

With high adaptability to environments snakelike robots offer a variety of advantages over other mobile robots. Such a robot with passive wheels has quite different mechanism in locomotion from that of other locomotion systems. We have developed a snakelike robot for rescue applications. The unit composing the snakelike robot of Shenyang Institute of Automation (SIA) is a module including actuating system and control system. To let the snakelike robot perform turning motion and compensate offset and orientation errors of the robot, we propose an amplitude modulation method and a phase modulation method based on analysis of the serpenoid curve. The side motion of the snakelike robot can also be generated by the amplitude modulation. The tracking control method is also proposed based on sensor information. Computer simulations and experimental tests are performed to show the validity of the proposed methods.

Development of a hyper-redundant multijoint manipulator for maintenance of nuclear reactors

A tendon-driven manipulator, the CT Arm, has a specific tendon traction transmission mechanism, in which a pair of tendons for driving a joint is pulled from base actuators via pulleys mounted on the based-side joints. The mechanism makes the most of the coupled drive function of the tendon tractions and thus enables the lightweight manipulator to exhibit enormous payload capability. By this tendon-driven mechanism, a multijoint manipulator with super-redundant degrees of freedom could be realized, which is suitable to the maintenance of nuclear reactors. In this article, we introduce the CT Arm and discuss the possibility of generating a multijoint maintenance manipulator for nuclear reactors, which must have super-redundant degrees of freedom. A position-coordination approach for a hyper-redundant manipulator to carry tools or inspection equipment passing through a hole to a work location in a nuclear reactor is also proposed. Computer simulation has been used to show the validity of the hyper-redundant...

Intelligent mobile manipulator navigation using adaptive neuro-fuzzy systems

The work presented in this paper deals with the problem of autonomous and intelligent navigation of mobile manipulator, where the unavailability of a complete mathematical model of robot systems and uncertainties of sensor data make the used of approximate reasoning to the design of autonomous motion control very attractive. A modular fuzzy navigation method in changing and dynamic unstructured environments has been developed. For a manipulator arm, we apply the robust adaptive fuzzy reactive motion planning developed in [J.B. Mbede, X. Huang, M. Wang, Robust neuro-fuzzy sensor-based motion control among dynamic obstacles for robot manipulators, IEEE Transactions on Fuzzy Systems 11 (2) (2003) 249-261]. But for the vehicle platform, we combine the advantages of probabilistic roadmap as global planner and fuzzy reactive based on idea of elastic band. This fuzzy local planner based on a computational efficient processing scheme maintains a permanent flexible path between two nodes in network generated by a probabilistic roadmap approach. In order to consider the compatibility of stabilization, mobilization and manipulation, we add the input of system stability in vehicle fuzzy navigation so that the mobile manipulator can avoid stably unknown and/or dynamic obstacles. The purpose of an integration of robust controller and modified Elman neural network (MENN) is to deal with uncertainties, which can be translated in the output membership functions of fuzzy systems.

Serpentine locomotion of a snake-like robot controlled by cyclic inhibitory CPG model

Based on the structure of both biological snakes and snake-like robots and their rhythm locomotion, the theory of the cyclic inhibitory CPG is adopted as a control method to construct a neuron network model of the snake-like robot. The relation between the CPG parameters and the serpentine locomotion of the snake-like robot is defined in this paper. The validity of the serpentine locomotion controlled by the CPG model is verified through a snake-like robot model. The modulating methods of the CPG parameters are brought forward and simulated to realize the required turn motion and the reconfiguration. Moreover, we present that real snake-like robot can successfully exhibit serpentine locomotion by using controller output of the proposed architecture. Finally, the aspects of future researches are discussed.

Analysis of Creeping Locomotion of a Snake-like Robot on a Slope

The diverse locomotion modes and physiology of biological snakes make them supremely adapted for their environment. To model the noteworthy features of these snakes we have developed a snake-like robot that has no forward direction driving force. In order to enhance the ability of our robot to adapt to the environment, in this study we investigate the creeping locomotion of a snake-like robot on a slope. A computer simulator is presented for analysis of the creeping locomotion of the snake-like robot on a slope, and the environmentally-adaptable body shape for our robot is also derived through this simulator.

Redundancy decomposition control for multi-joint manipulator

A control method called redundancy decomposition control is proposed for the resolved acceleration control of a manipulator equipped with redundant degrees of freedom. In this method, the redundant degrees of freedom of a given manipulator are decomposed into nonredundant subsets. For every time interval from t to t+ Delta t, the acceleration of the corresponding subset of degrees of freedom is assumed to be controlled and the inverse kinematics and dynamics as well as the evaluation function are calculated using the nonredundant inverse Jacobian matrix. The calculation is performed in parallel for all the combinations of degrees of freedom. The optimum set of degrees of freedom is selected and it is used for the control of the time interval t to t+ Delta t. The proposed method is reviewed in comparison with conventional approaches, including the pseudoinverse matrix and null-space vector techniques. It is demonstrated that the proposed method almost always realizes better motion planning than the other two techniques, and is effective in real-time control.<<ETX>>