Fuhai Zhang

Bio: Fuhai Zhang is an academic researcher from Harbin Institute of Technology. The author has contributed to research in topics: Spacecraft & Kinematics. The author has an hindex of 2, co-authored 4 publications receiving 9 citations.

A dynamic control method for free-floating space manipulator in task space

Abstract: A dynamic control approach in task space is proposed for trajectory tracking problem of free-floating space manipulator without controlling the pose of the spacecraft. Based on the extended manipulator model, the dynamic equation of the system is derived. The dynamic parameters needed by the dynamic control in task space could be estimated by the off-line adaptive identification method. The presented control scheme guarantees asymptotic tracking of the desired end-effector trajectory and does not require measurement of the joint accelerations. Simulation results given show the feasibility and effectiveness of the proposed method.

Dynamic simulation and analysis for bolt and nut mating of dual arm robot

Abstract: Dual arm cooperative robots have been developed in diverse fields A dual arm robot is more advantageous than the single arm version The difficulty in mechanical analysis for dual arms comes mainly from the closed chain system To overcome this problem, the kinematic analysis of dual arm robot is introduced, including kinematic analysis of closed chain and the arms The kinematic constraint relations for bolt and nut mating of dual arm robot are analyzed By using the constraint relations, the bolt and nut mating simulation is performed on the 3D model of the dual arm robot Simulation results show that this method can make the dual arm robot complete bolt and nut mating smoothly

Kinematics and simulations of space manipulator in three work modes

Abstract: In recent years, research on space robotics has attracted considerable attention. Kinematics of the free-flying or free-floating space manipulator system, including a spacecraft and a manipulator mounted on the spacecraft, is a significant problem. In free-floating work mode, the spacecraft will move freely in response to the disturbances caused by the manipulator motions. From the view of application, change of the spacecraft attitude for the space manipulator system is not desirable. Therefore, it is of significance to adopt the free-floating with zero-disturbance spacecraft attitude work mode. This paper presents an overview of the kinematics of the space manipulator system. Position and velocity kinematics solutions in three work modes are analyzed. The kinematics differences among the three work modes are formulated. The simulation results validate the effectiveness of the kinematics solutions in the three work modes.

Real-Time Trajectory Generation Methods for Cooperating Mobile Manipulators Subject to State and Control Constraints

Abstract: This paper deals with the real-time trajectory generation problem for two cooperating mobile robots moving the common rigid object. The holonomic constraints resulting from a closed kinematic chain and the dynamics of such a system are considered. Two methods of generation sub-optimal trajectories allowing for mechanical and control limitations and collision avoidance conditions are proposed. The first solution is based on a leader-follower approach, in the second one the robotic system is treated as a whole mechanism. In both cases, the trajectories are generated in order to avoid singularities and they are scaled to satisfy control constraints. Advantages and disadvantages of both presented approaches are discussed. A computer example involving two mobile manipulators consisting of nonholonomic platform (2,0) class and planar 3-DOF holonomic manipulator is presented.

Robust Adaptive Control of a Free-floating Space Robot System in Cartesian Space

Abstract: This paper presents a novel, robust, adaptive trajectory-tracking control scheme for the free-floating space robot system in Cartesian space. The dynamic equation of the free-floating space robot system in Cartesian space is derived from the augmented variable method. The proposed basic robust adaptive controller is able to deal with parametric and non-parametric uncertainties simultaneously. Another advantage of the control scheme is that the known and unknown external disturbance bounds can be considered using a modification of the parameter-estimation law. In addition, three cases are certified to achieve robustness for both parametric uncertainties and external disturbances. The simulation results show that the control scheme can ensure stable tracking of the desired trajectory of the end-effector.

Neural network robust controllers applied to free-floating space manipulators in task space

Abstract: This paper deals with the problem of robust trajectory tracking control for free-floating manipulator systems subject to plant uncertainties and external disturbances. The system model is described through the Dynamically Equivalent Manipulator approach and the tracking problem is formulated directly in task space. Two adaptive techniques are developed considering nonlinear ℋ ∞ controllers and artificial neural networks. Experimental results are obtained from an underactuated three-link fixed-base planar manipulator dynamically equivalent to a two-link free-floating planar space manipulator.