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This paper presents a sliding mode hybrid impedance controller for complex interaction tasks. For easily implementing the scheme in embedded system, it is developed in discrete difference format. The hybrid impedance control is adopted since it is capable for both target impedance and force tracking. Then, the equivalent control based sliding mode control is introduced for robust to external disturbance...
Trajectory planning has been a common and important topic in robotics since its generation. As a powerful tool, it can enhance the performance of the robots in manufacturing industry. In this paper, a trajectory planning method based on unit quaternion was proposed. Unit quaternions were used to represent the orientations of the target as there are no more singularities. The trajectory was planning...
This paper presents a novel way to derive the analytical expression of the reaction torque acted on the satellite base's centroid firstly. The reaction torque is acted as the optimization index to achieve the satellite base disturbance minimization in this paper. The null-space based solution and Lagrange multipliers based solution are utilized to solve the reaction torque plus joint torque minimization...
Inverse kinematics is a general method for defining the joint angles of the robot arm. This method provides an efficient way to control the robot arm for several tasks. However, the server motors or the mechanism design of the robot arm may not always be ideal. If the motor consumption is existed, the error of the final position of the robot arm will be increased. In order to solve this problem, this...
This paper presents a multi-level speed planning based capturing strategy. A kind of widely used simultaneous three-fingered end-effectors is selected to conduct the capturing strategy research. The mechanical characteristics of the end-effector and the grapple process are analyzed first, followed by the dynamic model of the system. The capturing speed is planned with the information from the positional...
Continuum manipulators can exhibit behaviors similar to snakes, elephant's trunks, and octopus tentacles, which possess incredible dexterity and intrinsic compliance for safe interaction with unstructured environments. However, the lack of enough stiffness limits their scope and application. In this paper, we introduce four different structures of continuum manipulators, including a simple structure...
The main challenge of motion planning for a hyper-redundant manipulator is to implement a modular structure ensure real time and high performance of the control system. In this research, we present a strategy to deal with the motion planning problem of a hyper-redundant manipulator, include uncertain time delay to the control system and obstacle avoidance. Similarly to the principles of motor control...
The output of a six-axis force/torque sensor (F/T sensor) not only varies with force or torque but also is affected by ambient temperature. In order to check the effects of temperature drift on the measurement precision of the sensor, this paper carried out experiments to obtain the quantitative results without loading the force and torque. In detail, three methods, including the least square method,...
Narrow passages in changing environments create huge difficulties, since locations and shapes of narrow passages in Configuration Space(C-space) change frequently. It is very important for a planner to identify narrow passages in real time and boost valid points within them effectively. A novel narrow passage predictive model for designing a path planner in changing environments is proposed in this...
This paper describes a redundant resolution method for 7-DOF anthropomorphic manipulator with joint limits, which considers the optimization of human-like motion and the optimization of the maximum reachable region of the manipulator's tip. First, a novel method for computing the set of feasible arm angle under joint limits is presented. Second, a relation describing the movement characteristics of...
A space-saving end-effector is designed for small scale manipulator in this paper. The end-effector is equipped with capture and actuation transmission capabilities. Two subsystems are highly integrated systems of mechanics, electronics and sensors. A trefoil shaped capture system is developed for closed envelop. The worm shaft and worm wheels are adopted for the self-locking property, and they are...
In the paper, a new method named Cartesian Space Synchronous Impedance Control (CSSIC) has been developed. The method combines the synchronous control and the impedance control together which can not only be used in the position control but can also realize the purpose of force control of the system with multi-manipulators. Therefore, if there are multi-manipulators grasping the same object, it can...
A novel adaptive object impedance control strategy is presented for dual-arm cooperative humanoid manipulators. A general impedance scheme comprising internal impedance control and object impedance control is adopted, which aims at conferring a compliant behavior both in end-effector level and object lever. The adaptation law for the stiffness and damping of object impedance is derived from Lyapunov...
In this paper we propose a strictly conservative and novel hybrid safety control strategy consisting of the pre-contact safety strategy and the post-contact safety strategy in order to provide safety guarantees and enable continuous motions. An optimal motion trajectory planning that limits jerk, acceleration and velocity of robot motion and can obtain a time optimal motion is introduced as post-contact...
In this paper, a 7-DoF robot table tennis system is presented, which adopts a stereo vision system as its perceptional sensor and a humanoid robot arm as its manipulator. The batting policy, which can return various incoming balls to a desired location, is learned through empirical data based on e-support vector regression(e-SVR). Two experiments, playing with a launcher machine and rallying with...
In order to verify and test the dynamics characteristic of free-floating space robot, a hybrid dynamics simulation experiment based on hardware and software simulation is present in this paper. Firstly, a set of ground experiment system which consists of the joint electronic simulator, the central controller and dynamics simulation computer is built to simulate the motion of space manipulator and...
This paper developed a teleoperation system of a space robot, which can assist the operator in planning trajectory quickly and intuitively. In addition to the general function, this system can ensure the completion of certain mission when some joint of the space robot is locked for a hardware malfunction. The teleoperation system includes 4 subsystems-Graphics display subsystem, Camera monitor subsystem,...
A key technology of space robots is to maintain the satellite attitude while space service is proceeding. This paper discusses the motion planning and control methods for both robot satellite attitude and robotic end-effector actions in the form of collaboration. A single gimbal control moment gyro (SGCMG) system is adopted to maintain the satellite attitude because of higher output torque than traditional...
This paper presents a novel method to identify and boost difficult regions of in the configuration space (C-space) in changing environments. Difficult regions, especially narrow passages, change their shapes frequently in changing environments, which result in challenging problems to find valid and safe paths. Although a lot of research has been done to identify difficult regions, seldom methods provide...
This paper presents an overview of the structure and requirements of a ground engineering model for a space remote manipulator system, with long arm and large torque driver capacity. The system consists of a 6 DOFs robot arm composed of six identical modular joints, and a large-error tolerated end effector. A FPGA based joint controller hardware structure is built to form a distributed control scheme...
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