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This paper proposes repeatedly direct kinematics (RDK) algorithm to trajectory generation of a multi-joint robot in lift-down movements. For trajectory generation of the multi-joint robot, three constraints are considered. They are no turnover, the joint limits and the torque limits of the robot. Safety factor is set in order to ensure the stability of robot. The emphasis of the study is placed on...
This work proposes a way to make a group of mobile robots which are navigating as a formation to avoid obstacles in their paths. A trajectory tracking controller is proposed to guide the robots during the navigation, to which an obstacle deviation subsystem is added. Such subsystem is implemented in each robot in the formation, whereas the proposed controller is applicable to subsets of three robots...
The formation control problem of mobile multiple robots is investigated. A formation control scheme based on a hierarchical virtual structure is proposed. The mobile robots are divided into some clusters according to their distributions in space and then the motion trajectory of every cluster (virtual structure) is defined, so the motion of virtual structure is transformed to desired trajectory of...
A moving-target-enclosing problem is investigated in the paper, where the velocity of the target is unknown and the neighbor topologies may change over time. Each robot only uses the relative position information of the target and its neighbors that may dynamically change over time. An adaptive scheme is proposed to estimate the velocity of the target. Then a distributed control law for each robot...
This work implements a visual-servo control that generates motor commands for a mobile robot according to a visual target. This robot is also the leader of a robot team that uses a centralized, non-linear and stable control to keep group formation. Therefore, whenever the target moves, the leader moves to correct its position and orientation, also forcing the whole team to move in formation. The combination...
This paper proposes novel formation maintenance strategies for multiple nonholonomic mobile robots based on nonholonomic trajectory tracking techniques and dynamic feedback linearization. It also presents experimental results for formation stability and noise tolerance of the proposed and existing leader-follower based controllers using physical P3AT robots. The research focusses only on the problem...
The paper presents a method for decentralized flocking and global formation stabilization for a network of unicycles described by the standard kinematics equations with hard constraints on the vehicles linear and angular velocities.
A unified formation control policy is presented. From the trajectory and shape aspects, the group formation control problem is decoupled into the desired trajectory tracking problem of each individual, and the consistency of stability and optimality between these two problems are proved. The overall criterion and decomposed criterions to evaluate the formation performance are designed. The decomposed...
Formation control in uncertain environment is studied, including the control process noise and measurement noise. The decoupled Kalman filter based on discrete model is established. And the control performances based on absolute positioning sensor, relative positioning sensor or fusion of these two kinds of sensor are studied. Simulations show that absolute positioning sensor could assure the formation...
We define a leader-follower flocking system in which a few members are group leaders who have global trajectory knowledge, while majority members are group followers who can communicate with neighbors, but do not have global trajectory information. The followers even do not know who are the leaders in the group. All group members estimate the position of flocking center by using a consensus algorithm...
This paper presents a multi-layer scheme to control a formation of n mobile robots, including a strategy for obstacle avoidance. The controller adopted is able to guide the robots to compose the desired formation and to track a desired trajectory, avoiding obstacles during the navigation. Two planning layers are responsible for organizing the navigation of the individual robots towards the desired...
For N unicycles moving in formation, a cooperative control strategy for target capturing including the steering angle regulation problem is proposed in this paper. The stabilizing method is based on LaSallepsilas invariance principle and ensures, in the 2D space, the target capturing. The method does not require motion planning. Hence, the convergence to the desired attractive set surrounding the...
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