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In this paper, we present a mid-level collision avoidance algorithm for autonomous surface vehicles (ASVs) based on model predictive control (MPC) using nonlinear programming. The algorithm enables avoidance of both static and moving obstacles, and following of a desired nominal trajectory if there is no danger of collision. We compare two alternative objective functions, where one is a quadratic...
This paper introduces a cable-driven robot for upper-limb rehabilitation. Kinematic and dynamic of this rehabilitation robot is analyzed. A sliding mode controller combined with a nonlinear disturbance observer is proposed to control this robot in the presence of disturbances. Simulation is carried out to prove the effectiveness of the proposed control scheme, and the results of the proposed controller...
This work addresses the problem of kinematic trajectory planning for mobile manipulators with non-holonomic constraints, and holonomic operational-space tracking constraints. We obtain whole-body trajectories and time-varying kinematic feedback controllers by solving a Constrained Sequential Linear Quadratic Optimal Control problem. The employed algorithm features high efficiency through a continuous-time...
In this paper, a trajectory generation algorithm within an integrated flight guidance and control system is presented. The approach uses clothoids to deal with the problem of curvature steps during the transition phase between straight line and arc flight. The algorithm is designed in interaction with a trajectory controller for 2nd order error dynamics, which hence requires more trajectory information...
In this work, we consider the labeled multi-robot planning problem. In this paradigm, a team of robots at fixed start positions must navigate to pre-specified and noninterchangable goal positions. While many algorithms have been proposed for finding optimal solutions to this problem, most methods assume that the robots are kinematic agents, whereas in reality, robots often have high-order dynamics...
This paper presents a Lyapunov based cooperative hunting method for multiple robots. First, the relative dynamics is obtained from the robot-target relative kinematics. Then, using the relative dynamics and dynamics of all the robots, a Lyapunov based local controller is derived to stabilize individual robots. Afterward, the cooperative control law is obtained by adding an extra term to the local...
This paper compares three different control methods of quadrocopters: linear-quadratic regulator, the method of inverse dynamics and full state feedback. The aim of this paper is to compare examined methods of control in respect of quadrocopter's energy consumption and accuracy of obtained trajectories. We evaluate efficiency of these methods, based on an example of quadrocopter's motion along an...
In the paper new control algorithm for skid-steering mobile platforms has been presented. This control law is based on mathematical model of such object. In the model it has been assumed that wheels of the skid-steering platform are not coupled by tracks and that they can move without some slipping effects, namely with lack of longitudinal slipping of selected wheels and lack of lateral slipping of...
This paper uses Sequential Action Control (SAC), a model-based method for control of non-linear systems, for fast, optimal trajectory-tracking tasks in the presence of fluid drift. Through the benchmark example of the kinematic car, it is shown that SAC outperforms a traditional offline projection - based optimization technique in terms of control effort and objective cost. Motivated by recent work...
A simple strategy to saturate the reference velocities when guiding an Unmanned Aerial Vehicle (UAV) to accomplish trajectory-tracking tasks is proposed. Such a controller has two parts: a kinematic controller to generate reference velocities for the vehicle and a state-variables change with a PD controller to guarantee the tracking of such velocities. This characterizes a cascade controller and guarantees...
Construct the tree efficient kinematics model based on broken branches action and how to change the trajectory with other branches after collision. This paper calculates collision force, after the collision velocity, and angle by the characteristics of collision mechanics, according to the relationship between the external force and gravity actually exist in nature. And then it constructs the kinematics...
The present paper presents a trajectory generation approach for a nonlinear dynamic inversion controller using second order error dynamics. The trajectory generation module provides an approach for 3D-trajectories with speed contraints including the determination of the trajectory reference point, the relative kinematics and the determination of the first derivatives of the deviation between unmanned...
This paper reformulates an optimization algorithm previously presented in continuous-time to one using structured integration and structured linearization methods from discrete mechanics. The objective is to synthesize trajectories for dynamic robotic systems that improve the estimation of model parameters by using a metric on Fisher information in a nonlinear projection-based trajectory optimization...
Kinematic planning for robotic arms has been shown to be capable of planning for robust manipulation of static objects. However, this approach falls short when manipulating moving objects such as picking up a jar off of a conveyor belt at a bottling plant. The challenge in carefully picking up moving objects is that these actions require motions that do not involve large decelerations, to avoid jerking...
This paper presents a kinematic control scheme for robot manipulators based on an algorithm that dynamically estimates an inverse of the Jacobian matrix. An interesting property of this algorithm is its ability to deal with the problem of kinematic singularities. The output of the algorithm can be interpreted as the filtered inverse of the Jacobian matrix. A case study of a 3-DoF non-redundant manipulator...
There are many applications where topology constraints are useful in trajectory generation for mobile robots. In this paper we present a method to generate an optimal trajectory restricted to a particular homology class. The optimality is achieved by formulating the trajectory generation problem as a Mixed-Integer Quadratic Program (MIQP). We introduce binary variables that not only encode information...
Planning collision-free, dynamically-balanced movements for humanoid robots is a challenging problem. An effective approach consists of first planning a motion satisfying geometric and kinematic constraints (such as collision avoidance, joint angle limits, velocity limits, etc.) and, in a second stage, modifying this motion so that it respects dynamic balance criteria, such as those relative to the...
This paper discusses a balance control method with kinodynamic constraints for leg-wheel hybrid structures in an effort to improve the mobility of locomotion over hard, flat surfaces. Preliminarily, we defined a prioritized Jacobian and a prioritized inverse of Jacobian to formulate the dynamically decoupled model in the task space for the constrained multi-contact multi-rigid-body system with a floating...
The paper deals with the motion planning for a spherical rolling robot actuated by internal rotors that are placed on orthogonal axes. It is shown that if the robot is actuated by three rotors, any feasible kinematic trajectory is dynamically realizable. For the case of two rotors the conditions of controllability and dynamic realizability of a feasible kinematic trajectory are established. It is...
The underactuated system under consideration is a magnetically-suspended, differential drive robot utilizing a winch system to articulate a suspended mass. A dynamic model of the system is first constructed, and then a nonlinear, infinite-dimensional optimization algorithm is presented. The system model uses the principles of kinematic reduction to produce a mixed kinematic-dynamic model that isolates...
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