The Infona portal uses cookies, i.e. strings of text saved by a browser on the user's device. The portal can access those files and use them to remember the user's data, such as their chosen settings (screen view, interface language, etc.), or their login data. By using the Infona portal the user accepts automatic saving and using this information for portal operation purposes. More information on the subject can be found in the Privacy Policy and Terms of Service. By closing this window the user confirms that they have read the information on cookie usage, and they accept the privacy policy and the way cookies are used by the portal. You can change the cookie settings in your browser.
An improved Gauss pseudospectral method with linear final state constraints is proposed to solve the trajectory optimization problem of free-floating space manipulator (FFSM) system. In this paper, the problem is transformed into a nonlinear programming problem (NLP) by states approximation at the Legendre-Gauss (LG) points and the boundary times. The differential of these states can be expressed...
In this article a new method for planning smooth and time-optimal trajectories for robot manipulators is proposed. Trajectory planning is considered as dynamic optimization problem in which the end-effector path as well as the limitations of the joint velocities, the actuator torques and the actuator torque rates are the constraints. These constraints transferred to the space of the path variable...
This paper presents a methodology for trajectory control of single-link lightweight flexible manipulators. The objective is to control the trajectory of the tip position of the flexible-link manipulator in the presence of joint friction and output disturbances. Robust nonlinear approach is applied to guarantee system stability and to alleviate the degrading effects of uncertainties and nonlinearities...
As described in this paper, we specifically examine a point-to-point motion task of a rigid robot manipulator attached to a flexible link and present an optimal trajectory planning technique for suppressing residual vibrations of the flexible link. Soft computing methods are used in the trajectory planning method, in which radial basis function networks and a particle swarm optimization algorithm...
The aim of this paper is to design a neural network (NN) based motion/force control scheme for holonomic constrained nonholonomic mobile manipulators with model uncertainties and external disturbances. For compensator design, the prior knowledge of the bound of uncertainty is not required but we estimate this bound by using feedforward neural network. The constraint force converge to the desired force...
In determining the maximum dynamic load-carrying capacity (DLCC) of reconfigurable motor-driven parallel kinematic manipulators (PKM), the objective is to identify the optimal configuration which accomplishes the assigned motion for the maximum DLCC subject to the constraints imposed by the kinematics and dynamics of the manipulator structure. In this study, the maximum DLCC problem of a reconfigurable...
The active disturbance rejection control (ADRC) for high-precision trajectory tracking of manipulator flexible joint is researched. The dynamics model with friction and uncertainties external disturbances of system is established. In order to study the effect and compensation of friction, a dynamic LuGre friction model is introduced. A control strategy of the inner and outer loops control using ADRC...
A robotic heart motion simulator (HMS) is developed at DLR (German Aerospace Center) to accurately simulate real translational motions of a mechanically stabilized beating heart in a lab environment. This simulator is part of the DLR scenario for motion compensation on the beating heart. Motion compensation is a highly desired issue in minimally invasive surgery. The design of the HMS as well as its...
This paper investigates a passivity-based control for two degree of freedom(2DOF) robot manipulators with antagonistic bi-articular muscles which are passing over adjacent two joints and acting the both joints simultaneously. The manipulator dynamics of three muscle torques, we call the bi-articular manipulator dynamics, is constructed in order to design the control input. Stability analysis with...
While the robot passes through the singular configuration, small motion within the working space will cause the joint velocity to tend to infinity and then result in the robot out of control. In order to solve the problem, the issue on trajectory control for six-DOF-joint robot to pass through singular configuration was studied in this paper and a new control mode was put forward. By using line geometry...
Space exploitation will require efficient techniques for manipulating passive objects on-orbit. This work presents a manipulation technique that utilizes both on-off thrusters and manipulator proportional forces to handle passive objects on orbit, canceling the effect of limit cycles on the objects. The system dynamics including the unilateral constraints and the on-off thrusting are discussed. Using...
This paper presents a new adaptive controller for visual tracking control of a robot manipulator in 3D general motion with a fixed camera whose intrinsic and extrinsic parameters are uncalibrated. In addition to camera parameters, the feature positions in 3D space are also assumed unknown. Based on the fact that the unknown parameters appears linearly in the closed-loop dynamics of the system if the...
Operational space control has a number of desirable characteristics but is sensitive to model accuracy. For heavy machines the dynamics are difficult to model due to their friction and dynamic coupling, thus making full compensation imprecise. This work presents an approach in which a simplified model gives partial compensation via an open-loop feedforward input, pre-calculated in forward simulation...
A novel six-DOF parallel manipulator is introduced. Kinematics analysis is discussed and using Lagrange equations for constrained systems the full dynamic modeling is performed. Sliding mode control as a class of very special nonlinear control is proposed to control the position of the manipulator in the presence of parametric uncertainties. Stability of the system is guaranteed via Lyapunov approach...
A robot manipulator is expected to play an important role in the production process of plastic factory. A sliding mode controller is present for a 4-DOF injection molding machines take-out manipulator. The dynamic model of the manipulator has been built, and the stability of the control system is analyzed with the Lyapunov theory. The simulation experiment about the desired position trajectory tracking...
In this paper, one of the possibilities of introduction of variable stiffness in a rehabilitation manipulator for lower limbs, is described. Mechanical design and working principle of a proposed system are presented. The following control algorithms for manipulators with flexible joints are suggested: the position control and the active impedance control. The tracking performance is experimentally...
The interest in novel engineering methods and tools for optimizing the energy consumption in robotic systems is currently increasing. In particular, from an industry point of view, it is desirable to develop energy saving strategies applicable also to established manufacturing systems, being liable of small possibilities for adjustments. Within this scenario, an engineering method is reported for...
This paper proposes an iterative learning control scheme for a redundant manipulator to acquire a skilled hand writing motion of its end-point specified on an arbitrary smooth surface. Firstly, the existence of a unique solution to the Lagrange equation of motion of the robot, whose end-point motion is coincident with a given desired end-point trajectory described in Cartesian coordinate system, is...
The modeling and vibration analysis of a flexible manipulator considering a nonlinearity and effect from the gravity imply a singular problem. In order to avoid the singularity, the dynamic equation is decomposed into two subsystems, including flexible dynamic subsystem and rigid dynamic subsystem. A combined feed-forward and feedback control scheme is presented to design the controller of the flexible...
The movement of autonomous agents in natural environments is restricted by potentially large numbers of constraints. To generate behavior that fulfills all given constraints simultaneously, the attractor dynamics approach to movement generation represents each constraint by a dynamical system with attractors or repellors at desired or undesired values of a relevant variable. These dynamical systems...
Set the date range to filter the displayed results. You can set a starting date, ending date or both. You can enter the dates manually or choose them from the calendar.