In this paper the modeling and observation of elastic robot joints with hysteresis is addressed. An adequate model of the joint torque transmission which could capture the hysteresis lost motion is of outstanding inte...
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In this paper the modeling and observation of elastic robot joints with hysteresis is addressed. An adequate model of the joint torque transmission which could capture the hysteresis lost motion is of outstanding interest for design and control of flexible joint robots. A method of describing the significant joint nonlinearities such as dynamic friction and state-dependent stiffness with hysteresis is proposed. The joint dynamics is considered as an interplay between the propulsion and reactive torque. Direct and inverse hysteresis models of state-variant joint stiffness are introduced and identified from experiments. The proposed joint torque observer can serve as a “virtual” sensor of hysteresis lost motion without measuring the joint output.
The paper provides an overview on the 6-DOF robot manipulator for control education and research at a robotic lab at TU-Dortmund. The Matlab-based framework for a safe and reliable remote operation of a standard indus...
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The paper provides an overview on the 6-DOF robot manipulator for control education and research at a robotic lab at TU-Dortmund. The Matlab-based framework for a safe and reliable remote operation of a standard industrial robotic manipulator enables students and researchers to conduct experiments in robotics and control in efficient and productive manner. In addition to an overview of the robot and the control framework the paper reports on the experiments of several student theses and project groups conducted in the past few years. The outlook sketches some challenges and perspectives for future utilization of the control framework in the context of students education and research.
This article considers robust model predictive control (MPC) schemes for linear parameter varying (LPV) systems in which the time-varying parameter is assumed to be measured online and exploited for feedback. A closed...
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This article considers robust model predictive control (MPC) schemes for linear parameter varying (LPV) systems in which the time-varying parameter is assumed to be measured online and exploited for feedback. A closed-loop MPC with a parameter-dependent control law is proposed first. The parameter-dependent control law reduces conservativeness of the existing results with a static control law at the cost of higher computational burden. Furthermore, an MPC scheme with prediction horizon '1' is proposed to deal with the case of asymmetric constraints. Both approaches guarantee recursive feasibility and closed-loop stability if the considered optimisation problem is feasible at the initial time instant. [PUBLICATION ABSTRACT]
We present an approach to synthesize the terminal control law and the terminal set of nonlinear model predictive control with guaranteed ℒ 2 performance, where a structured feedback uncertainty is considered. The ter...
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We present an approach to synthesize the terminal control law and the terminal set of nonlinear model predictive control with guaranteed ℒ 2 performance, where a structured feedback uncertainty is considered. The terminal control law, which is obtained through the solution to a Hamilton-Jacobi-Bellman-Isaacs (HJBI) inequality of the Jacobian linearization of the original nonlinear system, renders the uncertain nonlinear system robust invariant in the terminal set.
This paper proposes a supervisory control structure for networked systems with time-varying delays. The control structure, in which a supervisor triggers the most appropriate controller from a multi-controller unit, a...
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We consider a controllable linear time invariant model in state space of dimension n which might be the Jacobian linearization of a nonlinear model. Alternatively it may arise from a preceding input-output or input-st...
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We consider a controllable linear time invariant model in state space of dimension n which might be the Jacobian linearization of a nonlinear model. Alternatively it may arise from a preceding input-output or input-state linearization. The usual objective for such systems is to stabilize an equilibrium. However, it might as well be interesting to have a stable limit cycle around the equilibrium. So far, limit cycles are often studied in the context of nonsmooth dynamics. In contrast, our approach results in a smooth and simple feedback. The first step is to impose a pair of purely imaginary eigenvalues to the system while the second one is to construct a bilinear form with which the resulting oscillations can be stabilized at a given amplitude.
A novel robust tracking control technique for time-delay systems with uncertain time-delays based on fuzzy T-S is presented. Fuzzy T-S model with parametric uncertainties is employed to represent the uncertain time-de...
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This paper deals with high gain observer design for Lipschitz nonlinear systems. High gain observers are very popular in applications because of their simple implementation with a constant observer gain. In practice, ...
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This paper deals with high gain observer design for Lipschitz nonlinear systems. High gain observers are very popular in applications because of their simple implementation with a constant observer gain. In practice, the gain is usually chosen based on eigenvalue placement sufficiently far in the complex left half-plane, where the convergence of the nonlinear observer is verified by simulation. Although this strategy works well in many applications, the exact choice of the observer gain is more complicated. In particular, existing design methods often result in a severe restriction of the maximum allowed Lipschitz constant. In many cases, these bounds on the Lipschitz constant are very conservative. We will show that the maximum admissible Lipschitz constant can be increased significantly if the structure of the system is taken into consideration.
An approach for trajectory optimization for vehicles maneuvering in a constrained environment is developed. Within this framework, a benchmark problem, the minimimzation of the transit time of a point mass vehicle thr...
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ISBN:
(纸本)9781467320658
An approach for trajectory optimization for vehicles maneuvering in a constrained environment is developed. Within this framework, a benchmark problem, the minimimzation of the transit time of a point mass vehicle through a chicane is proposed. This problem is solved using the projection operator Newton method with barrier functions to manage the acceleration and roadwidth constraints. The numerical solution of the benchmark problem is analyzed in detail as is the characteristics of the solution itself.
An innovated investigation of the control problem for nonlinear discrete-time plant systems via Takagi-Sugeno fuzzy model was carried out. Firstly, nonlinear dynamic plants are represented by such a fuzzy model, and t...
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