1,721,006 research outputs found
Second-order sliding-mode control of a mobile robot based on a harmonic potential field
No full textThe problem of controlling an autonomous wheeled vehicle which must move in its operative space and reach a prescribed goal point avoiding the collision with the obstacles is dealt with. To comply with the non- holonomic nature of the system, a gradient-tracking approach is followed, so that a reference velocity and orientation are suitably generated during the vehicle motion. To track such references, two control laws are designed by suitably transforming the system model into a couple of auxiliary second-order uncertain systems, relying on which second-order sliding modes can be enforced. As a result, the control objective is attained by means of a continuous control law, so that the problems due to the so-called chattering effect, such as the possible actuators wear or the induction of vibrations, typically associated with the use of sliding-mode control, are circumvented
Sliding mode control of a mobile robot for dynamic obstacle avoidance based on a time-varying harmonic potential field
No full textIn this paper, a harmonic potential field method for dynamic environments is proposed to generate an on-line reference trajectory for a wheeled mobile robot. A sliding mode controller is used to make the robot move along the prescribed trajectory determined by the gradient lines. The potential field is modified on-line, in order to make the robot avoid the collision with obstacles which move along non a-priori known trajectories with time-varying speed. The mechanism through which the field is modified is based on the so-called ‘collision cone’ concept
A sub-optimal second order sliding mode controller for systems with saturating actuators
No full textA dynamic obstacle avoidance strategy for a mobile robot based on sliding mode control
No full textIn this paper, a dynamic obstacle avoidance strategy for mobile robots is proposed. The strategy consists of two key elements: an on-line reference generator and a control scheme to make the robot track the reference signals so as to reach a pre-specified goal point. To generate the online reference signals, a harmonic potential field for dynamic environments is exploited. The potential field is modified on-line, in order to make the robot avoid the collision with obstacles which move along non a-priori known trajectories with timevarying speed. The proposed multi-level sliding mode controller is capable of making the robot move tracking the prescribed reference signals determined by the trajectory generator. The simulation results confirm the good performances of this approach
A Discrete-Time Integral Sliding Mode Control Law for Systems with Matched and Unmatched Disturbances
Full text linkThis letter proposes a discrete-time integral sliding mode (DT-ISM) control strategy for linear time-invariant systems subject to matched and unmatched disturbances. The DT-ISM strategy is defined based on a discrete-time model of the system obtained from its continuous-time counterpart, providing numerical procedures to determine the sets in which the disturbances are contained, starting from the corresponding sets in the continuous-time domain. The DT-ISM law is based on disturbance estimation to ideally steer the sliding variable to zero in one discrete step, and achieves a quasi-DT-ISM in the presence of bounded estimation errors. The effectiveness of the proposed control law is tested in simulation combined with a robust model predictive control law
Second order sliding mode control of a perturbed double integrator with state constraints
No full textThis paper introduces a second order sliding mode controller for double integrators subject to external disturbances and model uncertainties, with both control and state constraints. The proposed control strategy proves to be able to robustly steer the system state to zero in a finite time, fulfilling the state constraints in spite of the uncertainties, provided that the initial state is inside a given region. The effectiveness of the proposal is then tested on a simulation example
A sub-optimal second order sliding mode controller for systems with saturating actuators
No full textIn this paper, the problem of the possible saturation of the continuous control variable in the sub-optimal second order sliding mode controller applied to relative degree one systems with saturating actuators is addressed. It is proved that during the sliding phase, if basic assumptions are made, the continuous control variable never saturates, while, during the reaching phase, the presence of saturating actuators can make the steering of the sliding variable to zero in finite time not always guaranteed. In the present paper, the original algorithm is modified in order to solve this problem: a new strategy is proposed, which proves to be able to steer the sliding variable to zero in a finite time in spite of the presence of saturating actuators
Optimal disturbance rejection via integral sliding mode control for uncertain systems in regular form
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