1,720,979 research outputs found
Tracking control via switched Integral Sliding Mode with application to robot manipulators
No full textThis paper presents a switching structure scheme for motion control of industrial robot manipulators. To overcome the issues deriving from choosing a priori a specific control scheme, which can result in limited performances when the operating condition of the system varies, the scheme implements both a decentralized approach, suited for lower performance requirements and high transmission ratios, and the inverse dynamics based centralized approach, suited for higher performances in terms of velocity and acceleration. In both cases, the Integral Sliding Mode algorithm is used to compensate matched disturbances and to estimate the unmodeled dynamics used for the switching decision mechanism
Event-triggered variable structure control
No full textThis paper presents a novel variable structure control (VSC) algorithm of event-triggered (ET) type, capable of dealing with a class of nonlinear uncertain systems. By virtue of its ET nature, the algorithm can be used as the kernel of a robust networked control system. The design objective is indeed to reduce the number of transmissions over the network. The proposed ET-VSC also guarantees appropriate robustness properties, even in the presence of delayed transmissions. It is theoretically analysed, proving that the sliding variable associated with the controlled system results in being ultimately confined into a boundary layer of prescribed amplitude. As a consequence, it is proved that the state of the considered uncertain nonlinear system is ultimately bounded as well. Moreover, a lower bound for the time elapsed between consecutive triggering events is provided, which excludes the notorious Zeno behaviour. Finally, the designed ET-VSC control scheme is satisfactorily assessed in simulation
Predefined-time output stabilization with second order sliding mode generation
Full text linkIn this article, a novel second order sliding mode control strategy is proposed for relative-degree-2 nonlinear uncertain single- input-single-output (SISO) systems. To design the strategy, the phase portrait of the second order system in normal form associated with the formulated sliding mode control problem is studied. A sliding surface switching between arcs of parabolas is conceived to ensure the convergence in a predefined-time to the desired second order sliding mode. Lyapunov-based analysis and the reformulation of LaSalle-Yoshizawa results for nonsmooth systems are used to prove the uniform finite-time stability of the equilibrium consisting in the second order sliding mode enforcement. This in turn allows to prove the asymptotic convergence of the original plant state to the origin in spite of the uncertainties
A Leader-Follower Strategy with Distributed Consensus for the Coordinated Navigation of a Team of Quadrotors in an Environment with Obstacles
Full text linkThis paper proposes a novel strategy for the coordination of a team of quadrotor unmanned aerial vehicles (UAVs) that has to reach a target area, while moving in an environment with obstacles. The strategy consists of a coordi-nation phase, where the quadrotors assume a given formation, followed by a mission phase, where the UAV formation navigates to the target. In the latter phase, according to a leader-follower configuration, the leading agent receives from the ground station an obstacle-free trajectory to track, whereas the coordinated followers reconstruct and track their collision-free reference trajectories via a distributed consensus scheme. Finally, some simulation results are presented
Sliding mode fault diagnosis with vision in the loop for robot manipulators
No full textThis chapter is devoted to the problem of Fault Diagnosis (FD) for industrial robotic manipulators within the framework of sliding mode control theory. According to this control concept, a set of unknown input higher order sliding mode observers are designed to detect, isolate and identify multiple actuators faults and corruptions. More specifically, the whole FD architecture is based on the inverse dynamics-based feedback linearized robotic MIMO system, which is equivalent to a set of linearized decoupled SISO systems, affected by uncertain terms. The FD process includes a residual generation, followed by a decision making through the evaluation of the achieved residuals. The advantages of the sliding mode approach are the good performance in terms of stability and robustness, as well as satisfactory estimate of the occurring faults. Furthermore, in order to extend the FD strategy to multiple sensor and actuator faults, a low cost vision servoing architecture is used in the scheme, allowing one to design a fault tolerant control strategy in case of sensor faults. The effectiveness of the proposed FD architecture has been carried out in simulation on a realistic simulator as well as experimentally on a COMAU SMART3-S2 anthropomorphic robot manipulator
Switched adaptation strategies for integral sliding mode control: Theory and application
No full textIntegral sliding mode (SM) control is an interesting approach, as it can maintain the good chattering alleviation property of higher-order SMs while making the reaching phase less critical and keeping the controlled system trajectory on a suitably selected sliding manifold since the initial time instant. In order to make such a method more robust and to improve its flexibility by the adaptation of its parameters to the current system condition, in this paper, a switched strategy is proposed. Specifically, the suboptimal Second-order SM algorithm is considered as a basis in its integral formulation, and the switching strategy is designed by partitioning the so-called auxiliary system state space in a finite number of regions. The proposed method allows one to improve the transient performance by adapting the gains through these regions, thus implying an energy saving capability. The proposal is theoretically analyzed and, in order to test its performance, the control of the lateral dynamics of ground vehicles is used as a case study. Specifically, yaw-rate tracking is considered, as it is made difficult by parametric uncertainties and nonlinear effects that arise especially with large steering angles. Extensive simulation tests are carried out using standard validation maneuvers, which favorably witness the performance of the new control algorithm
Advanced and optimization based sliding mode control: theory and applications
Full text linkA compendium of the authors' recently published results, this book discusses sliding mode control of uncertain nonlinear systems, with a particular emphasis on advanced and optimization based algorithms. The authors survey classical sliding mode control theory and introduce four new methods of advanced sliding mode control. They analyze classical theory and advanced algorithms, with numerical results complementing the theoretical treatment. Case studies examine applications of the algorithms to complex robotics and power grid problems. Advanced and Optimization Based Sliding Mode Control: Theory and Applications is the first book to systematize the theory of optimization based higher order sliding mode control and illustrate advanced algorithms and their applications to real problems. It presents systematic treatment of event-triggered and model based event-triggered sliding mode control schemes, including schemes in combination with model predictive control, and presents adaptive algorithms as well as algorithms capable of dealing with state and input constraints. Additionally, the book includes simulations and experimental results obtained by applying the presented control strategies to real complex systems
A Configuration Space Reference Generation Approach for Real-Time Collision Avoidance of Industrial Robot Manipulators
No full textIn this work a novel approach for target reaching and collision avoidance in industrial robot manipulators is proposed. This method solely relies on the computation of the direct kinematics of the considered industrial manipulator in order to generate joint reference positions to perform real-time tracking in the operative space and avoidance of obstacles moving in the proximity of the robot. A comparison with a conventional model-based collision avoidance method has been carried out in a simulated industrial setting under different conditions, showing satisfactory results even in case of coarse sampling times. This makes the proposal suitable for filed real-time operations executed by industrial robots performing a task. The proposed approach has been deployed on the EPSON VT6 6-axis industrial manipulator, whose proprietary software has been interfaced with general-purpose robotic simulators in order to emulate complex and dynamic environments
A switching nonlinear MPC approach for ecodriving
Full text linkIn recent years many works focusing on improved vehicle fuel efficiency through advanced control have been carried out, reflecting the high interest in ecodriving of vehicles. Although many studies have shown the potential that optimal control based ecodriving can offer, these solution are often difficult to be translated into online control strategies, one of the reasons being the complexity of the optimal control problem and therefore the computational burden. To cope with this a novel online approach, based on switching Nonlinear Model Predictive Control (NMPC), is proposed. The NMPC strategy is developed for the case of conventional vehicles, where gear shifting and longitudinal dynamics are controlled. It is shown that our proposal can operate in real time, while recovering most of the performance achievable by an offline optimal solution. The development of the method is described in detail and its performance is analyzed. The results show that the proposed NMPC can successfully solve the ecodriving task and seems a good compromise between computational burden and performance suitable for field implementation
A Saturated Higher Order Sliding Mode Control Approach for DC/DC Converters
No full textThis paper presents a novel approach of designing saturated Higher-Order Sliding Mode (HOSM) controllers for a class of DC/DC converters. Specifically, the proposed controller aims at guaranteeing boundedness and smoothness of the duty cycle feeding the Pulse-Width-Modulator. The novel control architecture consists of the so-called Bounded Integral Control (BIC) combined with a discontinuous HOSM control algorithm. The main strength of the proposed approach is its general applicability to a large class of DC/DC converters. Numerical results testify the effectiveness of the proposed approach
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