Search results for "Computer Science::Robotics"
showing 10 items of 90 documents
Adaptive Finite-Time Control for a Flexible Hypersonic Vehicle with Actuator Fault
2013
The problem of robust fault-tolerant tracking control is investigated. Simulation on the longitudinal model of a flexible air-breathing hypersonic vehicle (FAHV) with actuator faults and uncertainties is conducted. In order to guarantee that the velocity and altitude track their desired commands in finite time with the partial loss of actuator effectiveness, an adaptive fault-tolerant control strategy is presented based on practical finite-time sliding mode method. The adaptive update laws are used to estimate the upper bound of uncertainties and the minimum value of actuator efficiency factor. Finally, simulation results show that the proposed control strategy is effective in rejecting unc…
General aspects regarding the kinematic and dynamic analysis of the fabric take up/cloth roller
2017
The aim of this paper is to presents different aspects regarding the kinematic and dynamic behaviour of the fabric winding at the weaving loom. In this paper shall be presented the kinematic diagram for operating the cloth roll on the weaving machine, making the study of kinematic and dynamic cloth behaviour, setting up the expression of fabric tension. Finally, where drawn the charts of the variation of the fabric load depending by kinematic and constructive parameters.
Multi-Objective Design of Optimisation of a Class of PKMs - The 3-DOF Gantry-Tau
2010
The main contribution of this paper is the use of the evolutionary multi-objective methodology based on the com plex search algorithm and geometric approaches to optimise a parallel kinematic structure. The design optimisation scheme includes the kinematic (collisions free workspace), elastostatic (Cartesian stiffness in the Y direction) and elastodynamic (first resonance frequency) properties of the PKM as the objectives. The optimisation constraints are the support frame lengths, actuator positions, end-effector’s kinematic parameters and the robot’s arm lengths. The optimisation results are presented in this paper.
Optimization model predictions for postural coordination modes
2003
International audience; This paper examines the ability of the dynamic optimization model to predict changes between in-phase and anti-phase postural modes of coordination and to evaluate influence of two particular environmental and intentional constraints on postural strategy. The task studied was based on an experimental paradigm that consisted in tracking a target motion with the head. An original optimal procedure was developed for cyclic problems to calculate hip and ankle angular trajectories during postural sway with a minimum torque change criterion. Optimization results give a good description of the sudden bifurcation phase between in-phase and anti-phase postural coordination mo…
Trajectory tracking of underactuated underwater vehicles
2003
This paper deals with a control strategies for underactuated underwater vehicles whose target is the tracking of a space trajectory. A cascade control strategy is employed which brings to a control law consisting of: 1) a kinematic control law, derived from the vehicle kinematic model, which forces this model to track the reference trajectory; and 2) a dynamic control law which forces the system to track the reference signals given by the kinematic control law. Conditions for asymptotic tracking of the trajectory are given with reference to the standard dynamical model of the above vehicle. An observer of the marine current is also added in order to process the control law. Simulation tests…
Off-line path correction of robotic face milling using static tool force and robot stiffness
2015
In this paper the developed method for off-line compensation of tool deflections when milling aluminum with an industrial robot is presented. The efficiency of this approach is verified with high precision measurements of deflections using a laser tracker. The compensation method includes both the static milling process model which can predict the mean value components of the tool forces and a new combined local/global approach for estimating the combined stiffnesses of joints. With a process model such as the one presented in this paper and estimates of the robot's joint stiffness values, the tool path can be adjusted to counteract deflections of the tool during milling operations. The mod…
Robust Control Allocation for Spacecraft Attitude Stabilization under Actuator Faults and Uncertainty
2014
A robust control allocation scheme is developed for rigid spacecraft attitude stabilization in the presence of actuator partial loss fault, actuator failure, and actuator misalignment. First, a neural network fault detection scheme is proposed, Second, an adaptive attitude tracking strategy is employed which can realize fault tolerance control under the actuator partial loss and actuator failure withinλmin=0.5. The attitude tracking and faults detection are always here during the procedure. Once the fault occurred which could not guaranteed the attitude stable for 30 s, the robust control allocation strategy is generated automatically. The robust control allocation compensates the control …
A new approach to the design of a speed-torque-controlled rubber V-belt variator
2005
This paper presents a new model for a torque-speed-sensing rubber V-belt variator. The actuators are of the centrifugal roller kind on the driver side and a helical torque cam plus a compression-torsion spring on the driven side. The equations permit designing the actuator geometry in order to keep the transmissible torque as close as possible to the torque request in the whole operative field. Moreover, a procedure is suggested for the most proper design of an automatic variator of this kind. It permits choosing the required variogram of the transmission, i.e. the matching between the engine and the transmission, and designing the actuators: roller mass, housing shape, contact plate angle…
Stability and Noises Evaluation of Fuzzy Kalman UAV Navigation System.
2009
In this paper a new Fuzzy/Kalman navigation system for Unmanned Aerial Vehicles (UAV) is presented. A closed loop velocity Fuzzy navigation system is proposed for stabilizing the UAV in a reference trajectory generated dynamically and for obtaining a forward velocity command. The Kalman's filter (KF) is included in the feedback line of the fuzzy control system to filter the internal noise of the sensors and to evaluate the external noise due to possible perturbations of the nominal motion. The efficiency of the navigation system has been shown through experimental tests in a Matlab environment.
Synergic algorithms for the planning and the intelligent following of a trajectory for non-holonomic vehicles
2008
Although there are many studies about two wheels non-holonomic vehicles, in order to simplify the problem the planning and the following of trajectories or paths are generally considered two different phases. In this paper, two algorithms for the synergic working of trajectory planning with intelligent trajectory following are presented. The "trajectory shape" characteristics obtained in the planning phase are used for the efficient trajectory following. From the shape, in order to follow the trajectory, an intelligent controller calculates, without further elaboration, the reference wheels velocity of the vehicle. The knowledge of trajectory shape characteristics and curvature constraints …