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This paper presents a composite controller for tip position tracking of flexible link manipulators. In this regard, an inner/outer control structure is proposed. Opposed to previous conducted researches in this area, the desired reference trajectory is robustly modified (online) to minimize the tracking error of the tip utilizing the outer controller. The outer trajectory modifier is a μ synthesis...
This paper presents an adaptive robust tracking control method for a mobile manipulator during trajectory tracking. The parameters of the mobile manipulator dynamics are updated online. The design of the controller is based on two cascaded subsystems: a minimum norm kinematic controller with command saturation, and an adaptive controller that compensates the dynamics of the mobile manipulator system...
We have been developing an exoskeleton robot (ExoRob) for assisting daily upper limb movements (i.e., shoulder, elbow and wrist). In this paper we have focused on the development of a 2DOF ExoRob to rehabilitate elbow joint flexion/extension and shoulder joint internal/external rotation, as a step toward the development of a complete (i.e., 3DOF) shoulder motion assisted exoskeleton robot. The proposed...
A lower limbs rehabilitative training robot was designed to improve walking ability of patients who suffer from impairment in locomotion after neurology injuries or aged persons who lack walking capability. The robot was fixed with four omni-directional wheels which can move within any radius in any direction. When the robot is running, some undetected uncertainty disturbances change its running trajectory,...
The problem of controlling load perturbed induction motors is tackled by means of an observer based robust discrete-time control. In this scheme, model uncertainties and external disturbances are included in a general additive disturbance input which is to be on-line estimated and subsequently rejected via the controller actions. The observer carries out the disturbance estimation, thus reducing the...
This paper presents a new formulation for “Equivalent Control” used in sliding mode control. Although in literature there exist a unique equivalent control for a given system and linear sliding surface, it is shown that the equivalent control can be non unique. Further this flexibility in equivalent control is used to obtain the sliding mode control for specific needs such as actuator saturation,...
In this paper, a robust fault-tolerant control strategy for constrained multisensor linear systems, subject to sensor faults and in the presence of bounded state and output disturbances is proposed. The scheme verifies that for each sensors-estimator combination, suitable residual variables lie inside pre-computed sets and selects the more appropriate combination based on a chosen criterion. An active...
This paper addresses the coordination and trajectory tracking control design for a multiple mini rotorcraft system. The dynamic model of the mini rotorcraft is presented using the Newton-Euler formalism. Our approach is based on a leader/follower structure of multiple robot systems. A nonlinear controller based on nested saturations and a multi-agent consensus control are combined to obtain a flight...
This paper describes a behavioral approach to the synthesis of controllers for the execution of tasks by mobile robots. The paradigm integrates two distinct methods for decision making under uncertainty, namely Markov decision processes and differential inclusions. The target application is surveillance systems where mobile robots can approach intruders to take their mugshot or block exit pathways...
In the forest industry, trees are logged and harvested by human-operated hydraulic manipulators. Eventually, these tasks are expected to be automated with optimal performance. However, with todays technology the main problem is implementation. While prototypes may have rich sensing information, real cranes lack certain sensing devices, such as encoders for position sensing. Automating these machines...
In this work we are evaluating the performance and design of a novel wearable haptic interface suitable for the appliance in large workspaces. We are investigating three main questions regarding the performance of the wearable haptic interface. The first question is whether stable and transparent presentation of contact with rigid surfaces on objects can be simulated with the wearable haptic interface...
Model predictive control (MPC) has developed considerably in the last decades both in industry and in academia. This success is due to the fact that MPC is perhaps the most general way of posing the control problem in the time domain. One of the main advantages of MPC is that model uncertainties can be taken explicitly into account and this allows for the consideration of faulty process behavior....
This paper presents the control system of an autonomous vehicle capable of perceiving and describing the environment using different inputs, such as GPS waypoints, roadways borders and lines, leader vehicles, and obstacles to be avoided. The controller has been implemented and tested for the VisLab Intercontinental Autonomous Challenge, a long intercontinental trip that aims to demonstrate capabilities...
The inverted pendulum system has been widely studied to test control techniques of nonlinear systems. We introduce a new alternative to control systems with complex dynamics, based on evolutionary game theory. Specifically, we use dynamics that are represented by the replicator equation, which has been successfully used in autonomous systems, control flight, and temperature control. Simulation results...
In this paper an observer for a polynomial nonlinear (nonautonomous) system constrained to a bounded subset of the state space is considered. The presented approach allows the construction of a locally asymptotically stable observer, which is guaranteed to be stable for any possible state within the limits. It is based on a theorem of Jacobi and Prestel. The problem is rewritten as an optimization...
This paper proposes a new method for designing a weigh feeder control system. The model of a weigh feeder cannot be obtained accurately because its dynamic characteristics are time varying and its high frequency vibration modes are not easily identified. In this paper, a weigh feeder is assumed to be a first-order plus integrator system, and a control law consists of a constant feed-forward control...
This paper addresses the problem of idle speed control of hydrogen fueled internal combustion engine (H2ICE) using model predictive control (MPC) and sampled data control (SDC) theories. In the first step, results from SDC theory and a version of MPC are collectively employed to obtain a rigorously developed new generic control strategy. Here, a controller, based on a family of approximate discrete...
This paper considers the finite-time controller design for wheeled mobile robots. After the mobile robot dynamics have been transformed into an advantageous form, called the heisenberg form, a finite-time controller is designed in order to promulgate the practical stability of the system. The desired stability property of the closed-loop system is provided by applying a homogeneous sliding mode controller,...
This paper considers the problem of controlling both the planar position and the orientation of an underactuated airship with a reduced number of actuators in the presence of a unknown persistent wind disturbance. The airship is a nonholonomic system described by a set of nonlinear equations and the dynamics are subjected to bounded uncertainties. A smooth and time-varying coordinate transformation...
Because horizontal boom motion of a rotary crane generates two-dimensional load-sway, skilled labor is required to control the rotary crane, and automatic control system that achieves boom positioning and load-sway suppression simultaneously has been widely studied thus far. Although vertical and horizontal boom motion is employed for the load-sway suppression in most existing studies, it seems undesirable...
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