This paper proposes a new control algorithm for a linear belt-driven servomechanism. The elasticity of the belt and large nonlinear friction along with large variation of parameters limit the applicability of the belt driven servosystems. Design of simple control that can guarantee stable, vibration-free operation for large variation of load is needed to extend application of such a linear stage. The proposed control is based on the application of sliding mode methods combined with Lyapunov design so it guarantees the stability of the system. Due to the restriction of the system motion to specially selected sliding mode manifold the vibration free position tracking is achieved with very good disturbance rejection. Proposed algorithm is simple and practical for an implementation and the tuning procedure of the control parameters is simple. The experiments have shown that the proposed control scheme effectively suppresses vibrations and assures wide closed-loop bandwidth for position tracking control.

A "sliding mode observer" based approach to estimate rigid and affine motion of an object is presented in this paper. Two different problems are considered. First the motion is of rigid type and constrained to a plane, and object, e.g. a mobile robot, is viewed using a stationary camera at a fixed certain distance in the normal direction of the motion plane, thus the motion in image plane also being rigid. Then we consider the problem of identifying parameters of an affine motion which may result as the scaled orthographic projection of an almost planar object undergoing 3D rigid motion. In either case, certain number of feature points extracted from the images of the object is used for parameter estimation. Though we know these feature points in every frame, we also construct their estimates, and try to make these estimates follow the actual ones using sliding mode control. It turns out that the control employed in this framework allows us to estimate the motion parameters of the moving object in an elegant way.

This paper presents a novel method for controlling force and position simultaneously using a sliding-mode position controller and a sliding-mode position error estimator for the position controller according to force error (which is used to control force essentially). The main advantage of this method is that there is no explicit control mode switching between distinct force and position controllers, but one sliding-mode position controller, for which the force error affects the position error by means of a sliding-mode position error estimator, is used for both cases. With experimental results on a voltage-driven piezo actuator, submicron accuracy (a maximum position error of 0.2 μm) for position control and a maximum force error of 0.02 N are achieved. Also, it is shown that with this approach, the jump of control input (the main stability problem of using separate force and position controllers) is removed without losing control power.

In this work, we suggested a solution for the basic tasks of a mobile robot capable of being a building block of an intelligent agent in group. This solution includes obstacle avoidance and goal tracking implemented as two different controllers. A geometry based behavior arbitration is proposed for fusing the output of those two controllers. Proposed structure is tested both on simulations and on real robot with different scenarios. Results have confirmed the high performance of the method.

In this paper a discrete-time Sliding-Mode (SM) based controller design method is presented. The controller is designed for a general SISO system with nonlinearity and external disturbance. Closed-Loop behavior of the general system with the proposed control and Lyapunov stability is shown. It will be shown that application of the proposed controller forces the state trajectory to be within an O(Ts 2 ). The proposed controller is applied to a stage driven by a piezo drive that is known to suffer from hysteresis nonlinearity. Structure of proposed SMC controller is proven to offer chattering-free motion and rejection of the disturbances represented by hysteresis and the time variation of the piezo drive parameters. As a separate idea to enhance the accuracy of the closed loop system a combination of disturbance rejection method and the SMC controller is explored. The disturbance observer is constructed using a second order lumped parameter model of the Piezo-Stage and is based on SMC framework. Closed-loop experiments are presented using PID controller with disturbance compensation and Sliding-Mode Controller with and without disturbance compensation for the purpose of comparison.

Abstract Torque and speed sensorless induction motor control is presented in this paper. The idea is realized using a sliding mode closed loop rotor flux observer for estimation of electromotive force of machine. This signal is then used in nonlinear stator flux and torque control of induction motor and in rotor flux observer for speed and flux estimation. The analysis of the proposed method is included. Proposed control scheme was implemented on DSP system extended with FPGA where PWM procedure with dead time compensation was realized. Experimental results demonstrated high efficiency of the proposed estimation and control method.

In this work, we are presenting a sliding mode controller approach for bilateral control. The controller consists of sliding mode force and hybrid (force/position) controllers for master and slave sides, respectively. Main issues such as transparency and time delay have been addressed in the derivation and the implementation of the controller. The approach takes the overall system (unified master and slave sides) as one system and therefore uses the transparency aims of the other approaches as the means for the derivation of the controller. It also makes use of a "reflex mechanism" to protect the slave side and its environment in case of large time delays, which disables the operator to react in time. The effectiveness of the proposed control scheme is evaluated experimentally and a maximum position error of one step increment of the encoder and a maximum torque error of 3/spl times/10/sup -6/ Nm are achieved.

In this paper a control of method for a piezoelectric stack actuator control is proposed. In addition briefly the usage of the same methods for estimation of external force acting to the actuator in contact with environment is discussed. The method uses sliding mode framework to design both the observer and the controller based on an electromechanical lumped model of the piezoelectric actuator. Furthermore, using a nonlinear differential equation the internal hysteresis disturbance is removed from the total disturbance in an attempt to estimate the external force acting on the actuator. It is then possible to use this external force estimate as a means of force control of the actuator. Simulation and experiments are compared for validating the disturbance and external force estimation technique. Some experiments that incorporate disturbance compensation in a closed-loop SMC control algorithm are also presented to prove the effectiveness of this method in producing high precision motion.

The development of control method for an autonomous mobile robot that can be part of a multiagent system is the subject of this thesis. Mobile robots are built different purposes; for that reason, physical size, shape and mechanics, such as driving mechanism, of the robots would be very different. They are most of the time required to realize more than one goal at a time. Hence, as a minimum, required control must work in real-time and be able to respond to sudden changes that may occur in the environment. There is extensive research carried out, about autonomous mobile and stationaru robots, ranging from path planning and obstacle avoidance to multiple autonomous mobile robots. Proposed approach, for mobile robot control, is a layered structure and supports multi sensor perception. Each control layer uses only necessary sensor functions for its own process. Moreover, layers of control do not evaluate the signals to the necessary form asked by the layers. In this work, potential field method is implemented for obstacle avoidance. Unlike other solutions in the same framework, in this work assumed repulsive forces of the obstacles and attractive force of the goal point are treated separately. Then obstacles avoidance and goal tracking are fused in such a way that major drawbacks of the potential field method are overcome. Proposed control is tested on simulations where different scenarios are studied. The simulation results confirmed the high performance of the method. The proposed control is a potential alternative for mobile robots control operating in dynamic environments and as an agent in a multiagent system

In this paper the robust motion control systems in the sliding mode framework are discussed. Due to the fact that a motion control system with n d.o.f may be mathematically formulated in a unique way as a system composed of n second order systems, design of such a system may be formulated in a unique way as a requirement that the generalized coordinates must satisfy certain algebraic constraint. Such a formulation leads naturally to sliding mode framework to be applied. In this approach constraint manifolds are selected to coincide with desired constraints on the generalized coordinates. It has been shown that the CMC can be interpreted as a realization of the acceleration controller thus possessing all robust properties of the acceleration controller framework. The possibility to treat both unconstrained motion (the motion without contact with environment) and constrained motion in the same way is shown.

In this paper a method for piezoelectric stack actuator control is proposed. In addition a brief discussion about the usage of the same methods for estimation of external force acting to the actuator in contact with environment is made. The method uses sliding mode framework to design both the observer and the controller based on an electromechanical lumped model of the piezoelectric actuator. Furthermore, using a nonlinear differential equation the internal hysteresis disturbance is removed from the total disturbance in an attempt to estimate the external force acting on the actuator. It is then possible to use this external force estimate as a means of force control of the actuator. Simulation and experiments are compared for validating the disturbance and external force estimation technique. Some experiments that incorporate disturbance compensation in a closed-loop SMC control algorithm are also presented to prove the effectiveness of this method in producing high precision motion.

In this paper, the previously proposed neuro-sliding mode controller for SISO systems by the authors is modified for MIMO case. The structure benefits from the power of sliding mode control and nonlinear function approximation ability of the neural networks. The controller is a two layer feed-forward neural network and weight updates are done using backpropagation algorithm. The error function that is introduced to the neural network is such that the states of the system are restricted to belong to a certain manifold in state space. Different from the works done until now, in this work the aim is not calculating the equivalent control but instead finding the control input by just minimizing a certain error function. Simulation results demonstrate the performance of the controller.