The paper is an introduction and overview to the problem of feedback control of nonholonomic wheeled vehicles. Solutions proposed during the last decade and a new approach currently developed by the authors of this article are presented.

In this paper a trajectory tracking control problem for a nonholonomic mobile robot by making use of a kinematic oscillator has been solved. Firstly - time varying oscillator is examined to control nonholonomic mobile robot based only on its kinematics. Secondly - backstepping procedure is proposed to include robot dynamics and servo loop. It is shown that overall multilevel controller is asymptotically globally stable to a small error different from zero. A wide range of simulation results are presented which illustrate behaviour of the controller with respect to tuning its parameters. Some preliminary experiments are reported too.

The problem of the real time estimation of the position and orientation of moving objects for position-based visual servoing control of robotic systems is considered in this paper. A computationally efficient algorithm is proposed based on Kalman filtering of the visual measurements of the position of suitable feature points selected on the target objects. The efficiency of the algorithm is improved by adopting a pre-selection technique of the feature points, based on Binary Space Partitioning (BSP) tree geometric models of the target objects, which takes advantage of the Kalman filter prediction capability. Computer simulations are presented to test the performance of the estimation algorithm in the presence of noise, different types of lens geometric distortion, quantization and calibration errors.

A novel strategy for rehabilitation of locomotion impaired subjects uses a Body Weight Support Technique (BWST) on a treadmill which involves three to four therapists to carry out the required patient training exercises on the treadmill. This paper briefly describes (i) the essence of the novel rehabilitation strategy, including its medical background, (ii) the technical approach to the design and development of a robotic device aimed to reduce the manual involvement of at least two therapists in the locomotion training exercises on a treadmill, and (iii) the main conceptual design features of a possible robotic device.

This paper describes the structure of sensor system for a~mobile robot. The information flow in this sensor system is also presented, including a~short description of used buses and protocols. Components used for construction of the system are briefly characterized. In one of the sections of the paper, an obstacles detection algorithm, useful for path planning for mobile robots, is presented. The application of this algorithm has been enclosed in that section, summarized by experimental results. Good speed of image processing, obtained by proposed method, gives possibility to detect obstacles in real time.

We propose a design method of the feed-forward torques and the reference trajectory for an arm with flexible joints and unknown stiffness coefficients. The bounds on the control torque are included explicitly. The designed commanded feed-forward torques and the corresponding reference trajectory are close to be time-optimal. The control law for each drive torque is composed with the commanded feed-forward torque and linear angular position and velocity feedback. The torques and the trajectory are used as input signals of PD-controllers.
In a case of one-link flexible arm it is proved that so-called 'fluent' control torque enables to reach the desired motion with a small error and without large vibrations in the flexible joint. Designed fluent commanded feed-forward torque is successfully implemented in numerical experiments. The stiffness coefficient is assumed to be unknown so the mathematical model of the flexible arm is not known exactly.
In two-link flexible arm the stiffness coefficients are also assumed unknown. Due to discontinuities of the optimal control functions and not acceptable jumps in the optimal control torques a `trapezoidal' fluent control technique is proposed. Numerical experiments show that the designed control is close to time-optimal.
The approach presented in the paper can be extended to systems with more links and can take the gravity into consideration. However, in this case a time-optimal or a quasi-time-optimal control for the associated rigid system have to be designed.

Differential linear repetitive processes are a distinct class of 2D linear systems which pose problems which cannot (except in a few very restrictive special cases) be solved by application of existing linear systems theory, and hence by the use of many of the currently available tools for computer aided analysis and simulation. One such problem area is the construction of accurate numerically well conditioned discrete approximations of the dynamics of differential processes which could, as one example of a number of immediate applications areas, form the basis for the digital implementation of control laws. In this paper, we undertake a detailed investigation of the critical problems which arise when attempting to construct useful (for onward asnalysis/design studies) discrete approximations of the dynamics of differential linear repetitive processes and develop solutions to them. Numerical examples to support the results obtained are also given using a specially developed MATLAB based toolbox.