Mateusz Cholewinski

Towards Practical Implementation of an Artificial Force Method for Control of the Mobile Platform Rex

The article describes skid steering mobile platform, which is a nonholonomic robot. For controlling such a robot artificial force method has been used. This method assumes that the number of control inputs is the same as the number of controlled variables. Simultaneously additional control signal is equal to zero equivalently. Considerable attention is paid to possibility of practical application of the described algorithm in the physical equipment.

Virtual Force Concept in Steering Mobile Manipulators with Skid-Steering Platform Moving in Unknown Environment

Underactuated control system, namely mobile manipulator mounted on skid-steering platform has been considered in the paper. As a control scheme the concept of virtual force is presented and discussed. In such concept, full rank of input matrix, describing relationship between controlled variables and number of actuators, has been assumed. The signal of the assumed additional actuator is equal to zero equivalently (because this force is “virtual” and it does not exist in practice) but in this way the invertibility of input matrix can be achieved. The equation of the implicit function generates the reference signals needed in control algorithm. Mathematical proof of proper action of such control law has been presented using Lyapunov-like function. Efficiency and robustness of control scheme on parametric uncertainty of terrain, which the mobile manipulator is moving on, have been tested in numerous simulations.

Robust Control of Differentially Driven Mobile Platforms

Wheeled mobile platforms constitute an important group of robotic objects. They can be treated as independent robots or as a transportation part of a composite robotic assembly, for instance mobile manipulators. Depending on the kind of the wheels and the way in which they are fixed to the cart, motion of wheeled mobile platforms can be realized with or without slippage phenomenon. If no slippage effect between the wheels and the surface occurs, then there exists some equation describing forbidden directions of realized velocities of the system. Such a relationship is called the nonholonomic constraint in the platform’s motion.

Control of mobile robot for remote medical examination: Design concepts and users' feedback from experimental studies

In this article we discuss movement control of a ReMeDi medical mobile robot from the user perspective. The control is essentially limited to the level of operator actions where the operator is a member of a nursing staff. Two working modes are the base of considerations: long distance (LD) and short distance (SD) movement. In this context two robot control techniques are the subject of study: manual with use of a gamepad and “point and click” on a map that is related to autonomous motion with use of an onboard navigation system. In the SD mode the user manually operates the robot, that is close to a laying down patient on a settee. In the LD mode the mobile base moves autonomously in a space shared with people to the desired position. Two user studies were conducted. The results show that from the perspective of LD mode the autonomous navigation is efficient and reduces the burden of the medical personnel. In the SD case, the results show that the users were able to precisely position the robot. Besides, the users perceived the manual control with the gamepad as intuitive. In all cases the medical personnel consider this technology as safe and useful. Safety is also confirmed by patients.

Software platform for practical verification of control algorithms developed for rescue and exploration mobile platform

This paper presents the architecture of system that has been developed for practical verification of the real-time control algorithms performance intended for servicing mobile platform. The system has been implemented using the hardware-software framework developed within RobREx project. This framework is a composition of a well integrated software tools and hardware devices dedicated for developing a complex, distributed real-time control systems. The framework supports a component-driven development paradigm, provides a ready-made application building blocks and introduces standard interfaces. The elaborated system is composed of several software components that together with hardware devices constitutes the fully functional, experimental testbed that allows testing of control algorithms in real-time.

Deployment of model based robotic control algorithms, designed using Matlab/Simulink, in the form of OROCOS components operating under Linux Xenomai

The article focuses on deployment of model based control algorithms which have passed the stage of simulation analysis in Simulink. The target software platform is OROCOS framework within Linux Xenomai - a real-time operational system. First, the algorithm of transforming of an automatically generated code from Simulink scheme into an OROCOS component is presented. Next, the proposed procedure is discussed and evaluated from the perspective of the control engineers needs.

Influence of mathematical model selection on control signals for mobile manipulator with skid-steering mobile platform

In the paper the skid-steering mobile platform has been considered. Such object should be treated as an underactuated system. Artificial force method has been used as a solution for controlling an underactuated system on the dynamic level. The paper presents the influence of different methods of modeling, based on artificial force method, on the systems behavior, especially on control signals.

Experimental verification of transversal functions for trident snake robot

In the paper control problem of trident snake robot using transversal functions approach has been considered. First, control law based on concept of transversal periodic functions has been introduced. Next, some experiment has been conducted. For experimental part special testbed, including: robotic device - trident snake robot, control system and camera, has been prepared. Experiment has confirmed limited practical application of control based on transversal functions.

Implementation and evaluation of a bilateral teleoperation with use of wave variables in the ReMeDi system for remote medical examination

The article presents a bilateral teleoperation architecture with wave variables that has been applied in a new robotic system for remote medical examination. First we discuss specificity of requirements of the ReMeDi medical system with respect to teleoperation architecture and the process of its selection. Then we discuss implementation issues concerning the architecture. Finally we present evaluation results.

New Approach to the Artificial Force Concept for Skid-steering Mobile Platform

In the paper control algorithm for skid-steering mobile platform is presented. For mathematical model of such an object, expressed in auxiliary coordinates, control law based on the idea of artificial force is introduced. A skid-steering mobile platform is an underactuated control system with a rectangular input matrix. In the approach explored in the paper it was assumed that there exists an additional control input, giving an additional column in input matrix and causing this matrix invertible. Because such an actuator does not exist in reality, this input was kept equal to zero equivalently. Simulations have proved proper work of this method.