Guy Campion

Dynamic feedback linearization of nonholonomic wheeled mobile robots

Smooth time-varying laws can solve the stabilization problem of nonholonomic mechanical systems. The authors show that by means of dynamic state feedback, it is possible for three-wheeled mobile robots to track arbitrary fast trajectories not reduced to equilibrium points. Dynamical modeling of nonholonomic mechanical systems for the case of three-wheeled mobile robots is considered. Dynamic feedback allows solution of the tracking problem for an omnidirectional mobile robot with less motors than degrees of freedom. This is possible by choosing output functions depending on the mass repartition of the robot.<<ETX>>

Modelling and control of non-holonomic wheeled mobile robots

A general dynamical model is derived for three-wheel mobile robots with nonholonomic constraints by using a Lagrange formulation and differential geometry. It is shown that a static state feedback allows one to reduce the dynamics of the system to a form in which stabilizing input-output linearizing control is possible.<<ETX>>

A slow manifold approach for the control of mobile robots not satisfying the kinematic constraints

Realistic wheeled mobile robots do not satisfy the ideal kinematic constraints because of slipping effects at the wheel/ground contact zones, The slow manifold approach allows us to design feedback control laws taking into account these dynamics and ensuring the tracking error of the closed-loop system to converge toward zero.

Modelling and state feedback control of nonholonomic mechanical systems

The dynamics of nonholonomic mechanical systems is described by the classical Euler-Lagrange equations subjected to a set of nonintegrable constraints. It is shown that nonholonomic systems are strongly accessible whatever the structure of the constraints. They cannot be asymptotically stabilized by a smooth pure state feedback. However, smooth state feedback control laws can be designed which guarantee the global marginal stability of the system with the convergence to zero of an output function whose dimension is the number of degrees of freedom.<<ETX>>

Traffic modeling and state feedback control for metro lines

A complete traffic analysis for sequential metro lines with or without reference to a nominal time schedule is developed. The intrinsic instability of metro lines is pointed out. It is shown how well-chosen state-space formulations allow design of state-feedback control algorithms ensuring the stability of the system. The proposed traffic control algorithms have simple forms and are easy to implement in real-life systems. Simulations show the robustness of the proposed traffic control algorithms against disturbances occurring randomly on a loop line and their efficiency when compared to a classical time margin strategy. >

Stability analysis of a vision-based control design for an autonomous mobile robot

We propose a simple control design allowing a mobile robot equipped with a camera to track a line on the ground. The control algorithm, as well as the image-processing algorithm, are very simple. We discuss the existence and the practical stability of an equilibrium trajectory of the robot when tracking a circular reference line. We then give a complementary analysis for arbitrary reference lines with bounded curvature. Experimental results confirm the theoretical analysis

Identification of the barycentric parameters of robot manipulators from external measurements

An original procedure for the estimation of the barycentric parameters of a robot is presented. This procedure requires only the processing of measurements provided by an external experimental set-up. The procedure is based on the property that the relations between the robot motion and its reactions on the bedplate are completely independent of the internal joints forces. A convincing validation experiment on a PUMA 562 is reported.

A sufficient condition for simultaneous stabilization

The condition under which it is possible to find a single controller that stabilizes k single-input single-output linear time-invariant systems p/sub i/(s) (i=1,. . .,k) is investigated. The concept of avoidance in the complex plane is introduced and used to derive a sufficient condition for k systems to be simultaneously stabilizable. A method for constructing a simultaneous stabilizing controller is also provided and is illustrated by an example. >

Sampled-data Adaptive-control of a Class of Continuous Nonlinear-systems

The problem is addressed of deriving sampled-data control laws for a class of nonlinear continuous systems. The concept of approximate state-feedback linearizing control is defined for sampled-data models arising from the sampling of continuous-time systems. Such control laws are then designed for both non-adaptive and adaptive cases and a detailed performance analysis is performed.

ROLLMOBS, a new drive system for omnimobile robots

Typical mobile robot structures (e.g. wheelchairs or car-like robots) do not have the required mobility for common applications such as displacement in an office, hospital, workshop, etc. New structures based on the “universal wheel” (i.e. a wheel equipped with freely rotating rollers) have been developed to increase mobility. However, these structures have important drawbacks such as spurious vibrations and limited load capacity. This paper presents a new type of omnimobile platform using an original combination of spherical wheel and universal wheel. This structure will improve the robot capabilities, i.e., load capacity and surmountable bumps.