In this article, we present the kinematic calibration of H4 parallel robot using vision-based measuring device. Calibration is performed according to the inverse kinematic model method, using first the design model then a model developed for calibration purpose. With a precision of the order of magnitude of 0.2 mm and 0.03/spl deg/, our vision system allowed us to obtain a final positioning accuracy of the end-effector lower than 0.5 mm. Conclusions are given for the calibration of this class of mechanisms.

This paper deals with the experimental identification of the dynamic parameters of parallel machines. The dynamic parameters are estimated by using the weighted least squares solution of an over determined linear system obtained from the sampling of the dynamic model along a closed loop exciting trajectory. Experimental results are exhibited for the H4 robot, a fully parallel structure providing 3 degrees of freedom (DOF) in translation and 1 DOF in rotation. A comparative study is performed depending on the available measurements, i.e., different sensor locations (motor, end effector).

The forward kinematic model (FKM) of a redundantly actuated robot is not unique: if each actuator is equipped with an encoder, there are more joint data than strictly necessary for computing nacelle position. It is then possible to fuse competitive data to find the nacelle position. This paper proposes then a method based on a probabilistic approach to determine how computing the FKM to obtain, in terms of probability, the lowest Cartesian error.

This paper presents a new family of fully-parallel robots producing motions of the Schoenflies displacements subgroup (three translations and one rotation about a given axis in world coordinates) for high-speed handling and machining. First, the structure's ability to provide this four-degrees-of-freedom motion is presented. Then, two of its possible designs are analyzed: the symmetrical and the asymmetrical one. Constructive designs are then presented. Some of the prototype's preliminary control results are given to prove the H4 robot's efficiency.

Twice (tilling device with wide capacity), a new amplification device able to double the tilting angle of a parallel mechanism, is presented. A singularity analysis is carried out: it proves that Twice can give a huge tilting angle to parallel kinematic machines. Finally, practical implementation features are discussed.

This paper introduces a control strategy based on redundant sensors that leads to parallel robots accuracy enhancement. The method is presented in general, then applied to a 4-DOF parallel robot. Practical implementation issues, simulation results and experimental validation are addressed.

This paper first recalls the concept of H4 parallel mechanism, and the kinematic models necessary for real-time control are derived. A simple and efficient control system based on a combination of Windows NT and RTX is used to demonstrate its performances. Results prove the efficiency of H4 serving as a high-speed pick-and-place robot.

Presents a 3-DOF redundant parallel mechanism, ARCHI, designed as a sub-part of a 5-axis hybrid machine. The redundant parallel mechanism design and its models are recalled; different ways for its control and first motion results are presented, proving the ability of ARCHI to offer an unlimited rotation capability.