This paper addresses the problem of global output feedback, link position tracking control of robot manipulators. Specifically, a robust, Lyapunov-based controller is designed to ensure that the link position tracking error is globally uniformly ultimately bounded despite the fact that only link position measurements are available in the presence of incomplete model information (i.e., parametric uncertainty and additive bounded disturbances).

This paper proposes a novel path planning algorithm of 3-D articulated robots with moving bases based on a generalized potential field model. The approach computes, similar to that done in electrostatics, repulsive forces and torques between charged objects. A collision-free path can be obtained by locally adjusting the robot configuration to search for minimum potential configurations using these forces and torques. The proposed approach is efficient since these potential gradients are analytically tractable. In order to speedup the computation, a sequential planning strategy is adopted. Simulation results show that the proposed algorithm works well, in terms of collision avoidance and computation efficiency.

Autonomous navigation of an indoor mobile robot, using the global ultrasonic system, is presented in this paper. Since the trajectory error of the dead-reckoning navigation increases significantly with time and distance, the autonomous navigation system of a mobile robot requires self-localization capa-bility in order to compensate for trajectory error. The global ultrasonic system, consisting of four ultrasonic generators fixed at a priori known positions in the work space and two receivers mounted on the mobile robot, has a similar structure to the well-known satellite GPS(Global Positioning System), which is used for the localization of ground vehicles. The EKF (Extended Kalman Filter) algorithm is utilized for self-localization and autonomous navigation, based on the self-localization algorithm is verified by experiments performed in this study. Since the self-localization algorithm is efficient and fast, it is appropriate for an embedded controller of a mobile robot.

In this paper we present a globally convergent and ultimately exponentially convergent tracking controller for an X4 Flyer rotor craft. The desired or reference trajectory is restricted in one way: its scalar thrust must be uni signed and bounded away from zero. The proposed controller is a two phase one. Phase I converges the attitude (orientation) error and thrust error to zero globally and ultimately exponentially. Phase II is a position tracking and relative yaw angle tracking controller, which is not globally convergent by itself. By carefully postponing a switch from Phase I to Phase II, we are able to assure that Phase II will ultimately drive the position error and relative yaw angle error to zero exponentially. In problem-statement/theorem/proof format, we define the system, the control objective, the proposed controller, and a rigorous proof that the controller maintains boundedness of all closed loop signals and provides global convergence of the tracking error to zero and also ultimately exponential convergence of the tracking error to zero.

The 3-PS structure features one rigid body (platform) connected to another rigid body (base) by means of three kinematic chains (limbs) of type PS (P and S stand for prismatic pair and spherical pair, respectively). All the 3-degree-of-freedom parallel manipulators with three connectivity-5 limbs, each one constituted of one passive (i.e. not actuated) prismatic pair, one passive spherical pair and one actuated kinematic pair of any type, become 3-PS structures when the actuated pairs are locked. Direct kinematics of this class of manipulators is tied to the properties of the 3-PS structure. In particular, the direct position analysis is tied to the assembly modes of the 3-PS structure; whereas the determination of the singularities of the direct instantaneous problem is tied to the determination of the singular geometries of the 3-PS structure, where instantaneous relative motions between platform and base are possible. The solution of these two problems is necessary both for designing the manipulators and for controlling them during motion. This paper deal with the determination of the singular geometries of the 3-PS structure.

This paper presents an adaptive impedance control scheme for an $n$-link constrained rigid robot manipulator without using the regressor. In addition, inversion of the estimated inertia matrix is also avoided and the new design is free from end-point acceleration measurements. The dynamics of the robot manipulator is assumed that all of the matrices in robot model are unavailable. Since these matrices are time-varying and their variation bounds are not given, traditional adaptive or robust designs do not apply. The function approximation technique is used here to represent uncertainties in some finite linear combinations of the orthogonal basis. The dynamics of the output tracking can thus be proved to be a stable first order filter driven by function approximation errors. Using the Lyapunov stability theory, a set of update laws is derived to give closed loop stability with proper tracking performance. A 2 DOF planar robot with environment constraint is used in the computer simulations to test the efficacy of the proposed scheme.

A biped walking robot, named EP-WAR3 (Electro-Pneumatic-Walking-Robot), has been designed, built and tested at LARM (Laboratory of Robotics and Mechatronics) in Cassino. EP-WAR3 is provided with a suitable binary pneumatic actuation in order to be controlled through a common PLC (Programmable-Logic-Controller) as an event-based system in an on/off environment. The walking stability of the biped robot is obtained by using suction-cups, which are installed on the underside of each foot. EP-WAR3 is able to walk along a straight line with two different step sizes, turn right and left, and to climb and to descend stairs. A suitable motion analysis and programming technique of the PLC controller is proposed in order to obtain suitable walking capabilities and flexibility of the robot.

Fault diagnosis plays an important role in the operation of modern robotic systems. A number of researchers have proposed fault diagnosis architectures for robotic manipulators using the model-based analytical redundancy approach. One of the key issues in the design of such fault diagnosis schemes is the effect of modeling uncertainties on their performance. This paper investigates the problem of fault diagnosis in rigid-link robotic manipulators with modeling uncertainties. A learning architecture with sigmoidal neural networks is used to monitor the robotic system for off-nominal behavior due to faults. The robustness, sensitivity, missed detection and stability properties of the fault diagnosis scheme are rigorously established. Simulation examples are presented to illustrate the ability of the neural network based robust fault diagnosis scheme to detect and accommodate faults in a two-link robotic manipulator.

The questions when and why one needs to use mathematical models, and especially the models of dynamics, represent still an unresolved issue. A general answer would be that dynamic modelling is needed as a tool when designing structure of the system and its control unit. In this case we talk about simulation. The other application is in on-line control of the system – the so-called dynamic control. While in simulation one generally uses the best available model, the control can be based on a reduced dynamics, depending on a particular task. The aim of this paper was to highlight the problems important for the dynamics of humanoids and their dynamic environment.

This article is proposing a grasp recognition and grasp mapping method for a land mine clearance master-slave system. The system consists of a data glove and a powerful hydraulic hand. Because of the different structure of the master and slave hand a mapping from master grasp to slave grasp has to be implemented. The paper presents a grasp recognition method by Neural Network (NN) and a mapping method. The introduced mapping method allows the operator more intuitive grasping.

The manipulability index suggested by Yoshikava is an important tool for the design of mechanisms and their control. It represents a quantitative measure of the functionality and the ability for realizing some tasks or groups of tasks. This index is some kind of performance measure and should be taken into consideration in the design phase of a mechanism and also in the design of control algorithms.

In this paper two important properties of the manipulability index are investigated. The first part of the present work demonstrates that manipulability of a mechanism is independent of task space coordinates. In the second part, a proof of the independency of the manipulability index on the first DOF is given.

This invariance is important for simplification of the mechanism's Jacobian matrix and gives excellent insight into the dependences of configuration space coordinates on this index. Moreover, it proves that the manipulability index is determined only by relative positions of the mechanism itself and by the mechanism's geometry.

Finally, the properties of the manipulability index are illustrated by some examples for fundamental open kinematical chain structures.

In our previous work, we developed a compact 6-DOF haptic interface as a master device which achieved an effective manual teleoperation. The haptic interface contains a modified Delta parallel-link positioning mechanism. Parallel mechanisms are usually characterized by a high stiffness, which, however, is reduced by elastic deformations of both parts and bearings. Therefore, to design such a parallel mechanism, we should analyze its structural stiffness, including elastic deformations of both parts and bearings. Then we propose a simple method to analyze structural stiffness in a parallel mechanism using bearings. Our method is based on standard concepts such as static elastic deformations. However, the important aspect of our method is the manner in which we combine these concepts and how we obtain the value of the elasticity coefficient of a rotation axis in a bearing. Finally, we design a modified Delta mechanism, with a well-balanced stiffness, based on our method of stiffness analysis.