Marco A. Arteaga-Pérez

GPI based velocity/force observer design for robot manipulators

In many applications involving a robot in contact with a surface it is important to control the interaction between the manipulator and its environment, usually by employing force sensors. However, sometimes it is desirable to remove them due to a variety of reasons, e.g. high costs, noisy measurements and a narrow bandwidth. To overcome these drawbacks, in this work it is proposed as a velocity/force observer based on the Generalized Proportional Integral (GPI) technique. Joint velocities and contact forces are estimated with only position measurements and then used in a force/position control scheme. Ultimate boundedness of the observation errors is formally proven and an arbitrarily small ultimate bound is then achieved. Simulation results are used to validate the proposed approach.

Adaptive position/force control for robot manipulators in contact with a rigid surface with uncertain parameters

Most position/force control schemes assume that the contact surface is exactly known. In the presence of constraint uncertainties these controllers cannot ensure convergence to zero of position and force errors. In this work, an adaptive scheme is proposed for robot manipulators that perform interaction tasks with a rigid surface. The proposed algorithm takes into account uncertainties in robot and surface parameters. Also, it locally estimates the surface by means of force measurements. Experimental results are presented to illustrate the good performance of our approach.

Robot force control without dynamic model: theory and experiments

Among the many challenges to deal with, when a robot is interacting with its environment, friction at the contact surface and/or at the joints is one of the most important to be considered. In this paper we propose a control algorithm for the tracking of position and force (unconstrained orientation case only) of a manipulator end-effector that does not require the robot model for implementation. This characteristic has the advantage of making it capable to compensate friction effects without any previous estimation. Furthermore, no velocity measurements are needed, and the unit quaternion is employed for orientation control. Experimental and simulation results are provided.

On the GPI approach with unknown inertia matrix in robot manipulators

This article discusses the design of generalised proportional integral observers for the tracking control of robot manipulators. The unknown, possibly state-dependent, additive nonlinearity influencing the input–output description, in terms of the tracking error dynamics is modelled for observer construction purposes, as an absolutely bounded, additive, unknown time-varying perturbation input signal. A disadvantage of the approach lies in the fact that the system inertia matrix is usually required for implementation. In this work, it is shown how the approach can be modified to avoid the use of the inertia matrix when it is unknown. A set of experiments with three different test beds is carried out to show the good performance of the proposed algorithm.

On the Observability and the Observer Design of Differential Pneumatic Pistons

In this paper, an observability analysis for differential pneumatic pistons is presented, together with the design and implementation of linear observers of the Luenberger type. To avoid as much as possible the knowledge of the system model parameters, the generalized proportional integral (GPI) approach is employed for the estimation of unmeasured variables. Experimental results show the good performance of the proposed scheme.

Master/Slave Robotic System for Teaching Motion-Force Manufacturing Tasks

This paper proposes a bilateral master-slave training systems which allows to directly transfer motion and force skills from the human operator to a real slave manipulator trough a master robot. For this, real and virtual surfaces are modeled by geometric constraints, which represent the surface where the task is to be performed. Thus, joint orthogonal decomposition into force and motion is considered. The holonomic constraint model and the joint orthogonal decomposition allow a stability analysis of the whole system, such that convergence properties in motion and force spaces are obtained. The effectiveness of our proposal is experimentally shown.

Fuzzy vs Nonfuzzy in 2D Visual Servoing for Robot Manipulators

In this paper we consider the tracking control problem of planar robots manipulators via visual servoing in the presence of parametric uncertainties associated with the robot dynamics and the camera parameters. An image–based visual servo control is developed using a Takagi–Sugeno (T–S) fuzzy model. The design includes an image coordinate velocity observer. To the best knowledge of the authors such a proposal remains hitherto unpublished. The new scheme is compared experimentally with two different non–fuzzy algorithms showing the good performance and advantages of the complete system.

Simplied Methodology for Obtaining the Dynamic Model of Robot Manipulators

The main goal of this manuscript is to present a simplification of the Euler-Lagrange methodology, which allows us to simplify the obtaining of dynamic model of a robot using the intrinsic properties of dynamic model, which allows to reduce the computation time when the model is programmed. Using the L 2 norm, the proposed methodology is compared with the Euler-Lagrange methodology for obtaining a performance index to determine the proposed simplification efficiency. The main contribution of this manuscript is to present a methodology to obtain the completely symmetric dynamic model.

Fuzzy logic control of a robot manipulator in 3D based on visual servoing

Abstract Visual servoing is a useful approach for robot control. It is specially attractive when the control objective can be stated directly in image coordinates. Fuzzy control is a practical alternative for a variety of challenging control applications since it provides a convenient method for constructing nonlinear controllers via the use of heuristic information, which for instance may come from an operator who has acted as a “human-in-the-loop” controller for a process. Fuzzy control strategy offers an alternative approach for many conventional systems, which has certain advantages over the other techniques. In this work, we proposed a control algorithm for a robot manipulator, which combines fuzzy logic with 3D visual servoing. For implementation only image coordinates are required. Simulation results show the good performance of the complete system.

Telemanipulation of cooperative robots: a case of study

ABSTRACT This article addresses the problem of dexterous robotic grasping by means of a telemanipulation system composed of a single master and two slave robot manipulators. The slave robots are analysed as a cooperative system where it is assumed that the robots can push but not pull the object. In order to achieve a stable rigid grasp, a centralised adaptive position-force control algorithm for the slave robots is proposed. On the other hand, a linear velocity observer for the master robot is developed to avoid numerical differentiation. A set of experiments with different human operators were carried out to show the good performance and capabilities of the proposed control-observer algorithm. In addition, the dynamic model and closed-loop dynamics of the telemanipulation is presented.