Adaptive force-position control for teleoperated manipulators

An adaptive controller with self-tuning can be designed for teleoperated robotic manipulators by determining a time-series model for the function of the teleoperator. Specifically, the position and force exerted by the operator are modelled for determining the derived values for the trajectory of the end-effector of the manipulator. Thus, the adaptive controller can be designed by following the steps which have previously been presented for the controller design of the gross motion

A review of friction models in interacting joints for durability design.

This paper presents a comprehensive review of friction modelling to provide an understanding of design for durability within interacting systems. Friction is a complex phenomenon and occurs at the interface of two components in relative motion. Over the last several decades, the effects of friction and its modelling techniques have been of significant interests in terms of industrial applications. There is however a need to develop a unified mathematical model for friction to inform design for durability within the context of varying operational conditions. Classical dynamic mechanisms model for the design of control systems has not incorporated friction phenomena due to non-linearity behaviour. Therefore, the tribological performance concurrently with the joint dynamics of a manipulator joint applied in hazardous environments needs to be fully analysed. Previously the dynamics and impact models used in mechanical joints with clearance have also been examined. The inclusion of reliability and durability during the design phase is very important for manipulators which are deployed in harsh environmental and operational conditions. The revolute joint is susceptible to failures such as in heavy manipulators these revolute joints can be represented by lubricated conformal sliding surfaces. The presence of pollutants such as debris and corrosive constituents has the potential to alter the contacting surfaces, would in turn affect the performance of revolute joints, and puts both reliability and durability of the systems at greater risks of failure. Key literature is identified and a review on the latest developments of the science of friction modelling is presented here. This review is based on a large volume of knowledge. Gaps in the relevant field have been identified to capitalise on for future developments. Therefore, this review will bring significant benefits to researchers, academics and industrial professionals

Reduced Order Model and Decoupled Control Architecture for Two Manipulators Holding an Object,"

A dynamical model and a control architecture are developed for the closed chain motion of two N-joint manipulators holding a rigid object in a three-dimensional workspace. Dynamic and kinematic constraints are determined and combined with the equations of motion of the manipulators to obtain a dynamical model of the entire system in the joint space. Reduced order equations of motion and afunctional relation for the generalized contact forces are derived. The problem of solving the reduced order model for the forward and inverse dynamics is discussed. Control laws are determined for the reduced order model so as to decouple the force and position (velocity) controlled degrees of freedom (DOF). A simulation example is presented to illustrate the approach. I Introduction Many benefits can be obtained by applying two cooperating manipulators to industrial manufacturing. A typical example is in a flexible assembly, where the manipulators join two parts into a rigid product requiring a coordinated assembly of the work pieces. Two cooperating manipulators can also be used in material handling, e.g., transporting objects beyond the load carrying capacity of a single manipulator. However, the addition of a second manipulator leads to an inherently complex system. Several key research issues and open problems associated with systems of coordinated robotic manipulators are discussed i