Industrial Robot: An International Journal

Purpose – The purpose of this paper is to describe development and application of an iterative learning control (ILC) scheme for a tracking problem. The control objective is to achieve accurate tracking of a desired trajectory which is the path taken by a laser beam.

Design/methodology/approach – It involves formulating an ILC scheme in two-dimensional (2D) representation on mathematical model of two degrees of freedom platform. The scheme was tested and fine tuned with the help of simulation results on that model. Subsequently, an experimental setup was prepared by mounting a camera on a six degree of freedom hexapod, M-850 from Physik Instrumente. The experimental setup was made to track an arbitrarily positioned laser spot on a screen. For this purpose, a simple image processing module was also developed. The underlying algorithm implemented learning and tracking modes.

Findings – The tracking performance of the scheme is impressive. The simulations as well as practical results show that the scheme is robust and simple to implement.

Research limitations/implications – The limitation is the time spent in learning mode before the control function is applied to the system under consideration. This, however, is an inherent aspect in any ILC scheme.

Practical implications – Its application can be in manufacturing processes, robotics, target tracking and even in bio engineering where growth of some specific bacteria population could also be tracked.

Originality/value – Little work, with practical implementations, has been reported in ILC. The authors perceive that this scheme has the potential to simplify a great number of control problems especially in the field of robotics and trajectory tracking.