Performance analysis of Elastic Band based time optimal control formulations for industrial robots

Tid: Må 2019-06-24 kl 13.00 - 14.00

Plats: Seminar room (Rumsnr: A:641), Malvinas väg 10, Q-huset, våningsplan 6, KTH Campus

Respondent: Jonas Hongisto

Opponent: Simon Lindståhl

Handledare: Giancomo Spampinato, ABB Robotics

Examiner: Elling Jacobsen

Abstract: Industrial robots are becoming an integral part of the production industry. Efficient operation with respect to fast movements is critical to increase the economic benefits of automating the production line. Facilitating near optimality with regards to time hashigh computational demands however and multiple frameworks have been suggested to remedy this. In this thesis we consider one of these frameworks, namely the elastic band framework. We investigate how the elastic band time optimal control framework performs regarding computational time for point-to-point movements on a SCARA type robot with three revolute and one prismatic joint. We compare an unconstrained elastic band formulation with a constrained formulation in the open loop, along with simulating performance in the closed-loop. We show that a constrained formulation which considers the sparseness of underlying matrices in the optimization problem has the lowest computational time. Additionally, we show that the unconstrained formulation benefits from early stopping. Finally, we show that a controller implementing this formulation can be used in a model predictive controller, although the computational time is still too high for commercial use on the hardware used in testing.