Energy optimal control of an over-actuated hybrid feed drive under variable-frequency disturbances —​ with application to machining. (July 2020)

• Record Type: Journal Article
• Authors: Duan, Molong; Ramani, Keval S.; Okwudire, Chinedum E.
• Is Part Of: Control engineering practice. Volume 100(2020)
• Publication Date: 2020-07
• Subjects: Energy efficiency -- Control allocation -- Gain scheduling -- Machining -- Feed drive; Automatic control -- Periodicals; 629.89
• DOI: 10.1016/j.conengprac.2020.104442
• Languages: English
• ISSNs: 0967-0661

Abstract

Abstract: Machine tool feed drives are often subject to variable-frequency disturbance (cutting) forces due to varying spindle speeds or cutting tools. A proxy-based control allocation method has been proposed for energy optimal control of over-actuated systems (i.e., systems with more actuators than the number of outputs to be controlled). It has been applied to an over-actuated hybrid feed drive, consisting of a linear motor drive coupled to a screw drive, and its effectiveness has been demonstrated under fixed-frequency disturbance forces. This paper discusses the fundamental limit of the fixed-frequency approach and extends the proxy-based control allocation method to account for variable-frequency disturbance forces via a linear parameter-varying formulation. The controller gains are optimized using linear matrix inequality and scheduled as a function of disturbance frequency. Significant improvements in energy efficiency are demonstrated in simulations and experiments using the proposed gain-scheduling approach compared to the existing fixed-frequency approach.