Energy-efficient and high-precision control of hydraulic robots. (April 2019)

• Record Type: Journal Article
• Authors: Koivumäki, Janne; Zhu, Wen-Hong; Mattila, Jouni
• Is Part Of: Control engineering practice. Volume 85(2019)
• Page Start: 176
• Page End: 193
• Publication Date: 2019-04
• Subjects: Hydraulic robots -- Nonlinear control -- Stability analysis -- Independent metering -- SMISMO control -- Energy efficiency; Automatic control -- Periodicals; 629.89
• DOI: 10.1016/j.conengprac.2018.12.013
• Languages: English
• ISSNs: 0967-0661

Abstract

Abstract: In addition to high-precision closed-loop control performance, energy efficiency is another vital characteristic in field-robotic hydraulic systems as energy source(s) must be carried on board in limited space. This study proposes an energy-efficient and high-precision closed-loop controller for the highly nonlinear hydraulic robotic manipulators. The proposed method is twofold: 1) A possibility for energy consumption reduction is realized by using a separate meter-in separate meter-out (SMISMO) control set-up, enabling an independent metering (pressure control) of each chamber in hydraulic actuators. 2) A novel subsystem-dynamics-based and modular controller is designed for the system actuators, and it is integrated to the previously designed state-of-the-art controller for multiple degrees-of-freedom ( n -DOF) manipulators. Stability of the overall controller is rigorously proven. The comparative experiments with a three-DOF redundant hydraulic robotic manipulator (with a payload of 475 kg) demonstrate that: 1) It is possible to design the triple objective of high-precision piston position, piston force and chamber pressure trackings for the hydraulic actuators. 2) In relation to the previous SMISMO-control methods, unprecedented motion and chamber pressure tracking performances are reported. 3) In comparison to the state-of-the-art motion tracking controller with a conventional energy-inefficient servovalve control, the actuators' energy consumption is reduced by 45% without noticeable motion control (position-tracking) deterioration.