In order to achieve higher energy efficiency for hydraulic systems the Load Sensing (LS) systems, i.e. a Variable Displacement Pump (VDP) with hydro-mechanical control system, can be considered as a state-of-the-art solution. However, as is well known, these traditional hydraulic LS-systems are usually characterized by difficulties in tuning, which can lead to system stability problems. In our previous studies, we have developed a high precision motion control for hydraulic manipulators with separate meter-in meter-out controlled hydraulic actuators. Our control approach was based on the Virtual Decomposition Control (VDC) approach that ensured high motion tracking performance while rigorously guaranteeing the system stability. In this paper, we propose both energy-efficient and high performance nonlinear model based motion control scheme that utilizes the developed servocontrolled Electric Load Sensing (ELS) system for hydraulic robotic manipulators. Experimental results are presented with the proposed ELS-controlled VDP and hydraulic manipulator lifting servoactuator that utilized a separate meter-in meter-out flow control scheme.
A secure energy-efficient access control scheme for wireless sensor networks based on elliptic curve cryptography
