Development of a novel compact hydraulic power unit for the exoskeleton robot

• Published in: Mechatronics (Oxford) 2016-09, Vol.38, p.68-75
• Main Authors: Ouyang, Xiaoping, Ding, Shuo, Fan, Boqian, Li, Perry Y., Yang, Huayong
• Format: Article
• Language: English
• Subjects: Exoskeleton robot; High specific power; Hydraulic power unit; Parameters identification
• ISSN: 0957-4158; 1873-4006
• DOI: 10.1016/j.mechatronics.2016.06.003

•A novel compact hydraulic power unit (CHPU) powered by an IC engine is proposed.•The piston pump with 10,000rpm is employed for matching the engine well in CHPU.•A spring reservoir assists the pump to prevent the cavitation and contamination.•CHPU has a high specific power and can be easily integrated into robot systems.•The dynamic model of the CHPU is proposed and validated by the prototype test. Exoskeleton robots require powerful and lightweight power supplies. Because of its high power-to-mass ratio and fast response, hydraulic systems can meet the requirement for locomotion robots. In this paper, a novel compact hydraulic power unit (CHPU) is proposed. A two-stroke IC engine, with a rated power of 2.4kW at 13,000rpm, is used as the prime mover. The engine drives a high speed (10,000rpm) piston pump to allow the engine to operate at high power. A spring loaded reservoir has been developed to prevent the pump intake from cavitation and contamination. The payload flow rate is indirectly estimated using the displacements of the actuator. A Ragone plot analysis shows that the CHPU can maintain a high specific power over a long duration. A dynamic model for the CHPU has been developed based upon simplified engine operating characteristics and a set of experimentally identified parameters. A prototype of the CHPU has been constructed with a rated power of 1.45kW and a weight of 16.6kg. Experimental testing of the prototype confirms the dynamic model and the output capacity of the CHPU.