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

Xiaoping Ouyang, Shuo Ding, Boqian Fan, Perry Y. Li, Huayong Yang

Research output: Contribution to journalArticlepeer-review

34 Scopus citations


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 2.4 kW at 13,000 rpm, is used as the prime mover. The engine drives a high speed (10,000 rpm) 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 1.45 kW and a weight of 16.6 kg. Experimental testing of the prototype confirms the dynamic model and the output capacity of the CHPU.

Original languageEnglish (US)
Pages (from-to)68-75
Number of pages8
StatePublished - Sep 1 2016

Bibliographical note

Funding Information:
The work was supported by the National Natural Science Foundation of China (Grant No. 51275450 ), National Basic Research Program of China (973) (Grant No. 2014CB046403 ), and Science Fund for Creative Research Groups of National Natural Science Foundation of China (Grant No. 51521064 ).

Publisher Copyright:
© 2016 Elsevier Ltd


  • Exoskeleton robot
  • High specific power
  • Hydraulic power unit
  • Model
  • Parameters identification


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