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Meso–Scale Hydraulic Systems

Project Objective

We want to develop a low pressure, semi-distributed, quasi–disposable hydraulic system for bio-inspired platforms. We will focus on doing this at the mezzo scale, while also incorporating the possibility of dangle. The hydraulic system should be lightweight, and have a high power density. Some potential applications of such a system include morphing the wing of a UAV, swinging a crab-like leg of a UGV, or fluttering the cuttlefish-like fins of a UUV.

Project Description

Cornell University along with AST Engineering, proposes to investigate new small configurations of hydraulic actuators. This is being done for many of the same reasons that hydraulic actuation becomes such an attractive solution for large scale systems. Some of these reasons include more centrally located transduction, with numerous distributed actuation systems.

While the value for this approach to actuation systems remains the state of the art for industrial applications, increasingly, aircraft are moving to becoming more electric. This has called for increasing use of EMAs (electro-magnetic actuators). The issue with this approach is that EMAs require individual transduction at every degree of freedom needed for actuation. This approach impedes our capacity for redundancy in system design, and can increase system weight, thus limiting the number of actuators used in a system. The EHA (Electro–Hydro–static Actuation) developed by Moog integrated the benefits of hydraulics with an electrically driven actuator. We propose to investigate a device with semi–localized hydraulic fluid.

We will explore the concept using some of Cornell's Reuleaux models of pumps and steam engine concepts to inspire a new type of device that will provide an alternative form of energy. This new source of power would be developed to drive distributed hydraulic actuators, especially for ground robotic systems that have hitherto used batteries for supply power. This could enable new forms of bio–inspired robotic systems, based on legged actuation or supplies that could turn torsional actuators and manipulators to offer greater mission capabilities.

  • Pump requirements for localized hydraulic actuation
  • Weight saving with reduced pressures, use of non–traditional hydraulic fluids — water based instead of oil
  • Development of pump pulse–width modulation systems
  • Development of new types of EMA controlled valves
  • Development of a chemo–mechanical pump, an integration of a hydraulic compressor with an internal combustion engine
  • Analysis of systems to determine weight and power saving for small scale hydraulic systems

We are targeting a bio–inspired platform such as a UAV, UUV and/or UGV project that would benefit from this vision of an actuation system. Cornell University is currently engaged in the study of a cuttlefish–like fin for underwater vehicle applications. This type of actuation would involve numerous distributed actuators, which could be demonstrated with EMA technology and be an excellent candidate for semi–distributed hydraulics. We will focus the effort of a semi–distributed, low pressure hydraulic system on this application.

Project Video(s)

Funding Agencies

  • Defense Advanced Research Projects Agency
  • Moog, Inc.