Full Content is available to subscribers

Subscribe/Learn More  >

Advanced Hydraulically Actuated Patient Transfer Assist Device

[+] Author Affiliations
Heather C. Humphreys, Wayne J. Book

Georgia Institute of Technology, Atlanta, GA

Paper No. FPNI2014-7821, pp. V001T01A004; 8 pages
  • 8th FPNI Ph.D Symposium on Fluid Power
  • 8th FPNI Ph.D Symposium on Fluid Power
  • Lappeenranta, Finland, June 11–13, 2014
  • Conference Sponsors: Fluid Power Net International (FPNI), Lappeenranta University of Technology, Finland
  • ISBN: 978-0-7918-4582-0
  • Copyright © 2014 by ASME


A new, advanced patient transfer device is being developed for moving mobility limited patients, for example, from a wheelchair to a bed or a floor into a chair. Current market patient lift devices are antiquated and insufficient for customer needs, with only one actuated degree of freedom. The high power to size ratio of hydraulic actuation makes it suitable for moving larger, heavier patients. We have developed a prototype pump-controlled hydraulically actuated patient transfer device that is more maneuverable and agile, using multiple actuated degrees of freedom. We are also working toward developing a more intuitive and safe caretaker interface and control strategy.

We have performed an extensive needs assessment; these are a few associated key design requirements relevant to this presented work. A compact package is needed for ease of maneuvering the patient around obstacles in an uncertain environment. The device is capable of producing large forces, so it is desirable for the controller to minimize any unintentional large external contact forces, or provide force feedback. In this system, the caretaker and device work together to maneuver a complex payload, a human body; the operator’s mental workload must be minimized. With humans in the device workspace, safety and stability are necessary, including environment interactions.

This new application presents several challenges related to the hydraulic control. First, we are using a separate bidirectional fixed displacement pump with a reversible brushed DC motor for each degree of freedom. The low level control involves obtaining desirable response from each motor-pump-actuator system, while compensating for significant static friction. At a higher level, we are testing several approaches to attain the desired intuitive control and desired dynamics, and minimize the operator workload. First, we are developing a coordinated control using a force input, such that the operator simply pushes on the device in the desired direction of motion. We are testing several different controllers to attain the desired dynamics. This paper presents the design of the machine, the proposed control structures as applied to this application, operator interface options, some preliminary results, and future work.

Copyright © 2014 by ASME



Interactive Graphics


Country-Specific Mortality and Growth Failure in Infancy and Yound Children and Association With Material Stature

Use interactive graphics and maps to view and sort country-specific infant and early dhildhood mortality and growth failure data and their association with maternal

Citing articles are presented as examples only. In non-demo SCM6 implementation, integration with CrossRef’s "Cited By" API will populate this tab (http://www.crossref.org/citedby.html).

Some tools below are only available to our subscribers or users with an online account.

Related Content

Customize your page view by dragging and repositioning the boxes below.

Related eBook Content
Topic Collections

Sorry! You do not have access to this content. For assistance or to subscribe, please contact us:

  • TELEPHONE: 1-800-843-2763 (Toll-free in the USA)
  • EMAIL: asmedigitalcollection@asme.org
Sign In