An Active Handrest for Precision Manipulation and Ergonomic Support

In this research we are trying to expand the precision of small finger motions to arbitrarily large workspaces using an Active Handrest. We anticipate the user’s intended motion by measuring their reaction forces on the handrest and by measuring the motions of the grasped tool. The Active Handrest then provides support forces and motions to help the user complete their task, as indicated in the Active Handrest concept image below. The device can be used to aid surgeons and artists/sculptors, and could be used for hand/arm rehabilitation, as an assisstive device for people with hand tremor (e.g., those with cerebral palsy or those recovering from a stroke), to aid in electronics refurbishment, or even for defusing bombs.

Active Handrest Concept
 

Because the handrest moves wherever the user is performing their precision task, it also provides ergonomic support that can reduce fatigue… hence also aiding in performing precision tasks over extended period of time. An image of our current Active Handrest prototype and control scheme is shown below.

Initial Active Handrest PrototypeActive Handrest Control Diagram


Movie showing the Active Handrest input control modes: Position Input and Force Input. Here is a LINK to the YouTube site showing the above movie).


Movie showing the Active Handrest used in a simple circle drawing task. The handrest’s motion is restricted to 5 mm/s during drawing, but can move at 25 mm/s (or faster) in between locations where precision is needed. Here is a LINK to the YouTube site showing the above movie).

A study showing a performance comparison between the active handrest and other traditional hand support methods is described in the paper below that was submitted to the 2010 Haptics Symposium. These initial experiments show the promise of our approach. Further investigations aimed at improving the control of the device are ongoing.

The system is currently only capable of providing support for planar tasks. Now that the general concept has been validated through initial user testing, we will be extending the device to provide support for more general spatial motions. We are also interested in investigating the Active Handrest with current telerobotic systems and with traditional co-manipulation techniques such as virtual fixtures.

Related Publications and Media Coverage


Related publication

  • M. Nambi, W. R. Provancher, and J. J. Abbott, “ On Precise Human Force Control of Admittance-Type Devices,” Advanced Robotics, 25, 2011, pp. 629–650.
 

Media Coverage

This work is supported by the National Science Foundation under grant numbers IIS-0746914 and DGE-0654414.


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