Accession Number:

ADA282891

Title:

Legged Vehicle for Underwater Mobile Operations

Descriptive Note:

Progress rept.

Corporate Author:

MASSA PRODUCTS CORP HINGHAM MA

Personal Author(s):

Report Date:

1994-07-05

Pagination or Media Count:

10.0

Abstract:

This report summarizes technical information gained from an investigation into utilizing SMA actuators as muscle components for the biologically based lobster system to be developed under this project. In order for the SMA actuators to be of value in controlling leg motion of the lobster they must be able to contract and relax in a controlled manner much like muscles. SMA wires made of Nitinol do contract when heated and relax when cooled. The heating mechanism in this application is directly related to current density passed through the wire. If a large number of cycles are required, as in our application, the contraction should be limited to about 3. This can provide a cycle life of millions provided that proper protection from overstressing, overstraining, and overheating are designed into the system. SMA contraction time can be quite fast 0.1 seconds or less depending on the current pulse amplitude and width. SMA wires are very strong relative to their size. A 4 contraction can exert stresses of 25,000 psi. Control of each actuator requires that current pulses of proper amplitude and duration be applied at the correct times in order to not overheat the wires. Proper control of SMA wires for this application will require sensory feedback

Subject Categories:

  • Cybernetics
  • Test Facilities, Equipment and Methods
  • Bionics

Distribution Statement:

APPROVED FOR PUBLIC RELEASE