Control of a shape memory alloy actuation apparatus
US8756933B2 · kind B2 · utility
Assignee
Inventors
Key dates
| Filing date | Dec 3, 2008 |
| Grant date | Jun 24, 2014 |
| Priority date | — |
| Expiry date | Sep 8, 2031 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG03B5/00
- WIPO fieldOptics
- WIPO sectorInstruments
Abstract
An SMA actuation arrangement comprises: an SMA actuator arranged on contraction caused by heating to drive movement of a movable element relative to a support structure; a current source operative to supply drive current through the SMA actuator to heat the SMA actuator; and a detector circuit operative to detect a measure of the resistance of the SMA actuator. While detecting a measure of the resistance of the SMA actuator and controlling the drive current on the basis of the measure of the resistance of the SMA actuator; there is derived a measure of an electrical characteristic of the SMA actuator that is representative of the ambient temperature. While applying closed-loop control an offset is added to the control signal which reduces the steady-state value of an error between the measure of the resistance of the SMA actuator and a target value. While applying open-loop control, the control signal is generated taking into account the electrical characteristics of the SMA actuator measured during a calibration stage.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.