Cambridge Mechatronics Limited

Thomas Matthew Gregory

Richard John Topliss

Andrew Benjamin David Brown

Anthony Hooley

Dominic George Webber

Robert John Leedham

Daniel John Burbridge

David Charles William Richards

Richard Topliss

Paul Raymond Windle

Igor Gotlibovych

John Grayley

Mark George Easton

David Charles Wilson Richards

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.

Control of a shape memory alloy actuation apparatus

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Caldecote, United Kingdom

Thomas Matthew Gregory