The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
Jun. 24, 2014
Filed:
Dec. 03, 2008
Richard Topliss, Cambridge, GB;
Robert John Leedham, Cambridge, GB;
David Charles William Richards, Milton, GB;
Thomas Matthew Gregory, Caldecote, GB;
Richard Topliss, Cambridge, GB;
Robert John Leedham, Cambridge, GB;
David Charles William Richards, Milton, GB;
Thomas Matthew Gregory, Caldecote, GB;
Cambridge Mechatronics Limited, Cambridge, GB;
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.