Electrically actuated antiglare rear-view mirror based on SMA actuator

As for the experience achieved by CRF in the development of SMA actuators some new design approach have been defined. First the active wires’ working condition is optimal when the acting forces are kept constant during the actuation phase, and separated from the external overloads impressed by the user. The second aspect is that the efficiency of the wire transformation is very low, so good applications should be focused on occasionally used devices. The antiglare manual mechanism placed in the internal rear-view mirror of a car excellently fits both the aspects. An antiglare rear-view mirror is a system capable to detect a glare situation during the night drive and then automatically switch the mirror plane in order not to distract the driver. The low forces required, the silent and bi-stable movement are suitable for the use of a SMA actuator in this application. In the first part of the paper the conceptual design is illustrated and a preliminary overview of the working principle is given. Subsequently a series of considerations regarding the kinematics and the layout of electronic sensors in order to realize a fully controlled mechatronic prototype has been done. At the end of the paper the description of the realization of a working prototype is presented. The prototype of the EAGLE (Electrically Actuated antiGLare rEar-view mirror) system confirmed experimentally that such a device can pass fatigue and functional tests, and thus represents a chance to spread the use of SMA devices in the automotive field.