Smarter Thanks to support from one of Germany's Innovation Relay Centres, and funding from the European Union, three companies from across Europe have been able to collaborate to develop an advanced inertial microsensor for the European market. Accelerometers, as their name implies, measure the rate of change of velocity, producing an electronic signal which can be measured or used to control a process. Common applications include the activation mechanisms of automotive seat belts and air bags, where the accelerometer senses sudden deceleration and causes these safety devices to engage. These sensors employ a mechanism that is analogous to stretching a spring.
Acceleration stretches the spring, higher acceleration stretches the spring further.
Measure the lengths of the deformations and acceleration can be determined. Add in a known initial velocity and the time element and simple physics allows us to calculate the distance travelled. Make the system three dimensional by adding sensors to monitor longitudinal and rotational movement and we have what is, in theory, the basis of an automatic navigation system. The way to achieve the much greater precision required is to use 'closed loop' inertial microsensors. In these, continuous electrical feedback from the signal output to the sensor probe exactly balances the incoming mechanical forces, eliminating inaccuracies and allowing the tiniest changes to be detected.