Putting cars in to motion

April 03, 2014 // By Jari Nieminen, Murata
MEMS sensors are increasingly providing a crucial element in closed-loop automotive control systems.

Control systems, of all types employ closed-loops that rely on feedback in a bid to assess cause and effect; once the effect has been assessed, the cause (or stimulus) can be modified, a reiterative process that improves the time to result exponentially. Not surprisingly this closed-loop approach to control enables many applications, but it is also now being applied extensively to improve the efficiency of a growing number of others.

A key element to this trend is the availability of reliable, responsive and robust sensors, which form a critical link in the feedback chain. Sensors, in general but particularly those that rely on a measurable, physical change in the sensor material (caused by exposure to the condition/property being measured) are commonplace, often passive and have well defined limitations. The introduction of micro electro-mechanical systems, or MEMS, however, is breaking down these barriers to how, where and for what sensors can now be used.

MEMS in Automotive

Probably the most widely reported, researched and developed application for MEMS sensors is the measurement of inertial change in the form of acceleration and orientation (accelerometers and gyroscopes, respectively). Their tiny dimensions and robust construction mean MEMS sensors can be used in harsh environments where space is limited, to create use-cases that would not be possible without them.

In automotive systems, MEMS sensors now enable a growing range of control solutions that deliver greater efficiency and safety in vehicles; MEMS now enable safety features such as airbags, antilock braking systems, electronic stability programs and electronically controlled suspension, as well as advanced driver-assist systems such as hill start assist and electric parking brake features, lane departure warning, automatic cruise control and more.

Broadly speaking, MEMS sensors in automotive are used to enable or enhance safety; typically, in passive safety systems, such as airbags, the sensor acts as a trigger. Conversely, active systems, such as antilock braking, active suspension or stability control, require more sensitivity and

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