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  1. Inclination sensors
  2. Introduction and history

Introduction and history

From switch to sensor technology

The technology for tilt or inclination sensors has evolved over the years from simple tilt switches to sophisticated fully electronic sensors that combine multiple sensing technologies.

Tilt switch

Many years ago, these devices were not sensors but switches that consisted of a rolling ball with a conductive plate underneath. The switches were designed such that a sufficient level of tilt would allow the ball to leave its initial position with the help of externally acting physical forces and form an electrical connection with the plate. This signal could be then be used either for switching functions or as an indicator.

For example, such sensors were used on the outside of trains to detect cross acceleration.As soon as the switch signalled a curve, the wheel flange could be lubricated.

Liquid-based sensors

In addition to simple tilt switches, liquid-based sensors were becoming increasingly common. For the first time, this technology was worthy of being called “tilt sensor”.

Left: off position, right: inclined position
1) Common electrode
2) Right and left electrode (+/-)
3) Conductive fluid
4) Resulting tilt angle
5) Common connections

Fluid-filled tilt sensors contained resistive or capacitive liquids inside a sealed cavity. As the capsule tilts end to end, the liquid flows to one side or the other which changes the resistance or capacitance of an internal circuit, and the output of the circuit could be monitored directly. It could be amplified or translated into other output types. While these sensors could provide accurate and reliable inclination data in many applications, they had several weaknesses, including a slow time response, susceptibility to vibration and limited lifespans.