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Issue #200 March 2007
Inertial Rolling Robot
by Jeff Bingham & Lee Magnusson
Start | Electronics | Drive Motor | Servo Motor | Pressure Sensor | Software | DC Drive Motor Control | Servo Motor Control | Mechanical Components | Manufacturing | Assembly | Findings | Sources & PDF
PRESSURE SENSOR
We used a Freescale Semiconductor MPX5100A absolute pressure sensor (with
a range from 0 to 16.7 psi) so the inflated ball structure can sense the
environment. When the ball hits a barrier, it can be picked up as a pressure
transient.
The absolute pressure sensor measures pressure with respect to a perfect vacuum. Thus, the sensor reads both atmospheric and ball pressure. Since atmospheric pressure at sea level is 14.7 psi and the ball may be inflated with 1 psi, the sensor has only a small range that it can sense. However, because impacts of the ball produce both positive and negative changes in pressure, the sensor is effective at detecting collisions. This sensor is easy to interface with the microcontroller: VOUT from the sensor is connected directly to an ADC port. Decoupling and filtering capacitors are recommended in the MPX5100A’s datasheet.
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