Engineered to resist vibration, the sensor uses a fiber-filled, temperature-resistant, and dustproof plastic body sealed to an IP65 rating. It's designed for reliable operation in temperatures from –40 to 150°C. Sensor mounting flanges contain elongated holes that simplify installation and allow easy mechanical adjustments. The push-on mechanical coupling simplifies linking the sensor to the handlebar pivot and also minimizes any hysteresis from excess play.

If the PT traveled only on flat surfaces, then any leaning by the rider would command a turn. However, a person may "lean" while standing upright as when the Transporter travels along a sloped bank or hits a bump in the road. So the balance sensor assembly (BSA) must sense the angle of the terrain as well as the rider's body position. The dual-controller system has two digital signal processors, two dual-axis accelerometers for tilt-angle measurement, and five angular-rate sensors using MEMS-based gyroscopes.

The gyroscopic angular-rate sensors monitor rotation by measuring acceleration from Coriolis effect. A micromachined oscillating accelerometer within the angular-rate sensor experiences this effect when it is rotated. The output of the accelerometer is then processed to provide the rate of rotation.

The BSA detects forward or backward lean, left and right lean, and rotation left or right. These motions are often referred to as pitch, roll, and yaw respectively. It checks, cross-checks, and acts on all inputs 100 × a second — many times faster than a rider can react.

Cross-checks assure that the BSA is operating properly. If one controller board, or its associated battery, motor windings, or wiring breaks, the second controller takes over all functions. The system notifies the rider of the failure and shuts down gracefully bringing the rider to a safe stop.

MAKE CONTACT
Novotechnik U.S., (508) 485-2244, novotechnik.com
Segway Inc., (866) 473-4929, segway.com