From its first introduction in 2001, the distinctive two wheeled Segway Personal Transporter has taken the world by storm. The PT removes the strain from workers and leisure users that would otherwise need to travel long distances on foot and it’s now seen everywhere from airports to golf links.
The second generation PT is a futuristic self balancing transportation device with highly sophisticated motion and stabilisation technology that uses the rider’s natural body movements to propel and steer the vehicle. With highly efficient operation the vehicle can hit 12.5 mph and covers a range of 24 miles.
The Segway PT uses its LeanSteer steering system to allow the riders body movement to guide the vehicle whilst the Segway Smart Motion (SSM) controller uses the same information to maintain motion and direction with complete dynamic stability through its balance sensor assembly (BSA) which has integral solid state rate gyro and tilt sensors.
In operation, the rider simply moves forwards, backwards and to each side to propel and steer the PT in the corresponding direction whilst the highly developed control system ensures that bumps, camber or uneven slopes which may affect the riders body position are fully compensated to ensure completely smooth operation.
Clearly, to guarantee the safe operation of the PT and maintain its total reliability, long life and competitive costs, the choice of components are of paramount importance. The LeanSteer system uses the compact and robust SP2880 angular position sensor.
The SP2800 is located at the pivoting base of the handlebar shaft, providing high-bandwidth angular position feedback that effectively measures the rider’s body angle which is used as a reference to generate the lateral acceleration required to balance the PT and its rider.
For this application, the conductive plastic technology SP2880 sensor is a fully redundant design for maximum reliability featuring two completely independent measuring systems, each with precious metal wipers and dual voltage outputs. The sensor provides a 140 degree electrical range with are solution of less than 0.01 degrees, linearity to +/- 0.3% and repeatability ≤ 0.03 degrees.
The 28mm diameter sensor is just 17mm long, built from high quality temperature resistant plastic and features a push-on shaft coupling and slotted flange mounting for fast installation. The highly durable housing is IP65 rated for dust and water spray protection and has an operating temperature range of -40 to 150ºC, allowing its use in extreme weather conditions. The rated life is over 50 million cycles and with a current consumption of less than 1mA, the SP2880 sensor more than satisfies the requirements for minimal energy use on the battery powered Segway PT.
The 2880 series is a part of a wide range of contacting and non-contacting angular position sensors available from Novotechnik that are stocked and fully supported in the UK and Ireland by Variohm EuroSensor. This application illustrates Novotechnik’s capability to provide standard products with customisation to adapt to the exact demands of the customer’s application.
