Using Wheel Pulse Transducers for Autonomous Vehicle Tracking

Michigan Scientific Corporation’s Wheel Pulse Transducer (WPT) is a compact encoder system that is designed to attach to the wheel of a vehicle.  Encoder signals from the WPT can be used to calculate the angular velocity and angular position of a wheel.  These measurements are commonly used to track the position of a vehicle for applications such as fleet management and autonomous vehicle tracking.

Sensor Description

The assembly is designed to mount quickly and easily to a vehicle wheel. Its compact and light weight design consists of electronics in a rugged housing. The encoder module is attached to a wheel plate and mounted on the customer wheel using collet lug extensions. The adapter plates and collet lug extensions come in a variety of sizes and configurations to meet any standard wheel dimension. A Magnetic Vehicle Stator Restraint and restraining rod are used to hold the encoder module stator in place while the sensor is being used on the vehicle. Due to the nature of vehicle testing, the WPT has been designed to be very rugged and can accept rotary seals for an IP67 rating, making it ideal for testing in rainy, snowy, or dirty environments. 

Dead Reckoning

Autonomous vehicles rely on Global Navigation Satellite System (GNSS) technology to track their position but these systems can fail in urban, indoor, or underground environments.  Dead reckoning systems can be used to overcome the downfalls of GNSS in challenging environments.

Michigan Scientific’s WPT uses a 512 pulse per revolution (ppr) optical encoder.  The encoder has two channels in quadrature so it can sense rotational direction.  The encoder electronics combine the “Exclusive OR” of the two channels to double the resolution of the encoder, bringing the resolution to 1024 ppr.  Using a WPT system on both sides of a vehicle allows the user to measure and compensate discrepancies due to curves and cornering.

The WPT system can be used as an instrument to help dead reckoning systems, or it can be used to test and validate the accuracy of accelerometer-based systems.

Autonomous Vehicle Tracking

Automation is helping improve productivity in many industries, but there are some fields where implementing autonomous vehicles is challenging.  In areas where GNSS tracking is not available, other technologies such as Wheel Pulse Transducers or accelerometers must be used to track the location of vehicles.  WPT systems can be used to track the position of autonomous forklifts inside of warehouses, or autonomous underground mining equipment.

If you are interested in learning more about how the Wheel Pulse Transducer can be used for your application, please contact a Michigan Scientific Representative today.