Wheel Pulse Transducers and 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 rotational velocity, the angular position, and the direction of rotation of a wheel. These measurements are commonly used to track the position of a vehicle for applications such as electric vehicle development and autonomous vehicle tracking.

Autonomous Vehicle Tracking

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. 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. Additionally, the WPT system can be used to test and validate the accuracy of accelerometer-based systems.

WPT 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 WPT is mounted to the wheel via Quick Connect Lug Nut Collets or Extended Lug Nuts. The adapter plates and Quick Connect Lug Nut Collets 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. With rotary seals for an IP67 rating, the WPT is ideal for testing in rainy, snowy, or dirty environments.

Encoder Signal Conditioners

WPT optical encoder resolutions up to 5,000 pulses per revolution (ppr) are available. Standard resolutions include 360 ppr, 512 ppr, 1024 ppr, and 5,000 ppr. Additional resolutions are available upon request. All encoder choices have four standard encoder outputs: A, B, I, and A⊕B. Outputs A and B are in quadrature, meaning they are 90 degrees out of phase. Output A⊕B is the exclusive OR of the two channels, which doubles the standard resolution of the encoder. The outputs, 0 to 5 digital volt pulses, can drive TTL loads.

The Michigan Scientific EC-LV Encoder Signal Conditioner converts the 0 to 5 digital volt pulses of the WPT sensor encoder to linear voltages proportional to angular position and angular velocity. The EC-LV can be added in-line with the stator cable and does not require and additional programing. The external switches allow the user to select the range of speed and the direction of rotation.

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.