How fast is GPSCAN 100Hz?

As of 1.1.2025, 100Hz devices are replaced with GPSCAN MK2 50Hz. See the performance difference here

 

Below is an example from one customer who uses 100Hz GPSCAN to control the traction of the vehicle. Vehicle has 2 wheels, about 700hp going to the rear wheel.

Vehicle uses Haltech ECU and GPSCAN gives the speed to the ECU via a digital input using GPS Pulse output. GPSCAN simply emulates a typical Hall sensor. This digital input is then set as the source for the front wheel speed channel.

Rear wheel speed is taken from a real Hall sensor installed to the rear wheel.

These inputs are then used by the ECU to calculate the wheel slip % and control the power output of the engine.

Data

Below are some graphs from the data (Both channels logged @ 200Hz by the ECU):

  • Blue: Rear wheel speed from real Hall sensor
  • Orange: GPSCAN 100Hz GPS Speed
Complete run

Blue trace has a spike and is a point where the rear wheel starts spinning and looses the traction. This is where Traction control comes into the picture: Power of the engine is reduced and spinning stops.

Lost traction zoom

Closer look at the launch: There is a small difference between wheel speed and GPSCAN Speed. Reason is that tire deforms during the launch and the wheel also slips a little. Slipping is good, up to a point (Extremum), to accelerate fast. It is important to remember that there is no traction without some slip...

Back to the original question, what is the latency of the GPSCAN 100Hz?

2% slip, latency 10ms

To find the latency, we need to find an area with the least amount of slip. Highlighted area is from the beginning of the launch where the speed is 20kmh and slip is 2%. Highlighted area is 10ms long and the the speeds are equal after 10ms. So, we can estimate that the delay is about 10ms.

This is more than fast enough to control the traction. For example, the slip event in this example lasted 200ms.

This system has been used for 2 years with good results. Performance is consistent and is not affected by installation problems which is typical to devices equipped with acceleration sensors or gyros.

Same method can be used with any ECU that has traction control and supports hall type wheel speed sensors. VR type sensors are not supported.

Large size pictures just in case..

More details about GPSCAN 100Hz

Contact us if you want to do something similar and try it out.

Graphs made by using GEMS GDA Pro (Link to GEMS Downloads page)