Building a Testbench to Validate Anti-Lock Braking Systems on E-Bikes
Approach Has Potential Applications in Automotive and Construction Industries
“We initially thought it would be a challenge to interface Speedgoat with Simulink because we had never done that before. However, it was much easier than expected thanks to the available interface libraries and the documentation from both MathWorks and Speedgoat.”
Key Outcomes
- An HIL testbench allowed for safe, reliable, and reproducible validation of ABSs on e-bikes in a laboratory setting, mitigating the risks associated with hard braking in on-road testing
- A fully customizable bike model can adapt to any type of e-bike or weight distribution, while also making it possible to integrate existing ABS systems from different manufacturers
- The HES-SO team developed expertise that can be applied to the automotive and construction machinery sectors
An HIL testbench setup (top) along with validation results (bottom).
E-bikes are increasingly gaining popularity for a variety of personal and business applications. Safety is an important concern for these vehicles, so the e-bike industry has begun to adopt anti-lock braking system (ABS) technology. However, testing ABSs on e-bikes is difficult—especially in the initial stages of road validation—as hard braking with front wheel lock poses a risk to the rider.
To overcome this challenge, Professor Emmanuel Viennet from the Fribourg School of Engineering (HES-SO Fribourg) in Switzerland decided to build a hardware-in-the-loop (HIL) testbench that enables safe, reliable, and reproducible validation of ABS on e-bikes in a lab. Professor Viennet’s team created a Simulink® plant model of an e-bike by writing the equations from scratch. Parameters for force transmission to the brake calipers, coefficient of friction between brake discs and pads, and suspension behavior were identified from measurements conducted on a real bike with a deactivated ABS. The team found that the simulated front wheel speed, deceleration, and longitudinal acceleration closely matched the results obtained from the real bike. From this validated Simulink model, code was then generated and downloaded to a Speedgoat® real-time machine, itself interfaced with the ABS hardware.
The physical testbench includes handlebars with a hydraulic front brake lever operated by a pneumatic cylinder. A sensor detects the force at the brake caliper, serving as the sole input to the virtual e-bike. A phonic wheel, powered by an electric motor and a signal from the real-time model, simulates the front wheel rotation to generate the speed sensor signal for the ABS. Additionally, the real-time model simulates the embedded inertial measurement unit by computing the e-bike acceleration and transmitting it to the ABS hardware via a CAN message using the Speedgoat I/O driver library.
The bike model is fully customizable, allowing it to be adapted to any type of e-bike or weight distribution. It can be integrated with existing ABS systems from different suppliers and allows test automation. E-bike builders and ABS manufacturers can use it to quickly validate performance in a quantitative, safe, and reproducible way for numerous test cases. The expertise gained by the HES-SO team is intended for use in future development projects within the automotive and construction machinery industries.
