Post by Moaz Mohammed

Continuing my FSUK22 MATLAB Simulink Vehicle Dynamics series — Posts 1 ~4 on my profile. Today we are talking about braking system sizing. Most brake system components are off-the-shelf. The challenge is selecting the right ones for your specific vehicle. The parts we designed in our system are the brake rotors, pedal box assembly, and pipelines. Everything else — master cylinders and brake calipers — is sourced. The tricky part? Sourcing these in the Egyptian market. We don't have accessibility to motorsport-specific components. But you'd be surprised what works perfectly for Formula Student vehicles. What actually works — and what I learned the hard way: - Brake Calipers: Look at superbike front brake systems. These bikes have very high top speeds, and the front typically runs two calipers per wheel. The piston count on each caliper is well-suited for Formula Student brake efficiency. What's also great — superbike front calipers are mirrored pairs, meaning the bleeding valve sits on top on both sides. That matters during assembly: you don't have to invert the caliper on the left wheel to get the bleeder in the right position. - Rear calipers from superbikes are usually single units. They work perfectly — but you will need to invert one of them due to the bleeding valve position. I learned that the hard way. 😅 - Master Cylinders: These can be found on pickup trucks. But here's the interesting part — it's not the brake master cylinder you need. It's the clutch master cylinder. (It has single output port, you need two) How the model helps: I'm not going to explain how brakes work from first principles — let's focus on what the model actually does. The main target is wheel lock detection. After selecting your off-the-shelf components, the model checks whether the system can actually lock the wheels. In real life, brakes can operate and completely fail to lock a wheel — that's insufficient hydraulic pressure, and it means your braking distance is nowhere near optimal. I added a human input signal to mimic the behavior of a driver pressing the pedal — a ramp input reaching full pedal force at ~1.3 seconds, then holding. The model then simulates the full braking event. What the graphs show: - Under braking, weight transfers forward — front dynamic load increases, rear decreases. You can watch this happen in real time in the simulation. - When braking force exceeds the dynamic wheel load, the wheel locks. The rumbles visible in the graph around t=0.7s are exactly that — lock, release, lock again. - Stopping distance: ~17.5m from 40 km/h in ~2.1 seconds. That's a number you can take straight to the driver and the scrutineers. From here I can tweak the bias bar value to adjust the front/rear wheel lock timing, and the model gives me the design parameters for (rotor diameter, pedal ratio, and bias bar setup) — all in one run. #MATLAB #Simulink #FormulaStudent #VehicleDynamics #BrakeSystem #MathWorks #FSUK #RacingEngineering #AutomotiveEngineering