Active Mountain Bike Shock
Electronically controlled active and predictive damping system that updates Low-Speed Compression damping based on a predictive terrain model. nRF53 BLE Embedded System with a micro-neural network drives the custom solenoid valve.
Scope & Overview
For this project, I set out to design a custom (monotube IFP) mountain bike shock which takes IMU & Damping Oil Pressure inputs, mapped to an low-energy Bluetooth SoC (nRF53) embedded system with a micro neural network for predictive damping. Due to the limited SoC memory, hard-coded cases will also be coded in (predictive and responsive. i.e. drop detected or rapid oil pressure increase, open damping valve)
At the time of writing, I am currently working on the electronics/Altium PCB design along with mechanical integration.
Initial Design & Prototyping
Before working on the damping circuit & electronics, I wanted to validate a basic 3D-printed shell would fit my mountain bike frame – initial drawing dimensions and 3D-printed prototype shown below.
Electricals & PCB Design
Problem:
The first main issue I’ve run into is that a stepper-motor actuated damping needle will not have the response time I desire (this was my initial plan). I have since pivoted to using a solenoid valve, however, commercially available solenoid valves are either not commercially available, or very expensive.
Solution:
Custom solenoid valve, with magnetostatic simulation to back force calculations. A preliminary model of this has been completed, though all dimensions are currently placeholders – need to perform CFD to validate damping characteristics.
See my Custom Miniature Solenoid Valve
PCB Design – Main Components (I2C interface):
- nRF5340 main low-power SoC with Bluetooth (QFN)
- Chosen over an ESP-32 due to BLE power efficiency
- MS5837-30BA pressure sensor
- Up to 435psi (measures internal floating piston (IFP) nitrogen pressure)
- ICM-42688-P
- 6-axis IMU, +/-16g, 8kHz
Powered by a 1000mAh LiPo, which should provide over 10 hours of battery life. 3 Damping States – Predictive, Open, and Closed.
Integration to Mechanical Design
In the works…
CFD & Thermal Simulation
In the works…
FEA, Housing Stress Testing
In the works…
Software & ML Network
In the works…
BOM, Final Design & Results
In the works…