P07307: Controls for Dynamic Suspension Mark Lifson Project Manager Todd Simon Technical Lead Kapil Chandersen Engineer Khue Ho Engineer Sponsor: After Hour Racing LLC

P07307: Design Concept Shock position Coil-over spring MR shock replacing the mechanically adjustable shock Rear right tire

P07307: Overall Design Power Filtering Circuit Current Amplifying circuitry MCU Accelerometers Yaw rate sensor

P07307: Project Description Developed a Dynamic Suspension System - controls the damping co-efficient on a sprint race car - responds to significant track conditions e.g. banking degree, corner radii, roughness etc. - suspension system controlled through adjustment of rear right shock - uses magneto rheological fluid to dynamically adjust the damping co- efficient - sensors consist of 2 accelerometers- mounted: center of gravity & front right wheel, 1 yaw rate sensor Gives a better control over the sprint car and hence win races Key high level customer needs / engineering specs: - Basic Requirements: Max value for current of approx. 1A Response time ≈ 25ms Power consumption < 50 watts System weight < 20lbs - General Dynamics: System valving requirements for regular shocks (1-6) System uses valving rating of 3-5 for regular shocks Max. damping co-efficient ≈ 240 lbs@ 8in/sec Min. damping co-efficient ≈ 50 lbs@ 8in/sec

P07307: Technical Risk Assessment Risks: Ability to accurately sense turns Ability to sense bumps with front, right wheel Determination of shock response time Possible system lockup Mitigations: Added yaw rate sensor to detect turns Determined response time through shock dyno or in the final implementation on the car Added software logic to return shock to “safe” state and LED indicator

P07307: Current State of Design Robust Design Design is feasible and meets customer requirements Would require technical expertise for system modification (software) Design meets all engineering specifications for the full system except: Unable to validate response time Current Limiting Circuit may have Linearity/Stability Issues Available project budget is $1000 Project BOM budget: $538 Miscellaneous: $170 PCB costs: $155 Remaining Balance: $136

P07307: Budget Distribution

P07307: Future Enhancements Improve operator interface (add functionality) Look into tensile testing of the shock to determine better sampling rate and shock response time Look into Mechanical Bench testing Improvement of PCB layout Addition of further functionality: More complex control algorithms Multiple, independent shocks