To ensure drivers can consistently extract performance from the car through an entire endurance event, that drivers from the 5th percentile female to the 95th percentile male can reach and operate every control reliably, and that the environment is comfortable, informative and free of distraction.
Driver Interface is the parent grouping for Ergonomics, Pedals and Steering. It carries no costed parts of its own; every physical item lives in one of its three child subsystems. Its function is the requirement set those three are designed against, and the integration between them: where the seat puts the hips determines where the pedals must sit, which determines steering position and angle, which determines dash placement and visibility.
Ergonomics is measured, not argued. The team ran a senior design ergonomics jig with participants from the 7th percentile female to the 99th percentile male to establish position ranges and optima, then built an anthropometric percy sketch from the actual driver pool, then used electromyography to measure muscle fatigue before and after endurance stints both on track and in the simulator. Where design limits force a deviation from the ergonomic optimum, the deviation is stated and then tested rather than hidden. CR26I steering angle sits at 18.60 deg against an optimum of 2.93 deg; further testing found it still functional and comfortable, and that is recorded. 1. Establish position ranges and optima from the ergonomics study (12-person sample) for brake pedal, throttle pedal, steering position, steering height, steering angle and thigh angle. 2. Build the percy sketch from current driver measurements and check the cockpit sketch against the frame. 3. Design the seat insert, pedal box and steering geometry to land inside the ranges. 4. Validate with EMG on key muscle groups: maximum voluntary contraction baseline, then an endurance stint, then re-measure. A drop in mean frequency means more fatigue. 5. Confirm egress and visibility, then iterate with driver feedback from the simulator before committing.
- Drivers consistently fast through a full endurance stint. CR26I lap deltas fell to a largest delta of 8.7 s after the seat insert and interface changes. - All controls reachable and operable across the driver percentile range. - Egress in under 5 seconds. - No snag points, no sharp edges, shielded rotating and hot components. - Reduce measured muscle fatigue. Preferred ergonomics showed a smaller baseline-to-post-stint frequency shift than previous ergonomics on both the left forearm and the right quad.
- Steering wheel to dash distance, called out as an improvement in the anthropometric study. - Seat insert support for the lower back, hips, upper lats and side-to-rear delts. - Visibility for the 25th percentile male and 85th percentile female heights, and Bosch DDU-11 to wheel visibility. Addressed on CR26I with an acrylic cutout in the steering wheel shell. - Button placement.
Senior design ergonomics jig. Delsys EMGworks for electromyography, post-processed in MATLAB with an FFT and band pass filters. The driver simulator for repeatable endurance stints. SolidWorks full-car CAD for cockpit sketch and reach checks. Fish scale testing for control forces.