How Power Steering Ruins Feel & Feedback in Racing
Power steering is often used at a last resort by race engineers to keep their drivers content and under their fatigue limit.
In a fully sorted car with a standard steering wheel, the primary steering force comes from the friction between the gloved hand and the wheel.
Resorting to power steering is the last resort after optimizing the coefficient of friction at the human-machine interface (~0.33).
When drivers keep smaller muscles located furthest from the body's core in their proprioceptive sweetspot, the brain has greater resolution in reading the steering resistance feedback signal.
The limit suddenly seems to light up in the driver's mind with a relaxed grip compared to when you had to squeeze the steering wheel in order to impart a turning force.
Designing steering wheel grips to account for the lower steering resistance of power steering means taking advantage of the extra sensitivity that lies between the fingers. Since callouses are normally not present in this area, improperly designed steering wheel grips have a pronounced negative effect.
Conversely, PROPERLY designed power steering wheel grips can enormously enhance steering feel. So, extra care is needed when designing steering wheels grips for power steering systems.
Since the touch is so light, ingress/egress ramps require careful consideration, as well.
Ideally, the best solution is to discard the power steering system entirely, and use a properly designed custom-molded steering wheel that has all muscles operating at their sweetspots with drivers deep in the loop.