Jolle wrote: ↑
Wed Jun 09, 2021 11:53 pm
I believe Lotus had quite a simple but effective active suspension, or more a automatic ride hight/stiffness system. With an increase of pressure of the pilot tube, the suspension was raised, so the car would maintain it’s ride hight at speed, making it possible to run the car lower at low speed. It stil had normal springs and dampeners. The later Williams system was fully controlled by hydraulic actuators (and possibly being the first F1 car with an hydraulic system?)
It was the other way around - the Williams system was a 'slow' active one - basically a hydraulic ram in series with the normal spring so the suspension could and did move without the ram. Perfect for basic ride height control, which in the aero era, was what was wanted without serious expense. Based off what was originally an AP mechanically controlled system.
The Lotus was 'fast' active - no real mechanical springs to speak of, just hydraulic rams simulating spring and damper. Needed a lot more signal processing and response in the hydraulic system to deal with the main suspension and tyre hop frequencies. Way more powerful though. It had proper modal isolation - separate stiffness and damping values in all 4 modes - combined with self-levelling (to any given attitude) and just about anything else you could think of
My first job out of university was playing with both systems (well the AP mechanical rather than Williams) in a very different field of transportation. We ended up playing with variable damping and a lot of system energy reduction stuff - a lot of the time the suspension wants to move under internal forces the way you want it to move, so you just control the movement via ypass rather than trying to drive the ram all the time.
If you search through the Google Patent database, you'll find both systems.
Williams: https://patentimages.storage.googleapis ... 861066.pdf