Strut suspension analysis - this is eye opening

[Elombard]

The fourth-gen BMW M5 sedan's suspension test rig is mesmerizing | Autoweek

Look at this short video of BMW M5 suspension development on a test rig.

Its very interesting to see the camber changes in a strut suspension as they load it in different scenarios.

Its always been kind of hard for me to visualize some of the geometry changes that suspension technicians talk about when building better suspensions for performance.

Also interested to hear what other folks spot - I think there is lots we can learn!

[chris_seven]

https://www.youtube.com/watch?v=ySL3_f0cWcw

My company used to design and manufacture a range of servo-hydraulic damper test, 4 post and 7 post test rigs for the F1 industry.

The first system we supplied was to Benneton back in the Active Suspension era and supplied then Arrows, Ligier, Lotus and Ferrari as will as Citroen for their Paris Dakar programme.

We could input road/load data from different circuits and vary downforce to model aerodynamic changes.

The vehicle tended to be fully instrumented and we had around 160 channels of data logging.

The final systems we manufactured used 32 bit digital controllers and were quite well developed.

I was in charge of Sales and Marketing and we sold this business in around 1998 and moved on to other engineering work. I am sure that these types of system and now much more commonplace and much more developed.

They really are an invaluable tool.

[Elombard]

Wow thats amazing - the active suspension era was very fantasy inspiring for me. I was star struck by the technology.

SOme of the speculation about the technology that I read was mind blowing.

For instance - do you know if the teams had the tracks mapped to cm level or something and the car knew where it was and the suspension would anticipate the turns and bumps and adjust BEFORE they actually encountered the turn or bump?

[chris_seven]

Originally Posted by Elombard

Wow thats amazing - the active suspension era was very fantasy inspiring for me. I was star struck by the technology.

SOme of the speculation about the technology that I read was mind blowing.

For instance - do you know if the teams had the tracks mapped to cm level or something and the car knew where it was and the suspension would anticipate the turns and bumps and adjust BEFORE they actually encountered the turn or bump?

The classic example was when Schmacher hit the wall at Spa on exiting the pits.

There used to be a bump in the track on the pit exit and the car bottomed.

The track was fully mapped into the car but there was a 'creeping' error with respect to distance so the 'map' was reset to a known track position from a transponder at the end of the straight.

The Benneton used to lower its rear ride height on the long straight to help the aero system and when it reset the car raised back to the ride height that took it over the bump.

When the car went into the pits it missed the transponder signal and needed a manual reset from the driver - a simple press button.

When the driver didn't remember to press the reset as he left the pits the ride remained lowered, the car bottomed over the bump and bounced into the wall. - Race Over.

We used to design digital servo controllers and operate MOOG valves as part of our business and as we also made very low friction actuators so we had a good input into active systems.

Our basic controllers used to provide a 1:50 000 position control resolution and had a PID control loop update rate of 100 microseconds. - Quite fast at the time.

When traction control was banned 'throttle position' mapping became an interesting technique.

We designed and manufactured a torquemeter that fitted in the engine of an F1 V10 and provided data to the on board controller and this gave an enhanced performance compared to a simple throttle position map.

We also developed a gearbox test rig that decelerated the input shaft of the gearbox of a F1 car from 20 000 rpm at full load at a rate of 240 000 rpm per second which was the decal rate of a V10 Renault motor when the spark is turned out.

The objective was to change gear at dog to dog speeds to 2000rpm to maximise acceleration and minimise gear shift time.

The rig we developed was driven by hydraulic motors and was very successful being used for launch and gear shift on the Renault Alonso used to win his world championships.

We also fitted torquemeters into the drive system of the Ford Focus WRC car which were used for drive system and traction management.

Fun times.

[steely]

Amazing test setup - I had no idea.
My comments are directed more on the test config rather than suspension design.
The test conig/system is incredible, like test engineer porn.
I'm a retired eng'r, and for most of my career I worked in aerospace test. We always strove for realism (but had to work within a budget so sometimes we had to get creative with fixturing).

[chris_seven]

We used to make a few Aircraft Test Systems - this is a C130 Wing Test - Tip to Tip it also has inputs to simulate torque from the engines and a trick 'lock up and let down capability.
It has run in excess of 30 000 hours without breaking the 'test specimen.
The system is now maintained by a third party as my old company's new owners relocated the business to Germany.

My last real engineering project was involved in producing the 'Iron Bird' for the F35.

[Canada Kev]

That BMW video is pretty eye opening. Really show what kind of abuse tires endure...