Dynamic Systems in Automotive - NUI Maynooth Network Mathematics Lecture

I was at a lecture in NUI Maynooth today, what follows are my unedited notes (i.e. spelling, grammar, and continuity were not top of the agenda as I scribbled them down) for the first talk.

29/7/2008

Prof Jens Kalkkuhl, Daimler research

TITLE: Selected Topics in Vehicle Dynamics Control

Elements of vehicle dynamics:
vertical: pitch, bounce, roll, warp.
Longitudinal and lateral: yaw motion, longitudunal acceleration, lateral acceleration.
Tyre-road interaction - this is a very non-linear problem. Wheel angle, tyre tilt angle, road conditions(friction, roughness), drive and brake slips.

Wheel loads vary with the vertical dynamics
Road disturbances vary vertical dynamicsa
Tyre forces tie back into long. and lateral dyamics, and vice-versa

Daimler active suspension is called "Active Body Control" - there is an hydraulic actuator in place of a spring for the suspension. Sensors are also required, one that measures acceleration (measures in 4-degrees of freedom), sensor that measures height from tyre to car body. A control unit is also required.

Vertical loads on the wheels are trying to be kept as even as possible in cornering using ABC - this improves the handling of the car.

Disadvantage of active suspesion is it is a closed-loop controller that can only react to something that has happened.

ABC preview has laser scanners equipped, that scans the road, and enables the suspension to be pre-conditioned, so there is nearly zero-body movement - this is cool... I've seen it before though!) "this is one of the most complex control systems you can find in cars these days - in production cars, though not for the next few years"

Kinematics of a moving vehicle - they've got equations in there... can I get a copy of the presentation?

Kamm's circle - there are laws in physics, these I need to know. I can incorporate them into my models, and they will allow me to make assumptions that are safe. - This circle is the basis for why ABS is required. When braking, a smaller angle of turning will lead to skidding, than when not braking.

Steer-by-wire is a 'topic for the future' because it is very complex and can fail. We need to have a mechanical connection between the driver and the wheels still. Driver assistance though will add in a gearing system between the wheels and the steering wheel, this allows for extra or less turning to be added into the driver's amount of turning.

With automatic counter-steering how does the system deal with skilled drivers who also counter-steer?

A simple braking strategy on a per-wheel basis enables good rollover mitigation.

The problem with collision mitigation is that there can not be any false-alarms, and there is a problem with manhole covers, they give a huge radar image, as they are iron. Getting rid of these false images was a difficult problem, the control system was easy. It was image processing that was the problem.

Lateral collision mitigation - driving around a car, this is a decade away, maybe 2 decades. Legal implications? reaction of the other driver? Traffic on other lanes? responsiblity must remain with the driver.

Personal Thought: Are we going to have to start signing EULA's when we buy cars? Waiving rights, saying we assume all responsibilities?

F400 Carving - A complete vehicle dynamics management prototype - D. Ammon et al.

F1 cars have 'stiction' there is so much rubber in the tyres (20-30%) that when they got hot, they literally stick to the ground.

Integrated Chassis control system - done with Daimler and Hamilton Institute in NUI Maynooth- what came out of this project?