The ever increasing number of global vehicle platforms is pushing OEMs to develop and validate a growing amount of variants: although global in a sense, each platform must satisfy diverse regional requirements, and be tweaked to suit local specifications. At the same time, it is getting more and more difficult for manufacturers to get systems integration right the first time.
The potential for simulation to replace hard prototypes has been debated for many years, with the boundaries being rolled back as increasingly sophisticated software and faster hardware continually make new applications feasible. The most tangible aspect of this trend has been the increasing use of vehicle simulators which allow engineers to experience a vehicle virtually, long before a prototype exists.
Unfortunately, meaningful simulation of a vehicle’s dynamic properties has been held back by the evolutionary route taken by the simulator industry, says Chris Hoyle,Technical Director of UK specialist software company rFactor Pro. “Simulator platforms have their origins in the aerospace industry,” he comments.“However, the rate of turn of even a modest family car in an emergency manoeuvre is much faster than a fighter aircraft. To provide effective Driver-in-the-Loop simulation, we need a different approach with greater emphasis on the speed of response.” [quote align=”right”]By supplementing engineering data with subjective ‘feel’ in the early concept stages of a new vehicle programme, years before real vehicle hardware is available to test, better decision making becomes possible
Most simulators are effective for low bandwidth, low frequency applications such as man-machine-interface development and human factors studies, but their high mass and poor latency (the time taken to close the feedback loop) – often exceeding 100 milliseconds – limits the range of application. To provide realistic simulation of vehicle handling, dynamic safety systems and other high performance activities requires latency of less than 50 milliseconds, with high bandwidth communication between the vehicle model and the road surface model.
The leading vehicle modelling tools used to study vehicle dynamics are already at the necessary level to allow Driver-in-the-Loop simulation. But the missing links have been suitable high-bandwidth software to close the loop quickly enough through the driver, and motion platforms with lower inertia to provide quicker responses.
Using lessons learnt in the highest levels of international motorsport, the latest generation of motion platforms are significantly more dynamic, assisted by off- platform mounting of the entire vision system. The new approach, complemented by recent advances in software that speed up the visual, aural and other cues to the driver, could usher in an era of unprecedented progress towards the full simulation of vehicle dynamics.
“The potential benefits for the automotive industry greatly outnumber those for motorsport teams,” explains Hoyle. “By supplementing engineering data with subjective ‘feel’ in the early concept stages of a new vehicle programme, years before real vehicle hardware is available to test, better decision making becomes possible, avoiding costly revisions later.”
The complex interactions between dynamic systems, such as passive chassis behaviour, electronic stability control and driver workload management can be studied more effectively, in complete safety, with a level of repeatability not possible in ‘real world’ testing. For example, the evaluation of SUV roll-over stability would be transformed by the freedom to repeat limit manoeuvres, time after time, without variations in tyre grip, cross wind and other conditions.
“Such is the fidelity now available, even the cabin NVH levels of alternative driveline mountings can be evaluated or the effect, on handling, of long term deterioration of suspension bushes,” added Hoyle. “Imagine the improvement in major purchasing decisions made possible by virtual testing of the alternative technologies from competing suppliers, early in the concept stage of a new vehicle programme.The benefits of different solutions could be compared and ranked prior to any hardware investment, allowing a more optimal selection to be made, based on much higher confidence levels.”
Aaron K. Warner
This article was first published in the Q4 issue of Megatrends magazine, to continue reading, simply download your free copy now.
