Four On The Floor: All-Wheel-Drive Dynamometer Test

Online Editor

Juliet Elliot uncovers the benefits of electric vehicle development testing on an all-wheel-drive dynamometer
In recent months Volvo, Ford (Europe), Jaguar, Mini and Bentley have announced ambitions to become pure battery electric vehicle (BEV) brands by 2030. Other brands have followed by announcing that BEVs will be their major production volume by then.

Some automotive analysts have predicted that the tipping point for price equivalence between ICE vehicles and BEVs is likely to happen some three years earlier, in 2027. The EU is discussing whether to increase the (already ambitious) target of 37.5% CO2 reduction to an even higher 55% reduction. This naturally puts pressure on all OEMs to embrace alternative propulsion systems to combustion engines – such as electrification.

While transferring from one propulsion source to another may seem a simple task, it can cause issues for the existing vehicle development and testing infrastructure. With a completely new powertrain, new aspects of testing must be considered, as well as the efficiency in such testing. This, as time-to-market is critical when the rate of market adoption is so high. An indication of this is Tesla’s recent valuation that exceeds five of the major automotive OEMs combined.

Testing the Powertrain

With ever-tighter development cycles it is no longer viable for OEMs to postpone a road-testing session by six months due to weather and road conditions not being ideal for the test in question. One solution is, of course, to find a location on the globe where the road conditions are more suitable – in most cases, this is a very expensive and resource-intensive choice.

Swedish company Rototest has been working in the powertrain testing field for more than three decades. Its main activity is the provision of hub-coupled powertrain dynamometers, supporting OEMs and Tier 1s as they increase development efficiency and reduce costs. For instance, moving powertrain calibration into the lab (road-to-lab), makes huge cost and time savings as the testing environment becomes more stable, with increased repeatability a key result.

The Rototest powertrain dynamometer boasts innovative features such as a floating mounting solution that does not require anything more than a hard floor to be installed. As there are no horizontal forces acting on the vehicle during testing, monitoring full acceleration or emergency braking is simple, and a stable testing environment is ensured together with an unmatched installation time.

The dynamometer system uses sophisticated algorithms in its control system to enable the vehicle to experience realistic road conditions, all without the hassle of a complicated user interface. The vehicle can be installed in the all-wheel-drive dynamometer system and set-up ready for test in less than 20 minutes using ordinary automotive workshop tools. For customers requiring a high throughput rate, the time can be reduced to 10 minutes (with production flow options).

The floating mounting solution also enables automatically adjustable wheelbase and track width, even during vehicle operation, as well as automatically adjustable camber angles and wheel angles such as toe-in. Unnatural stresses on suspension components such as wheel bearings or suspension bushings are avoided with this design.

Another benefit of the floating solution is the capability of physical steering, i.e. the vehicle may use its steering during testing – a crucial feature for certain advanced driver assistance system (ADAS) functions as well as automated/autonomous driving (AD) testing.

ADAS functionality is a broad term that includes a multitude of different technologies and vehicle subsystems. Functionality includes ACC (adaptive cruise control), LKA (lane keep assist), automated parking and other functions that are continuously added with a growth rate that is rapidly increasing as new sensors and technologies become available.

The ADAS integrates multiple sensors and control systems to control the vehicle. A system commonly includes sensors such as radars and cameras integrated with several electronic control modules for powertrain, brakes and steering.

ADAS testing and calibration consumes a substantial proportion of the overall testing and calibration time of a modern vehicle. Rototest’s customers report time savings of up to 80% by moving calibration manoeuvres from road testing into the lab. The modular structure helps here. Regardless of whether the ADAS function can use the road-correlated, time-saving and integrated vehicle model or requires a higher-fidelity model for complex scenarios, both use cases are fully supported and deliver a cost- and resource-optimised testing environment.

Being a specialist in the field of hub-coupled dynamometers, the company cooperates with partners globally to build fully integrated solutions where the dynamometer system acts as a subsystem together with other systems such as emissions, visualisation, simulators, chambers, measurement and automation systems.

Rototest builds its solutions with two primary users in mind. Firstly, the engineer who is completely focused on a specific test scheme or manoeuvre and wishes to conduct it in the most time-optimised manner without desiring to find a dedicated test site. For this engineer, Rototest offers standardised test modules that take minutes to set up even though the actual test may involve complex modelling.

The other user is the engineer who is keen to be in complete control and wishes to use pre-existing vehicle models, or simulation equipment that is not yet physically available, such as sensors or propulsion systems (hardware-in-the-loop, HiL). To satisfy this, Rototest’s dynamometer systems offer full transparency in running external controllers such as in vehicle-in-the-loop (ViL) scenarios. The same standardised system supports both applications equally.

Juliet Elliot is with Rototest

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