Developing a Mobile Climatic Chassis Dynamometer Controlled by LabVIEW

Bertrand MARREAU, Maxime MULLER, V-Motech

"The modularity offered by this type of reconfigurable hardware to program the FPGA and the presence of a real-time OS made it the perfect solution for prototyping the bench and being rapidly available for production."

- Bertrand MARREAU, Maxime MULLER, V-Motech

The Challenge:

Implementing the driving system of a climatic chassis dynamometer, which is mobile and was developed in a trailer so space is limited, within a strict budget.

The Solution:

Using the CompactRIO platform to develop the entire driving system, all controlled by LabVIEW software.

The modularity provided by a reconfigurable hardware to program the FPGA and a real-time OS made it the perfect solution for prototyping the bench and made it available for early production.

V-Motech, based at Longjumeaux near Paris, is an innovative start-up in powertrain testing for R&D activities in the automotive sector. The company provides equipment manufacturers and automakers the first Mobile Climatic Chassis Dynamometer (V-Road). The team in charge of electrical and electronic systems aims to realize the test driving system, for both hardware and software.

Climatic Environment of -35 °C to +60 °C

V-Road is a test bed for a climatic dynamometer, which is used in the automotive industry to test and is designed to comply with quality, performance, and pollution objectives through fine tuning of the vehicles. The purpose of this method is to have an optimized tire contact/rolls with a power of 200 kW, a force to the wheel of 9,800 N, a simulated inertia class from 700 to 3000 kg, in a climatic environment of -35 °C to +60 °C, all within a regulatory ±2 °C, roll speed-sensitive ventilation grille, driving guide, data acquisition of bench, and vehicle information.

Spatial and Temporal Constraints

We developed this bench in a semitrailer with limited space for the driving system. A system like CompactRIO has the advantage of taking up less space than a PXI system or a PC with a real-time OS.

We used NI hardware to obtain a working prototype under extremely tight deadlines and quickly provide an operational test means for production. In addition, the NI ecosystem achieved very satisfactory results in a very short time, thanks to LabVIEW software and the reconfigurable and scalable CompactRIO.

For the driving part, we used the LabVIEW software with the HMI framework, which provided us with a healthy and scalable base structure. Finally, programming the real-time part has been greatly facilitated by the use of time loops and variable global functions for data communication.

A Wide Range of Modules

The hardware solution consists of cRIO-9074 controller for control and monitoring the entire bench. The modularity offered by this type of reconfigurable hardware to program the FPGA and the presence of a real-time OS made it the perfect solution for prototyping the bench and being rapidly available for production.

We added several modules to the CompactRIO chassis, including two common I/O modules, in order to acquire dynamic signals (such as digital encoder and torque) and to drive the power relays. We also used a 24 V digital input module (NI 9425) to get a return status of the various bench contactors driving the power devices (variators, evaporators, and more).

Furthermore, to control the cold temperature, we used an RTD input module (NI 9219) for accurate temperature acquisition throughout the climate control loop. To acquire less essential temperature data, we used a simple NI 9213 thermocouple input module also. The large number of channels per module means we can place many thermocouples at different locations on the test bench or test cell.

The presence of certified developers helped to architect the project according to the best practices, so we could obtain a scalable and sustainable software structure.

Additionally, the collaboration and assistance from the technical support team and sales engineers at NI helped us correctly define the hardware to use and provided guidance on its implementation.

Reduced Development Time

Using LabVIEW and CompactRIO has reduced the time needed to provide a working system. We completed development of the final solution—currently in production—within a few weeks.

We are now looking for ways to improve the driving system by adding more channels for measurements and by deploying more measurement accurate data acquisition systems.