Customer Solutions

NI LabVIEW Speeds On-Track Decision Making and Shock Absorber Development

Author(s):

Gavin Jones, iSport International

Industry:

Automotive

Product:

LabVIEW

The Challenge:

Maximizing on-track test time by monitoring, in real time, data collected from a race car's on-board data acquisition (DAQ) system and accurately and efficiently adjusting shock absorbers for the race car.

The Solution:

Developing a LabVIEW application that acquires and helps analyze race driver inputs, and a VI that simulates forces created by a shock absorber at different settings.

iSport International uses LabVIEW to collect data for shock absorber testing in preparating for European Grand Prix racing.

Our company, iSport International Ltd., races cars in the GP2 series, the feeder sport for Formula One. Because GP2 races at all European Grand Prix as the primary support race, our on-track testing time is very limited. In order to quickly set up cars for the races, we must maximize the use of data we collect from the cars’ on-board DAQ system. There is also a big advantage in correctly calibrating the internal valving and external settings of the cars' shock absorbers from the start. If we can properly test shock absorber settings prior to actual development, we can boost the race car's grip without time-consuming stripping and rebuilding.

We chose LabVIEW 8.20 because it enabled us to quickly create a software solution to meet these challenges. The race driver input application and damper simulation application saved the team valuable time by allowing us to address problems faster. More importantly, they allowed us to be more competitive at the race track.

Race Driver Input Application          

The first solution helps us visualize what a driver is doing in real time. Although the car's on-board DAQ system graphs driver input data – such as throttle, steering, braking, gear, and rpm information – we cannot not always determine, for example, whether a driver is too aggressive on the throttle or brake. We addressed this by developing a VI in LabVIEW to read exported data of relevant channels from the DAQ system in .csv format.

Using a "read spreadsheet" control, the array is split into single streams of data. Speed and lateral acceleration channels are calculated to give a representation of the race circuit shape. The same process is put through a "for loop" using an array size function to read the array and control the loop. A time delay is then factored into the loop equal to the sampling rate of the data (100 Hz). This is entered on an x/y graph of the circuit shape and appears as a dot moving around the circuit in real time. The other channels are put through a "for loop" that is controlled the same way – with slider, dial, and Boolean indicators in it so that the channels all update in real time. When the VI is run, we can see where the indicator dot is on the circuit, and precisely determine throttle, braking, steering, and other variables. We can quickly identify if a driver is too aggressive on the controls, causing a car imbalance, and we can show an inexperienced driver what the circuit from a more experienced team mate looks like.

Damper Simulation Application 

Because shock absorber stripping and rebuilding is time-consuming, we developed a VI in LabVIEW to simulate the forces that various internal and external valve settings produce. This allows us to try a combination of possible settings in a few seconds, enabling quick decisions about internal specifications.

To get the raw force values, we run various internal specifications on our damper dynamometer with all adjusters set at their minimum value. We then test the effect of seven different damper speeds, gradually stiffening the adjusters. These raw values are entered in spreadsheets and are the starting point for the damper simulation VI. On the front panel of the VI, there are two "open file" controls – one for bump values and one for rebound – that allow us to select one of the spreadsheets. Next, we pick settings for the adjusters using enumerated controls. These are controllers for various case structures in the diagram. They add different multipliers to the base force, depending on the settings chosen, and are then displayed on an x/y graph as the datum array.

There are links to these controls in a mirror image of the damper simulation VI, which is in a "while loop." This keeps the VI running and allows us to make adjustments to the virtual damper and display the adjustments on the x/y graph over the static datum array. String controls read the adjuster information and display the settings on the front panel of the damper simulation VI in a string indicator. This enables us to keep track of settings as we change them. Finally, there is a Boolean button to stop the while loop and VI when we finish our analysis.

For more info contact:

Gavin Jones

Tel: 0044 (0)1953 788878

Fax: 0044 (0)1953 789978

E-mail:gavin@isportinternational.com