About Data Acquisition
A data acquisition system measures and records important vehicle parameters via sensors. These parameters can be analysed to gain insight into the behaviour of the engine, chassis and driver, which can ultimately result in greater predictability and better performance on race day. Over recent years, data acquisition systems have become powerful tools that are vital to success at all levels of motorsport.
The basic hardware requirements include a logging device, sensors and wiring, plus a PC for data download and analysis. MoTeC's Dash Manager software program is used to configure the logging device.
Various sensors can be used to measure vital parameters of the engine and chassis. For example:
- Wheel speeds
- Lateral and longitudinal acceleration
- Tyre temperatures
- Brake pressures
- Engine speed (RPM)
- Engine temperature
- Oil pressure
Driver input can also be measured. For example:
- Throttle position
- Braking force
- Steering angle
The sensors are wired up to send measurements to the data acquisition device, which logs this information for later analysis and also uses it for immediate functions. For example, sensor measurements can trigger programmed alarms (e.g. low oil pressure) and may be used to calculate relevant values like lap times, ground speed and wheel slip.
Selected data can be displayed to the driver on a digital dash in the cockpit. Most commonly this includes lap time information and vital engine details, in combination with shift lights and warning lights. MoTeC often integrates the display and logger in one Dash Logger unit.
The data recorded into the logging device is downloaded to a PC, either each time the vehicle comes into the pits or at the end of a race, rally, drag run or test session. The available memory varies greatly from system to system and more recent logging devices use USB or Ethernet communication for fast download.
The frequency of each logging sample will depend on the parameter being measured. For example, engine coolant temperature changes slowly so it needs to be logged every second, whereas engine RPM or wheel speed changes very quickly and need to be logged at 20–50 Hz (20–50 times per second). If the coolant temperature is logged at 20 Hz it will waste logging memory; and if RPM is logged at only 1 Hz it will not be useful as a lot of detail is missing.
Logging resolution is another key variable in data acquisition because it can impact the quality of your data. While it’s unnecessary to record engine temperatures in fractions of degrees, it can be very important to have this level of detail when analysing, for example, changes in suspension position. Resolution is a key point of difference when comparing data acquisition brands.
The real strength of data acquisition lies in the analysis of the logged information. See Data Analysis Tools for more on specialised software for analysis and telemetry.
Usage of Data Acquisition
- Monitor the health of the vehicle
Data acquisition can help to improve the reliability of a vehicle and prolong the life of the engine and other components. Potential problems that cannot be spotted with standard gauges may be detected by monitoring the drivetrain on all parts of a track and identifying irregularities. For example:
- A standard oil pressure gauge is heavily damped and does not show short dips and surges. Even if a dip occurs on every corner it may not trigger an alarm, but it will damage the engine in the long run. Data analysis highlights these small changes, ensuring the problem is addressed early and expensive repairs are avoided.
- Telemetry data may show wheel lock-up the driver cannot notice. The team can warn the driver and prevent early tyre failure.
- Improve driver technique
- Driver inputs such as throttle position and brake points can be monitored against a reference lap. The resulting sector times can be analysed for the effectiveness of a driver's style in comparison with other drivers or with previous data from the same driver.
- The use of GPS track mapping allows drivers to overlay and compare driven lines to determine the most effective approach of a particular corner or section of track.
- Eliminate trial and error testing and speed up improvements
When data is logged during testing and analysed on the spot, valuable track time can be used more efficiently. Instead of relying on a hit and miss approach to set up changes, results can be reviewed immediately with quantitative data to confirm or add to driver feedback. For example:
- Oversteer and understeer can be measured at individual corners and used to determine chassis adjustments.
- Adjustments leading to higher straight line speed but lower corner speed might result in equal lap times but analysing the data will provide valuable information for setup on different tracks.
- The engine can be tuned more accurately, using 'on track' Lambda measurements. See Lambda Was feature in MoTeC's ECUs.
- Store data for archiving and retrieval
Data logging can record almost everything that happens during a test or race session. It can be extremely useful to store this information and look back at the data before the next outing at the same track. By doing so, vehicle setup can be faster and more efficient.