Data acquisition system

From Wikipedia, the free encyclopedia

Data logging, carried out by a data acquisition system (DAS), is used to measure parameters such as temperature and humidity in storage facilities with perishable products; the measurement data is then stored for analysis to improve quality assurance.

[edit] Data Logging Systems

Data logging systems consist of four elements:

1. Measuring output (sensors around the vehicle)
2. Recording output signals (logger unit)
3. Uploading/accessing recorded data (telemetry)
4. Analysis of recorded data. (DAS software)

The 4 elements above have specific requirements which need to physically present and included in the design process. Sensors to measure selected parameters must meet certain specifications, and the routing of the sensor cables ensures they will not suffer from electromagnetic interference from other electronic systems. The DAS unit (including memory) and the link from the DAS unit to the operating platform to upload the acquired data via a hardwire cable or telemetry also must conform to requirements.

Most race cars use two types of telemetry. The first is sent to the engineers in the pits every time the vehicle acquires more than 50Mb of data, containing an insight into the state of the vehicle. The second is transferred each time the vehicle is in the pit lane, providing information on every part of the vehicle. With the most advanced telemetry, the data is sent constantly for analysis through a transmitter as long as a good connection is present (not always possible in parts of certain raceways due to obstruction).

The operating platform is required to include specialist analysis software to view the data, usually in the form of various graphs to improve and develop the performance of the key areas and operation parameters of the vehicles running conditions. The most advanced software in Formula 1 has been developed by McLaren Electronics known as Advanced Telemetry Linked Acquisition System, which displays graphs of each of the vehicle's systems on the exact section of track, in a real time format. The benefits of using such a system include the fact that the parameters which can be recorded for analysis cover the whole set-up of the race vehicle (up to 127 channels).

The parameters which are measured and recorded by a data acquisition system are broken into three generic categories, which are also interlinked due to system requirements and the complexity of major components (for example, a wheel speed sensor not only monitors the wheel speed but also the speed of the vehicle, location on the track and an input to traction and launch control systems):

1. Engine: Revs per minute, fuel and oil pressure, water and oil temperature, turbo charger boost pressure, exhaust gas temperature, battery voltage, inlet air temperature and throttle position sensor.
2. Chassis: Wheel speed, steering angle, lateral and longitudinal G-force (applied from braking and cornering), Brake line pressure, damper movement and gear position.
   • Advanced Chassis DAS: Ride height, drive shaft or prop shaft torque, suspension loads, tyre pressure and compound temperature, and brake disk temperature. Optional: aerodynamic parameters, including air speed and local air pressures.
3. Driver: Both engine and chassis-related factors which are controlled by the driver, such as throttle position, gear position, steering angle and brake line pressure or directly controlled parameters such as engine revs per minute, speed and G-force.

The accurate information provided by telemetry sent by DAS in a practice run takes significant fine tuning, such as ensuring the correct gear ratios are present according to track layout, or that the engine acceleration speed according to throttle position and sensitivity is set to the required conditions of a race. The engine control system will be programmed with suitable engine maps giving the driver more control of the throttle input. On a track with a large number of corners, the first part of pedal movement would be made very sensitive in order to effectively negotiate the course. On other courses, however, the vehicle might be required to come out of the chicanes and directly to peak power levels, thus less sensitivity required on the pedal.

The DAS during race time is monitored by engineers in the pit and garage area, who diagnose any faults which may occur. In this case, the DAS is used as an early warning system of potential mechanical failure, allowing the designers and material analysis team to easily distinguish the cause of the fault. This can result in a significant decrease of the danger to a driver.

A good example of this can be taken from the 2003 Silverstone Grand Prix, when engineers in the pits observed the loss of pressure from one of Coulthards tyres. The DAS allowed the team to recall him from his practice, resolving the fault before a dangerous situation occurred.

“Formula 1 telemetry is the technological lifeblood of the sport, helping the drivers and engineers to better understand how a car functions and how they can optimise its set-up.”^{[citation needed]}