Hardware

Wednesday, January 29, 2014

Tags :  electronics

It’s all too easy to oversimplify the electronic installation on a modern Formula One car – the ECU usually gains the most attention – but supporting that is a host of other hardware devices, all part of the car’s overall system.

We have covered the ECU in a previous F1-Monitor. The triangular box is often sited inside the cockpit in the ‘V’ below the driver’s legs, while some teams mount it in the sidepod. Being air-cooled, the sidepod location is convenient for cooling and wiring, but being a rather large and moderately heavy device, sidepod mounting requires aerodynamic and centre of gravity compromises.

The ECU is part of a package of devices, the most important being the ignition/injection power box, which provides the outputs for the engine and other electrical systems. Thus the unit is connected to the electrical cut-off switch to isolate the electrics in the event of an accident. The power box also regulates the power supply from the alternator and passes it to the car’s battery. Being connected to the alternator, the power box also provides inputs from the alternator thermocouples and passes them back to the ECU via its CAN bus connection. At some1.5 kg in weight and more than 25 cm long, the Power box is a large item to package, but requires only air cooling.

Supporting the control/data acquisition function of the ECU are various interfaces for specific sensors. A primary interface is the connection to the linear variable displacement transducer (LVDT) sensors, which are used for measuring the damper and thus suspension travel. An interface is required as the sampling rate is high for the suspension; for low frequencies a connection directly via the CAN bus can be used. The LVDT interface unit connects up to four five-wire sensors, and outputs the results through a CAN interface. 

Another sensor-specific interface is the tyre pressure management system (TPMS). With sensors either attached directly to the wheel or as part of the valve, they can send tyre pressure data wirelessly to an aerial mounted centrally on the car, which in turns sends the signals back to the ECU via a CAN interface. As the TPMS is not always fitted for the entire weekend, and its use is often restricted to free practice sessions, the aerial is mounted only temporarily, either on the sidepod or in many cases within a specific wing-mirror housing.

Teams may also fit an additional high speed data recorder for free practice sessions, but this must only take additional inputs or piggyback over existing sensors, as the team cannot disconnect any of the inputs to the SECU. Mounting this unit is troublesome because of its 0.6 kg weight, and its 12 x 15 cm size means it is hard to find space in the sidepods. One team mounts the unit to its front bulkhead, inside the nosecone, for testing and free practice.

The car must also be equipped with an FIA safety data recorder (SDR), which stores data from all the car’s key sensors and two FIA-specific accelerometers. These allow the FIA to use the SDR as an aircraft-style black box recorder to gather data on accidents. Should the car be in a major crash, the SDR will trigger an LED on the cockpit top to warn marshals of the severity of the accident, to allow them to take appropriate care with the driver.

Since its introduction in 2009, KERS has required specific electronic hardware, and with the expansion in 2014 of energy recovery systems (ERS) the requirement for supporting systems is growing. At the core of the ERS electronics is a control unit, which controls the power inverter and battery management. Unlike the other ERS components it manages, the controller is simply air-cooled and mounted either in the sidepod or in a complete ERS pod in the fuel tank area. There are a huge number of other smaller electronic units supporting ERS – I’m told that one 2014 system has more than 30 individual electronic units requiring air cooling.

Unconnected with the car’s operation are the driver radio and FOM camera hardware; these spec systems are provided by the FIA and are mandatory. The driver radio is mounted inside the cockpit, and of course is linked to the earpieces and microphone sewn into the driver’s balaclava. As the pit/driver radio audio is now a key part of Formula One TV coverage, the output from the radio is split and passed to both the FOM camera unit and the aerial for transmission to the team back at the pits.

For the TV feed, the car is mounted with cameras in pods around the car. The feed from the cameras is passed through a conditioning unit before passing into the FOM camera interface unit. This interface also takes feeds from the car’s GPS aerial, the car’s telemetry, external microphones as well as the driver radio. The combined output is then transmitted from an aerial on the front of the car. This allows the TV producers to have the video, audio and data to present on screen. In contrast to the car’s other electronics, the FOM camera interface is the sole area where coaxial cable is used to interconnect devices.

Fig. 1 – Formula One’s ECU was designed to be mounted in the cockpit, but sidepod mounting is also used 

Written by Craig Scarborough

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