Formula Student under the Institution of Mechanical Engineers (IMechE) promotes careers and excellence in engineering by challenging a team of university students to design, build, develop, market and compete with a small single-seat racing car. Every year university teams from the UK, mainland Europe, the Americas, Asia and Australasia compete during the four-day event at the world-renowned Silverstone Race Circuit in the UK.
Formula Student is a fast-developing motorsport environment in which electronic control systems are becoming more complex, even under strict design time constraints. The current main electronic development areas include increased data acquisition rates and complex customised control systems for differentials, dampers and suspension. Using a CompactRIO PAC and LabVIEW, Oxford Brookes Racing is working to gain performance benefits for this year’s racing car by exploring the possibilities of running a complete vehicle control system, prototyping the systems away from the vehicle and validating components before putting them on the final prototype vehicle. Compared to systems used in previous years, NI products offer increasing vehicle performance gains because of the versatility of the CompactRIO and LabVIEW. CompactRIO allows shortened calculation time, better system customisation and greater hard drive capacity than our current engine management and control systems.
Engine Management and Vehicle Controls System
For the 2009 challenge, we want to use LabVIEW and CompactRIO to run the complete vehicle control system and conduct engine management, driver aid systems and data acquisition for our Formula Student vehicle. Creating the ignition and injection timing systems for a KTM EXC-530 single-cylinder engine is the most challenging aspect because these loops have to operate at very high speed and be highly deterministic for the safety and performance of the engine. The field-programmable gate array (FPGA) VI consists of a high-speed sequencing system for the camshaft and crankshaft signals that call variables from the real-time VI for values as required such as fuel pulse width, injection advance and ignition advance. The FPGA also passes the other module inputs and outputs to and from the real-time VI. We prototyped this system on a bench using theoretical engine signals and tested it using real engine signals, which operated correctly across a range of map values and engine speeds.
We also built a simple data logger and launch control, traction control and flat shift capabilities into the real-time VI. We developed the front panel of the real-time VI to simplify the mapping process with different tabs for compensations, vehicle setup and logging parameters.
Simulation and Data Acquisition
We used CompactRIO in many aspects of the project, but mainly to simulate various voltage outputs of sensors and input them into the vehicle’s wiring harness to test the functionality of the harness and control systems prior to adding particular components to the car. Using LabVIEW, we easily simulated an engine, wheel speeds and driver inputs from previously acquired data. In addition, we incorporated a pneumatic gear shift and clutch system into this year’s design. We prototyped this control system using CompactRIO to discover ideal parameters such as required pulse widths, response times and sequencing. Then we transferred the settings into the car’s engine management system for vehicle testing.
Development of our Formula Student vehicles, both past and present, has heavily relied on data acquisition. Using CompactRIO, we can log data on 30 channels and have the potential to expand to 50 with no hardware changes. Because we need to record more channels at higher logging rates, we use CompactRIO as an add-on system for one-off tests later in the vehicle’s development cycle. The car runs a 1 Mb controller area network (CAN) bus between the engine control units (ECUs) and we can store the running car data along with sensor data streamed to CompactRIO for recording on the 2 GB hard drive.
After prototyping, we replaced CompactRIO with a dedicated ECU and integrated it into the vehicle. Using a dedicated unit that was 1 kg lighter than CompactRIO helped reduce the vehicle’s total weight. However, we will incorporate systems such as active suspension in later versions of the vehicle. CompactRIO is the most viable option for future advancements because the current ECU is limited to only performing a certain number of functions, and the versatility of CompactRIO allows us to implement almost any system we need.
A future application for our products is to create a driving simulator. We want to simulate each part of the vehicle using various programs in the design phase, but we do not know the precision of the simulation until a driver operates the car. By producing a driving simulator, we can conduct more thorough sensitivity studies to determine how to best use our resources and validate design parameters.
CompactRIO and LabVIEW have offered a range of possibilities for electronic development on a Formula Student car. The 40 MHz processor allows for greater accuracy in timing and response over most current after-market engine management systems. Using LabVIEW, we can develop any new system in a short time frame. In addition, with CompactRIO our team can test components before implementing them in the vehicle by using it as a stand-alone data acquisition system, thus improving the reliability and performance of the vehicle.
We determined that CompactRIO and LabVIEW are well-suited for the fast-developing motor racing environment with more applicable uses than initially anticipated. We enhanced the performance and reliability of the vehicle through the versatility of CompactRIO, particularly in the prototyping stage. Our vehicle will travel to Hockenheim for Formula Student Germany and then to Michigan International Speedway for Formula SAE in May 2010.
Oxford Brookes University