Auto racing has become a game of precision. Not only are the cars designed and built using the most precise measures, but the rules of the race also dictate limits on these designs.
The rule book for Indy Racing League (IRL) events stipulates maximum and minimum heights for certain parts of the car in reference to other components as well as to the ground. For example, the tunnel exits must be within certain distances in reference to the bottom of the car. Measurements are determined by the rules of each event. In the past these measurement were made by hand. They were referenced from a flat plane placed against the bottom of the car. This created its own difficulty because the car being measured can be at an arbitrary plane with reference to the ground. This situation is compounded for an oval track. For such a race, the car uses different diameter wheels on the left side and the right side. Further, cars designed for an oval track are built to have a certain pitch even before the tires are factored in. These variations create a tenfold problem in providing accurate rule-book measurements.
The IRL needed a better way to measure race cars, and contracted several consulting firms, including Pi Research to carry out the electronic design necessary to meet the specific measurement requirements set by the rule book. The companies worked together to design an automatic XYZ positioning system that would provide the necessary measurements within two minutes.
The IRL Tech Pad is an automated system now used to qualify entrants in all IRL racing events. The Tech Pad incorporates six range finding lasers, which are part of the Pi Research product range, to establish a reference plane for each critical measurement. This reference plane is located by measuring the underbelly of the car. Software written in C++ calculates a transfer matrix, which maps the orientation of the car (the flat plane as selected) to the ground. The use of this system quickly calculates the height of any point on the underside of the vehicle to assure it is within IRL regulations.
Pi Research designs and manufactures all measure of electronics for the motorsport industry. This includes control systems and data acquisition hardware and software for Formula One, CART, IRL, NASCAR, World Rally Car, Touring Car, LeMan Prototypes, ALMS, and even for club markets like motor bikes, karting, and snowmobiles.
According to Daniel Bryars, applications field engineer for Pi Research, "When we needed motors and controls for the Tech Pad system, we turned to Maxon Precision Motors USA for several reasons." In order to stick to design and manufacturing lead times, Pi Research first needed to use off-the-shelf motors and motor controls. Besides the fact that Maxon is a large and reliable international company, Maxon and Pi had also worked together on several projects before the IRL project was acquired. Still, according to Bryars, "Research for the project found that Maxon components provided the size and power specifications we needed to move the loads involved."
The positioning system is made of a steel and aluminum structure, which incorporates ball screw technology. Maxon''s 32mm, 80 watt brushless motor is used for the X axis, while the company''s 45mm, 250 watt motor is used for the Y axis. Both motors are equipped with a three-channel line driver encoder for position feedback. Additionally, two 45mm motors are also used to drive the two axes loaded with the lasers.
The entire positioning system for the Tech Pad is controlled by Maxon''s MIP50 controller. The MIP 50 interfaces using an RS485 port to allow multiple units to be multi-dropped in a parallel configuration. Units are configurable for DC brush or brushless motors. The controllers offer PID position control and PI current control.
Accurate positioning is a must for the IRL application. Maxon motors and controls provided XY positioning accuracy for the laser heads to within +/-5microns (including mechanical backlash). The lasers themselves measure the Z axis, and are accurate to within +/-50microns.
Every project of this nature requires that vendors work closely together throughout the process. According to Bryars, "The customer support and ISO 2001 order process used by Maxon was very attractive from the start." He also commented that technical support was good and the response from all offices, including applications sales and the home office, was excellent. "This was especially true for the documentation and code production for the Tech Pad system," Bryars said.
At completion, the IRL Tech Pad was a success. The system will make it easy to take key rule-book measurements accurately, allowing the IRL to better control the necessary specifications for highly specialized races.