One of the ways in which MotoGP has attempted to control both cost and performance has been through the use of spec electronics. The first step was to make the ECU, the computer hardware, standard, allowing factories to continue to run their own software on the spec Magneti Marelli ECU adopted in 2014. This move prevented factories from developing their own specialized hardware and leveled ECU performance.
In 2016, MotoGP switched to spec software on top of the spec hardware. With everyone forced to use the same, standardized software, factories could no longer throw large numbers of software engineers at the problem to try to figure out more elegant and efficient ways of control the behavior of the bike, through traction control, engine braking, and anti-wheelie strategies. Dorna had hoped to create a level playing field with this move.
Of course, there is nothing engineers love more than challenge of finding ways to tilt a level playing field in their favor. Since the adoption of spec software, the different factories have find different ways of trying to extract an advantage from the current rules.
One of the avenues engineers have explored is the use of an IMU, an inertial measurement unit. What an IMU does is report the lean angle, attitude, and acceleration of a motorcycle. By its very nature, it requires a lot of intelligence to measure and calculate all of these factors. And the suspicion has arisen that the factories are taking advantage of that intelligence to use the IMU as a sort of secondary ECU, capable of doing more calculations and modifying the inputs to the spec ECU to change the behavior of the bike. The IMU is a so-called 'free sensor', meaning that factories are free to choose which IMU they wish to use.
Enter the spec IMU
This is about to end. From 2019, Dorna will supply a spec IMU, standardized and controlled to prevent factories from exploiting it. With the software and processing power of the IMU limited, factories will no longer be able to subtly alter the behavior of the spec ECU in pursuit of an advantage.
At Le Mans, I spoke to Corrado Cecchinelli, Director of Technology for MotoGP, about why Dorna had decided to go to a spec IMU. "For two reasons, like always," he explained. "The main reason this time is security or anti-cheating or anti-tampering, call it whatever. Because the IMU is a very important sensor that by nature includes a chip and some logic inside, so you cannot say, "you cannot put logic inside your IMU". So once you have to allow logic, you have to allow everything you can control. This is the main reason. Second reason is as always cost controlling, because as this is a free sensor everybody is trying to develop his own, which is a lot of wasted money from our perspective."
There have been suspicions around the paddock that some factories had been using the IMU as a sort of "piggyback" ECU, with the IMU taking some of the calculation load from the spec ECU, and allowing more precise control of the bike behavior. The electrical system of MotoGP bikes, like most modern vehicles, is connected using a so-called CAN bus, which effectively operates as a miniature network aboard the vehicle. All of the output of the various sensors gets sent over the CAN bus, and the ECU takes this output and makes decisions on controlling the power delivery accordingly. But as the CAN bus is an open network, all of the sensors connected to the CAN bus can theoretically read data from it, and do their own calculations based on that data. An intelligent IMU could read data from the CAN bus, then modify its own output based on that input, allowing more precise control of the ECU software strategies.
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