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Inside Kawasaki's Moto-GP racing bike

Posted: 23 Aug 2007 ?? ?Print Version ?Bookmark and Share

Keywords:Kawasaki MotoGP race motorcycle teardown? engine control unit? embedded software?

It's race time! Fresh off an electronics teardown of the popular Toyota Prius hybrid (see Prius drives with smart GPS navigation system), we'll look here at a whole different animala Kawasaki Ninja ZX-RR MotoGP race motorcycle. There will be no hands-on teardown of this machine, however. MotoGP is the Formula One of the two-wheel racing world, and it costs millions of dollars to get one of these prototypes on the track.

With the gracious help of Maria Serrat, Liisa Steele and Ian Wheeler of Kawasaki's GP team, I was able to spend some time with Danilo Casonato, head EFI engineer for the squad, during the July 2007 Laguna Seca race weekend. Casonato is an electronics engineer from Italy and his years spent with Aprilia (an Italian motorcycle manufacturer) were followed by the move to Kawasaki in 2002. Paddock pass and notepad in hand, I had the pleasure of poring over GP hardware up close, while learning about the electronics inside these uniquely powerful motorcycles.

Built to race
At 146.51kg and 200-plus horsepower, GP bikes are stunningly fast. As a point of reference, the current 800cc GP machines create about twice the horsepower of the 1.5L Prius gas engine in a package just 11 percent the weight of that car. Closer to the breed, MotoGP bikes have a power/weight ratio about three times that of my still-competent 600cc production Kawasaki bike. Beyond great mechanical engineering, custom fabrication and state-of-the-art tires, electronics are central to Kawasaki's MotoGP horsepower management and, accordingly, the focus of my talk with Casonato.

On-board systems tackle both data collection and engine management, with the former helping drive development of the latter. According to Casonato, "much of the time spent optimizing happens on the dyno" where track-based data and real-time feedback help with adjustments to the engine control unit (ECU) and its associated systems. As with the Prius or any other modern car, the ZX-RR's ECU maintains proper gas-air mixtures, fuel injection and spark timing and profile. But in the 18,000rpm, 200mph environment of GP, the ECU and embedded software are brought to the limits of speed, sophistication and fine-tuning.

Of course, racing doesn't happen on a dyno, so track-specific improvements are a critical overlay to time spent in the shop. Casonato describes the engineering as "one of first controlling in anticipation of the rider's actions" and, second, responding to departures from controlled performance. In direct terms, this likely means that power delivery may be adjusted up or down, depending on the bike's immediate location on a specific track. If and when things get out of shape beyond that first-order control envelope, electronics are designed to take the next, further steps to rein things in.

The ZX-RR ECU comes from Magneti Marelli of Italy, whose Marvel 4 was designed specifically for racing applications. The Marvel 4 contains two 40MIPS RISC microprocessors and an 80MFLOPS DSP along with two FPGAs. The RISC processor is joined to 1Mbyte of nonvolatile flash memory and 64Kbytes of RAM and the DSP has a similar amount of flash but 512Kbytes of RAM. A data logger internal to the Marvel 4 has 128Mbytes of storage able to gather data from as many as 512 channels at a maximum of 1,000Hz.

Kawasaki's MotoGP

Kawasaki's MotoGP is the Formula One of the two-wheel racing world.
(Click to view image.)

The Marvel 4 also implements an Ethernet interface for data download/upload and the bikes are constantly being plugged in to grab recorded data and reconfigure electronics trackside. The ZX-RR's CAN bus is also implemented in the Marvel 4, and much like any vehicle, CAN provides an interface to the ZX-RR's cockpit display unit, among the other data-sharing boxes on board.

Inspecting the Kawasaki revealed what appeared to be a second, separate data logging box from the German outfit 2D Systems; 2D supplies the ZX-RR's graphics LCD too. Analog gauges and dials are gone, with only an array of seven discrete LED shift point indicators joining the monochrome "glass cockpit" panel for delivering system information to the rider.

We didn't get into the detailed list of what is monitored on the ZX-RR, but sensors for wheel speeds, exhaust-gas oxygen (Lambda), temperatures, voltages, pressures and suspension travel are among the many likely suspects. Casonato stated that "to keep wiring harnesses manageable, analog signal multiplexing is used" within the total array of about 30 sensors on board.

Full throttle
A chopper disk visible on the front wheel serves to measure front-wheel speed by metering the pulse train generated from the chopper's slots. While not used for anti-lock braking (ABS), the unit may serve a role for wheelie control by detecting discontinuities and imbalances in wheel speed. Unlike the front wheel, a "slipper clutch" absorbs some of the back torque of downshifts, limiting one source of rear-wheel slip mechanically. That said, and while I didn't see the sensors used, electronic detection of rear-wheel spin traction-loss during acceleration is almost certainly present and used in the calculus of electronic engine management.

Throttle control is "half rider, half 'fly-by-wire,'" said Casonato, but as with many design aspects, Kawasaki closely guards details on the link between rider throttle input and actual engine manipulation. A rubber-damped potentiometer monitors throttle position, but throttle cables are clearly present. It's likely the cables directly control a portion of the throttle-body response, but electronics determine the ultimate air delivery to the engine's intake ports.

One of Kawasaki's riders for the GP races was American Roger Hayden, successful in Kawasaki's more production-based race classes and entered as a "wild card" racer for the GP event. Hayden commented openly that his GP teammates were seen in the data to grab a handful of mid-apex throttle far earlier than he was used to, requiring some "mind-over-matter" thinking to ride as aggressively in the turns. After the discussion with Casonato, it seems clear that team regulars Randy DePuniet of France and Anthony West of Australia were already riding while knowing that electronics would help keep an overeager throttle action from biting too hard.

In the end, "Team Green" did well at Laguna Seca, with their three GP ridersincluding Haydenin the top 10. Thanks to the Kawasaki Racing folks for taking time to share a bit about electrical engineering's role in the premier class of fast motorcycles. If you're into such things, catch a MotoGP race. It's delightfully raucous, and rider skills remain the front line in showcasing the engineer's efforts to deliver copious power under control and running up front.

- David Carey
President, Portelligent




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