Kawasaki's electronics control system
But mechatronics and control loops can still fall short when it comes to a human-driven activity. Despite moves by other teams to a full ride-by-wire system (where throttle application is electronically translated into acceleration of the engine) Kawasaki maintains--at least for now-- their "half-and-half" system. A physical cable from the rider throttle input controls half of the four-cylinder throttle bodies but electronic systems pick up the rest. In essence, Dosoli acknowledged a team "philosophy of feel," which keeps the rider more fully connected to the machine.
To my surprise, Dosoli indicated that real-time control based on the location of the motorcycle on the circuit had not yet fully made the transition from test track to racetrack. The system is definitely in the later stages of development and its full-time use on the race bike is fairly imminent, though Dosoli refused to be drawn on whether elements of the real-time control system are in use on the team's current MotoGP machines. What Dosoli would confirm is that GPS is the way forward for reliable position-pinning on track, as inertial navigation systems remains plagued by noise and signal ambiguities.
To be sure, data collection for later analysis relies on GPS location-stamping, but heat-of-the-moment decisions are made by learning which sensors tell the story with enough accuracy to manage the motorcycle's response to rider inputs and bike behaviors.
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Putting the power down
A two-year-old mandate reducing MotoGP engine displacement has given engineers a bit less raw power to manage. Smooth power delivery is key; the measures the ECU takes to level the peaks and valleys of engine output become more tractable when the engines are a bit smaller. Dosoli indicated that sensors for acceleration, bank angle, front-wheel and GPS-speeds, along with front-wheel suspension stroke, are the more important parameters for real-time control in Kawasaki's MotoGP machine.
Controlled wheel spin can be a racer's tool for riding fast, but too much can result in a dramatic "high-side" which bucks the rider off the bike in dangerous fashion. By comparing front- and rear-wheel speeds with GPS-speed and engine rev-up, the bike can "see" when a muted response to throttle input is needed from the traction control system (TCS) in order to maintain grip. In fact, racers coming from production-class racing to MotoGP experience the impact of unprecedented tire grip, TCS, ride-by-wire, and rich sensor-based control. Several have commented on how much sooner they can get on the gas in a turn.
So, what does Kawasaki's electronics control system look like? Of course the team will never fully say, but Dosoli acknowledged an array of about 50 sensors on board, all communicating over multiplexed ECU/datalogger feeds with CAN busses. Thirty analog sensors join with four temperature monitors, exhaust oxygen level (lambda), and a host of other digital sensors. ECU control and datalogging can get to be a busy affair. For example, the "quick shifter" strain gauge on the foot shift lever--used for timing the ignition cut-out during clutchless gear changes--benefits from KHz sample rates to get it right.
Mounds of data also demand an Ethernet interface on the race bike to download information and upload new control programs in short order. But not all the work happens at the frenzied pace of the racetrack. Post-practice and qualifying hours are spent with engineers and technicians poring over much deeper and granular acquired data to improve setup and systems for the race, and the racing season.