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"HOLD" IS NOT ENDLESS. Before you climb into the electronic jungle of modern motorcycles, remember what we are fighting for. "Derzhak" - this is the maximum force applied to the wheel, at which it still clings to the asphalt, does not slip. Moreover, it is important to understand that, roughly speaking, the tire doesn’t care which side the force is applied from, the main thing is its maximum value. In reality, forces different in nature act on the bus. Both longitudinal impacts (during acceleration or braking) and transverse ones (in a turn) are trying to move it from the trajectory. In this case, the main thing still remains the vector sum of forces (or superposition). If, for example, we want to maximize the use of tire grip with asphalt to counteract centrifugal force, we will have to give up braking or acceleration on the arc. Or vice versa, it is possible to brake as efficiently as possible only on a straight line, any turn will require its share of adhesion in the contact patch.
But tests have long shown that the maximum “grip” on dry asphalt is achieved with a small slip, almost on the verge of transition from rolling friction to sliding friction. It is this moment that the creators of anti-lock systems are trying to use for the benefit of the pilot, while simultaneously saving them from the south, that is, sliding friction. When braking, the ABS systems allow the wheel to break into the south for some moments and right there - the electronics track the stop of the wheels very quickly - they again allow the rubber to regain traction with the asphalt. And why not make the effect work for the benefit of overclocking? This is exactly what the engineer from Honda, who developed the ABS + TCS system for the 1992 ST1100 Pan European, introduced the system. As soon as the difference in the angular speeds of rotation of the wheels (and it was measured those two decades ago through ABS sensors) exceeded a certain value, the “brain” of the engine control diverted the ignition to “late” (it was a carburetor, and there was no way to influence the composition of the mixture), and engine thrust fell sharply. It is easy to assume that in this case the difference in the angular speeds of rotation of the wheels decreased, and as soon as it reached a reasonable limit, according to the “brains”, the motor returned to normal operation.
But that system saved the motorcycle from active slippage during acceleration in a straight line, not saving from lowsides when carelessly handling the throttle stick in corners. Indeed, in a tilt, it is much easier to tear the wheel into a slip due to the fact that part of the "holder", as we recall, is spent on counteracting centrifugal force. If the sum of the forces attributable to the contact patch of the tire with the road exceeds the frictional force, the wheel will fall to the south, and the motorcycle's feed will drive out of the turn, putting the bike sideways to the turning path. Then there are three possible scenarios. First, the best: the pilot was not afraid and did not close the throttle in a panic, but dropped the gas quickly, but smoothly - and the motorcycle stabilized. The second, "continued": the pilot continued to open the gas, and after a moment the motorcycle "lay down" (lowside). Third, “brutal”: if the pilot shuts off the gas late or too abruptly, the rubber instantly regains reliable grip on the asphalt, but the kinetic energy of the “wiggle” movement makes the motorcycle jump up, roll over and kick the pilot out of the saddle (highside).
So, modern traction control systems are just fighting to keep the rear wheel on the verge of adhesion of rubber to the road surface and come into operation mainly just in the corners, when the risk of putting the rear wheel into a skid is much higher than average.
HOW DO THEY DO IT? We note right away: there are no similarities between motorcycle and vehicle traction control systems. In the world of four wheels, traction control systems not only play with engine thrust, but also brake individual wheels. We have only one driving wheel and engine traction correction exclusively in the lower direction. Motorcycle antibuks has now become such a fashionable trend that almost all motorcycle manufacturers are actively introducing such devices, but we will list the most prominent representatives of this new breed of electronic “mules”. The first systems of this century, designed to make the reaction to gas smoother and thereby combat the demolition of the rear wheel on "civilian" vehicles, began to be used on the 2007 liter gieser. There were neither wheel speed sensors (speedometer does not count), nor gyroscopes, but there was a second row of throttle valves driven by a stepper electric motor, controlled by "brains". By indirect parameters (motorcycle speed, selected gear, position of the throttle stick), the load on the motor was estimated, and based on these parameters, the controller of the ignition and injection systems, depending on the selected control program (there were three of them in all), limited thrust, or rather, speed set engine speed under a given load. A liter was followed by the “younger brothers” - they acquired multi-mode “brains”, which are even on the current “six hundred”. The “stabilizer” on the MV Agusta F4 also works on the same principle. Yes, it works, but painfully inaccurate. Unable to track the traffic situation by direct parameters (motorcycle angle, rotation speed of both wheels), this way to protect the rear wheel from demolition can only be called conditional.
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The next was the BMW concern in 2006 with a completely “civilian” R1200R. Here, wheel speeds were also monitored through ABS sensors, and, like on the ancient Pan-Europe, when the engine slipped, the ignition became later and the mixture became poorer, and the BMW ASC (Automatic Stability Control) system works much smoother and faster.
A little later, Ducati became a fighter for justice, in 2008 introducing the DTC (Ducati Traction Control) system on the 1098R model. Of course, it had little in common with the similar “stray” used in WSBK, but nevertheless there were speed sensors on both wheels (brake disc mounting bolts gave the signal) and traction correction (by changing the ignition timing and the amount of fuel supplied) was made on the basis of "live" indicators obtained in real time, although also according to the template prescribed in the memory of the control system (as in Suzuki and MV Agusta). The fundamental difference is that the slip was monitored not only through a sudden increase in the crankshaft speed, but also through the rotation speeds of both wheels. What distinguished the “civilian” traction from the racing one is that on serial sportbikes, unlike racing bikes, there are no suspension position sensors, and few people are interested in saving gasoline, and when slipping on racing Ducati the ignition was “cut”. However, if such a method is used on a serial machine with a standard exhaust, then after a couple of such anti-booster trips, the catalyst hangs on the wire from the lambda probe, so they also “chopped” fuel, sacrificing a small loss of traction due to “drying” of the intake channels. The degree of “interference” of electronics in the nature of the motor is divided into eight steps, plus the system can be turned off altogether. However, on the new Multistrada, the wheel speed is no longer read by bolts, but by ABS sensors - this is much more accurate, because if you read the speed by bolts, you get 6-8 pulses per wheel revolution (i.e. 60 and 45 degrees between pulses), and if through the "comb" of the induction sensor ABS, then you can get up to forty pulses per revolution.
But returning to the chronology of events, let's be honest, the BMW ASC system did not go further than the boxer nuked R1200R, because in 2009 DTC (Dynamic Traction Control) appeared on the sensational S1000RR sportbike - a nightmare for Japanese manufacturers. It can rightfully carry the title of a masterpiece of engineering, because it contains not only these same ABS sensors, but also a gyroscope that tracks the rolls and trim of the machine. It is thanks to the gyroscope on the S1000RR that it is impossible to “re-lock” (of course, if the DTC system is not completely turned off), as well as track the situation in the turn as accurately as possible (because if the anti-rollback is safe and works ahead of time, then less traction can be realized, which will lead to an unnecessary loss of speed) For example, in Slick mode, the engine thrust is cut by electronic throttles and nozzles, it is worth the drift of the stern, but only with the roll of the motorcycle more than 23 degrees, which implies adequately accurate handling of gas. But even during a journalistic test in Portimão, many noticed that when leaving a high-speed right turn with an ascent to the finish line, the motorcycle confidently lifted the front wheel into the air, despite the anti-virus program. BMW electronic engineers limited themselves to vague explanations about a combination of factors (tilt-lift-acceleration), which confused the electronic “brain”. In addition, from the operating experience of the editorial sports BMW, we can say that the Bavarian version of the “anti-bucks” still works roughly, leading to badass on the rubber after several track sessions.
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Kawasaki engineers did the same on the ZX-10R Ninja, which debuted this winter (Moto No. 02-2011) - there the traction control carries both the charms of a BMW DTC and some templates similar to those used on previous "ninja" (in fact, like Suzuki), which allows him to work not only in "combat", but also in a preventive mode, suppressing attempts to break the wheel to the root in the bud. But Yamaha decided that a large gyroscope was not needed on a large Super Ténéré Turenduro, and limited itself to a conventional (by today's standards) antibuks using only the readings of ABS sensors. The result - there are as many complaints as there are raptures.
LOOKING TOMORROW. In view of the increasing "electronization" of modern motorcycles, switching to electronic throttle control, as well as with the development of ABS systems, I think that in ten years traction control will appear even on scooters. And perhaps not with induction sensors, which, as you know, begin to work only when a certain speed is reached (usually 15–20 km / h), but with Hall sensors, which do not care about speed (now on most cars wheel speed sensors - “halls”).
