Anti jerk

When power is requested to the engine coming from a condition where effective torque was zero (typically, accelerating after engine brake), or on strong positive transients, effects of driveline
 elasticity, mainly due to the chain, and sudden change in Spark Advance, can cause abrupt engine response. This is when a rider is going around a bend with 0% acceleration and starts to accelerate again, here the problem: the sprockets have to be reactivated and move from neutral to pushing the motorbike forward. The chain and transmission system are not perfectly fixed, but are a little flexible. This causes a noticeable jerk effect when in use which can make the motorbike skid or even fall if it is on an incline or in a tricky position. If this happens under high lean angles, bike set could be compromised or, at least, pilot will perceive shocks that will certainly make him loose confidence and, hence, time.

To avoid this, the anti-jerk system softens the impact as much as possible. The anti-jerk maps are simple and do not usually work for few milliseconds, just as the rider accelerates. The sensors that interact with this program also monitor the amount of gas that the rider uses, the speed of the back wheel, and the engine. If either of the latter two detects a sharp increase that would cause an excessive amount of jerking, the system adjusts the pressure on the motor by a certain percentage, which can sometimes reach 100%. All of this happens in the blink of an eye — just enough to soften the jerking movement.

The feeling of the rider when start to open the gas is very delicate and have to be saved as much as possible, to get  the smoothest/fastest action, considering the hi lean angle and the low tyre contact patch involved in this phase.

Here a comment from a GP rider Bradley Smith to better explain the concept:

”Because if you start to spin the tyre at that initial touch it never comes back, which means your entire drive area will be compromised because the tyre will spin from maximum lean and continue spinning. If you can keep grip at that initial touch then you can keep it driving, which is half a bike length every corner. The smoother you can make it the better it is, but you still need a little bit of spark there, because you need to pivot the bike in that phase.”

To match this very fast movement, the reduction in torque have to be so drastic and sudden that it’s not possible to do by just closing the throttle valves (in case of throttle control) but they have to hold off the ignition or cut off the sparks. This is operated by the ecu and the amount of torque reduction is processed accordingly to the amplitude of the jerk. There is also some “security” check that make sure that this strategy will not badly effect the rider request. It is a very important strategy that works almost every corner for a very small amount of time, but it is crucial when the motorcycle works at its grip limit.

You can see in the picture how it works. The channel are the following:

Red=Engine Speed

Orange=Rear Speed

Purple=Front Speed

Cyan= Throttle Grip

The transient is very easy to see and can cause the rider to delay the throttle action.  Once the strategy is calibrated properly the rider will have much better feeling and this will result in a smoother throttle grip application, whit no hesitation or flat spot.

Share on facebook
Share on linkedin

MSE_Kawasaki ZX10RR Sbk_A software

Motorsport Engineering has recently developed and successfully tested a Superbike software by using the powerful MoTeC M170 or M130 Ecu and (targeted) to the latest world superbike championship queen, the Kawasaki ZX10RR of Jonathan Rea!!! The development of this software has been possible thanks to  Motorsport Engineering race experience together

Read More

Motorsport Engineering develop MoTeC M1 Custom packages

Aftermarket engine management system manufacturers are quickly learning that it is no longer possible for a dealer to install a replacement ECU for a modern vehicle that is including the customer requested feature. Motorsport Engineering  sells M1 Development ECUs or partner ECU on which you can load the specific customised

Read More

What IMU can do….

Do you think of how much this little box can do to keep your bike on the edge? Or do you have an idea of the complex model necessary to process all phisics motorcycle info and extract the relevant actions? Not that long ago, the idea of a bike with

Read More

Leave a Comment

Your email address will not be published. Required fields are marked *

Sign up to receive news and offers and promotions

Remember if you do not consent Event,Product, Offers we can’t send you offer and promotional email or event email.

After registering you will receive an email to confirm your email address and verify your identity.

© Copyright 2019. All rights reserved

Motorsport Engineering Andrea Torniero – Stationsstrasse 22 – 8155 Niederhasli – CHE-324.943.129

Privacy Policy

Cookie Policy

WeCreativez WhatsApp Support
Our customer support team is here to answer your questions. Ask us anything!
👋 Hi, how can I help?