In motorcycle racing and other competitions, there is a technique to intentionally slide the rear wheel to make turns more quickly. While this technique is effective for high-speed riding, it is difficult to execute and carries risks such as falling. Therefore, an anti-sideslip control system that suppresses unintended or excessive sideslip is needed to ensure safe, natural, and smooth turning.
In anti-sideslip control, the slip angle is usually used as a control parameter. However, for motorcycles, it is necessary to know the absolute direction of the vehicle's movement. To determine this, GPS or optical sensors are required, but using such sensors for driving is costly and may not provide accurate measurements due to contamination or other environmental factors, making it impractical. Therefore, an anti-sideslip control system was developed by calculating another parameter that indicates the characteristics of the slip angle, without measuring the slip angle itself, thus eliminating the need for impractical sensors.
To detect sideslip, lean angles calculated using two different methods are used. The first lean angle calculates the true value even when side slip occurs, while the second lean angle shows a higher value than the true value when side slip occurs. The difference between these is defined as the slide amount, which can be detected as a parameter representing side slip.
When a sideslip is detected, the drive force reduction control suppresses the sideslip to bring the slide amount closer to the target slide amount. To suppress sideslip, drive force reduction through ignition retardation is used.
As an experiment, the slide amount obtained by the current method was compared with the values from a GPS device capable of calculating the slip angle. It was confirmed that the differential value of the slip angle obtained from the GPS and the slide amount had a very similar waveform. Furthermore, a test was conducted to verify whether the anti-sideslip control effectively suppressed sideslip during actual driving, and it was confirmed that applying this control allowed for more stable cornering.
The effectiveness and validity of the anti-sideslip control were confirmed through the above experiment.