Communication is important in academia, but sometimes it can be difficult to understand documentation in research that one can find in journals and other academic publications. Below you can find a brief introduction to two-scale command shaping with technical language along with a clearer version written in a colloquial tone. Using simpler language in one’s research a can result in broader dissemination.
Two-scale command shaping is a strategy for reducing vibrations in conventional and hybrid electric vehicle (HEV) powertrains during engine restart. The approach introduces no additional system components and thus few additional costs. The torque profile from an electric machine (EM) is tailored to start the internal combustion engine (ICE) while minimizing residual vibrations. It is shown that the tailored EM torque profile, composed of a linear combination of constant and time-varying components, results in significant mitigation of powertrain vibrations and smoother ICE startup. The time-varying EM torque component is calculated using an analytical ICE model and a perturbation technique for separating scales, which isolates the ICE nonlinear response. Command shaping is then applied to the linear problem at the remaining scale. Simulation results suggest a promising and straightforward technique for reducing vibrations and improving drivability during ICE restart. Furthermore, two-scale command shaping may also be useful in mitigating other HEV-related drivability issues associated with powertrain mode changes (e.g., blending of hybrid power sources, engaging and disengaging of clutches, etc.).
Have you ever been unsettled by an unusual noise or shaking during your daily commute? If so, you are not alone. These events are part of a broader group of problems categorized as noise, vibration, and harshness (NVH) issues.
Unfortunately, advances in automobiles that reduce fuel consumption and harmful emissions sometimes affect a driver’s comfort by increasing NVH issues. Once such advance is engine stop-start systems in hybrid and conventional powertrains.
Engine stop-start is a functionality that prevents the engine of the vehicle from being used in times where it is not needed in conventional vehicles, such as when you are stopped at a traffic light or when the electric motor of hybrid powertrains can be used without the internal combustion engine. Turning the engine off when it is not needed saves fuel and prevents damaging emissions from escaping into the environment.
Unfortunately, engine start-stop also affects your daily drive by subjecting you to annoying and unanticipated vibrations and vehicle motion. In the past, you only had to feel your engine crank at the beginning of your drive, which is not the case with the addition of engine start-stop features.
Unwanted vibrations during engine start/stop are a growing issue in automobiles. To remove these vibrations, we developed a straightforward method of control that does not require substantial cost called two-scale command shaping (TSCS).
TSCS shapes the torque used to start/stop the engine to prevent you and your passengers from feeling the resulting vibrations from the starting/shutdown process. Vibrations are minimized by actively canceling the vibrations from the engine and minimizing the motion transmitted to you and your passengers.
With TSCS, engine start-stop features can be used to increase fuel efficiency and decrease emissions without reducing your satisfaction while you drive.