Yoshifumi Hanamura

Analysis of steering shimmy accompanied by sprung mass vibration on light duty truck - fundamental mechanism

Steering shimmy phenomena are classified into two groups according to vehicle speeds. One is self-excited vibration at low vehicle speeds, and the other is forced vibration at high speeds. Shimmy on a light duty truck has been considered as that of self-excited vibration. However, it causes vibration not only on the steering system but also on the cabin, with a large amplitude at relatively high speeds. The phenomenon was analyzed by performing vehicle tests and numerical simulations using simplified models. As a result, the phenomenon was found to be self-excited vibration basically caused by two closed-loop vibration mechanisms.

Model-free adaptive control scheme for EGR/VNT control of a diesel engine using the simultaneous perturbation stochastic approximation

To meet the more stringent environmental requirements of automobile exhaust gas emissions, diesel engines have recently received increased attention due to their high heat efficiency. To lower fuel consumption and reduce exhaust gas simultaneously, fuel combustion must be more precisely controlled. For example, the oxygen concentration, which affects emissions, is controlled by exhaust gas recirculation (EGR) and variable nozzle turbo (VNT). However, realizing a controlled design is difficult due to system non-linearity and strong interference between EGR and VNT. Recently, various design methods have employed the so-called model-based control design, but this design approach is difficult to use when the controlled object is complex. Currently, mass production uses gain scheduling of map-based on proportional–integral–derivative (PID) control, in which each gain is tuned at various operational points. However, map calibration has many drawbacks, including time-consuming tuning, difficulty tuning during transient operations and problems adapting to the individual variations in the engine characteristics. This study proposes a construction method for a model-free adaptive PID controller using the simultaneous perturbation stochastic approximation (SPSA) and its performance is confirmed in an engine bench test.