A novel optimal control strategy for regenerative active suspension system to enhance energy harvesting

The conventional onboard actuators in the active suspension system (ASS) consume a high amount of external energy, which restricts their application in reducing the effects of vehicle body vibration caused by road roughness. To address this limitation, the energy-regenerative active suspension system (RASS) based on the electromagnetic structure has been introduced. This paper presents a new optimal control algorithm for the RASS that directly considers energy regeneration in combination with ride comfort in its performance index. The proposed algorithm can be tuned to direct the working points towards high energy regeneration zones. Meanwhile, it employs a realistic nonlinear model of the suspension system to achieve high performance. By applying proper operating electric circuits, the performance of the RASS under the proposed controller is studied for various road conditions. The obtained results indicate that the proposed control strategy delivers lower acceleration over the human body-sensitive frequency range based on ISO2631-1, despite harvesting energy. For instance, when the vehicle travels on a random road with a velocity of 12 m/s, the proposed nonlinear control strategy with a suitable weighting factor increases the capacitor voltage from the initial value of 20 V to 40 V during a 15 s interval. This shows a 31% increase compared to the case where the weighting factor is taken to be zero, according to the previous strategies. Additionally, the proposed strategy by the nonlinear controller remarkably increases the harvested energy compared with a linear optimal controller.