Periodic Control of Automotive Vehicles to Improve Fuel Economy

This research studies the intersection of two technologies to improve fuel economy, i.e., pulse-and-glide (PnG) and cooperative adaptive cruise control (CACC). By exploiting the characteristics of internal combustion engines (ICEs), PnG periodically turns on and off the engine to save fuel. On the other hand, CACC facilitates the vehicle platooning via vehicle-to-vehicle (V2V) communication. CACC is promising to both increase the traffic throughput and reduce the fuel consumption. This research explores the possibilities for more fuel saving potential by introducing PnG into CACC. It also addresses the speed oscillation problem resulting from PnG operations, which is a challenge to vehicle platooning in terms of both string stability and ride comfort. To address these challenges, first the PnG operation of a hybrid electric vehicle (HEV) in the car-following scenario is studied with ride comfort considerations. The proposed control consists of two minimum-time control problems, one for the pulsing phase and another for the gliding phase. These two problems are solved using model-predictive control (MPC). After a series of simplification, convexification, and sparsity optimization, the two minimum-time control problems are reformulated as quadratic programming (QP) problems using the pseudo-spectral (PS) method to be solved on-line efficiently. This proposed control establishes a framework that can effectively leverage PnG for fuel savings, while satisfying the ride comfort and safety constraints. For the problem of platooning heterogeneous PnG vehicles, the concept of PnG synchronization is proposed as a solution. A control approach is developed based on the Kuramoto oscillator model to realize this concept. More specifically, individual vehicles in the platoon maintain their own virtual oscillators. With the synchronization mechanism provided by the Kuramoto model, the virtual oscillators are synchronized via only local communications. By tracking the target trajectories given by the virtual oscillators, PnG synchronization is achieved. A range-keeping approach via V2V communication is also developed. This proposed method of PnG synchronization is able to maintain the fuel saving potentials of individual PnG vehicles while keeping the platoon compact, which is ideal for achieving high throughput. The naturalistic driving data from the Safety Pilot project are utilized to analyze the levels of acceleration that people experience in everyday driving. Also, a PnG experiment is conducted using an automated Lincoln MKZ. The results from this experiment validate the fuel saving ability of the proposed PnG technique, especially at lower speeds, and offer a better knowledge about the influence of PnG operations on ride comfort.PHDMechanical EngineeringUniversity of Michigan, Horace H. Rackham School of Graduate Studieshttp://deepblue.lib.umich.edu/bitstream/2027.42/169892/1/syshieh_1.pd