  This paper proposes an ecological adaptive cruise control (EACC) concept with
the primary goal to minimize the fuel consumption in a city bus with an
internal combustion engine (ICE). A hybrid model predictive control (HMPC) is
implemented in this work to control both continuous and discrete-time
variables. Moreover, a multi-objective optimization problem for EACC is
formulated in time-domain as a mixed-integer quadratically constrained
quadratic programming (MIQCQP) problem. The proposed HMPC-EACC performs robust
vehicle-following while tracking a leading vehicle and plans fuel-efficient
acceleration and deceleration maneuvers for the host vehicle. Additionally, it
uses the signal phase and timing (SPaT) information to compute a green wave
reference speed for the host vehicle to cross the signalized intersections at a
green phase. Moreover, the proposed controller performs pulse and glide (PnG)
to optimally control the engine ON and OFF states and save additional fuel.
Furthermore, the performance of the proposed strategy is evaluated on a
real-world driving profile and compared against a baseline controller from the
literature. Finally, the influence of different prediction horizons on the fuel
savings and computation times are studied. The results reveal significant
reduction in fuel consumption with HMPC-EACC and demonstrate that the proposed
controller is real-time capable.
