Sensorless position control of solenoid actuators for soft landing using super-twisting sliding mode control

Abstract

This article presents an open-loop control methodology to achieve lower seating velocities (i.e. soft-landing) for solenoid-based injector systems which are widely used in automotive as fuel injection valves or gas exchange valves of internal combustion engines to spray various fluids. Physical sensors are not preferred to be used in injectors in order to increase reliability and reduce cost. As a result, it becomes impossible to control the motion of the moving parts within injectors in closed-loop. This study offers a novel sensorless position tracking approach with which impact noise can be reduced and mechanical wear and tear can be minimized. Using the Hammerstein-Wiener modeling method and a super-twisting sliding mode controller this new approach replicates the dynamics of the injector and tracks specially designed position reference signals to achieve soft landing. The effectiveness of this approach is based on the observed negligible position and velocity errors between the estimated and actual measurements. This study also offers a new way to optimize the settling time of the injector systems, while ensuring soft landing. Using the proposed approach here, the closing profiles of the reference signals were refined according to the admittance time of the solenoid actuator and the optimal closing profile signals were selected based on performance comparisons with the baseline. The results of the experiments are presented and the promising effectiveness of the proposed approach is discussed.

Mass flow rate control of solenoid-based injectors

“…Motion tracking with super-twisted sliding mode control (STSMC) is found to be successful in non-linear motion control systems with external interference and system uncertainties. 7,9,30,31 Therefore, this control approach was also applied here.…”

“…However, it is hard to check the position of the needle, 7 as sensors are not attached to these injectors because of their cost and reliability issues. There are some studies that investigated the position control of solenoid actuators with and without sensors, 8,9 however, these controllers cannot suffice to achieve a robust mass flow rate control because solenoid-based injectors are controlled by continuous switching, and the flow behavior from the needle position cannot be predicted due to nonlinearities and other uncertainties in the system.…”