Katherine S. Peterson

Extremum seeking control for soft landing of an electromechanical valve actuator

Many electromagnetic actuators suffer from high velocity impacts. One such actuator is the electromechanical valve actuator, recently receiving attention for enabling variable valve timing in internal combustion engines. Impacts experienced by the actuator are excessively loud and create unnecessary wear. This paper presents an extremum seeking controller designed to reduce the magnitude of these impacts. Based on a measure of the sound intensity at impact, the controller tunes a nonlinear feedback to achieve impact velocities of less than 0.1m/s while maintaining transition times of less than 4.0ms. The control strategy is implemented with an eddy current sensor, to measure the valve position, and a microphone.

Modeling and Control of Electromechanical Valve Actuator

In this paper recent control developments for an electromechanical valve actuator will be presented. The model-based control methodology utilizes position feedback, a nonlinear observer that provides virtual sensing of the armature velocity and current, and cycleto-cycle learning. The controller is based on a nonlinear state-space description of the actuator that is derived based on physical principles and parameter identification. A bench-top experimental setup and a rapid control prototyping system are used to quantify the actuator performance. Experiments are conducted to measure valve release timing, transition times, and contact velocities for open- and closed-loop control schemes. Simulation results are presented for a feedforward cycle-to-cycle learning controller.

Iterative learning control for soft landing of electromechanical valve actuator in camless engines

Variable valve timing allows improvements of internal combustion engines and can be achieved by camless actuation technology. In this paper we consider an electromechanical valve (EMV) actuator. One of the main problems in the EMV actuator is the noise and wear associated with high contact velocities during the closing and opening of the valve. The contact velocity of the actuator parts can be reduced by designing a tracking controller that consists of a linear feedback and a nonsquare iterative learning controller (ILC). With the ILC methodology we update the feedforward signal of the feedback controller every cycle based on the error between the actual valve position and the desired position. The methodology is reviewed and both simulation and experimental results are presented. We explore the disturbance rejection capability of the control scheme by simulating conditions with an unknown force acting on the valve similar to the ones present during varying engine load.

Output observer based feedback for soft landing of electromechanical camless valvetrain actuator

Electromechanical valvetrain (EMV) actuators can replace the camshaft allowing for electronically controlled variable valve timing (VVT) on a new generation of engines. Before EMV actuators can be used in production vehicles two critical problems need to be resolved. First, impact velocities between the valve, valve seat, and the actuator itself need to be small to avoid excessive wear on the system and ensure acceptable levels of noise. Second, the opening and closing of the valve needs to be both fast and consistent to avoid collision with the piston and to reduce variability in trapped mass. This paper presents an observer based output feedback controller designed to achieve these goals. Theoretical analysis and experimental results of the controller are provided. The experimental results show a factor of six reduction in impact velocity and consistent and quick valve timing.

Rendering the electromechanical valve actuator globally asymptotically stable

This paper presents a nonlinear controller based on Sontags feedback to render the electromechanical valve actuator (EVA) globally asymptotically stable (GAS). Electromechanical valve actuators have received much attention recently due to their potential for improving the performance of the internal combustion engine. Various control schemes for the EVA have been proposed, however stability is often neglected due to the bounded motion of the EVA or proven based on a linearized plant model. Here, we demonstrate and prove that our controller renders the system GAS without any assumption of linearity.

Nonlinear Self-Tuning Control for Soft Landing of an Electromechanical Valve Actuator

Abstract Electromechanical valve actuators (EVA) can be used for electronic control of the engine valves. Their operation requires fast and precise motion of an armature between two stiff springs and two voltage-controlled electromagnets. Low contact velocities or “soft landing᾿ of the actuator on the solenoid faces and between the actuator and the valve is also necessary in order to maintain similar noise and wear levels with conventional camshaft-driven engines. We analyze the control difficulties, review the actuator model and extend our previous work by introducing impact dynamics. We then design a self-tuning nonlinear controller using extremum seeking that achieves impact velocities below 0.1 m/s and maximum transition time of 4.0 ms.

VIRTUAL LASH ADJUSTER FOR AN ELECTROMECHANICAL VALVE ACTUATOR THROUGH ITERATIVE LEARNING CONTROL

The reduction of impacts which occur in electromechanical valve actuators due to the presence of valve lash have been largely neglected in the literature. Instead, the majority of work in this area has focused on impacts occurring elsewhere. As such, a controller is presented here to account for the impacts which occur during the release phase of the valve opening due to the presence of valve lash. A combination of feed forward and iterative learning control are used to achieve trajectory tracking during the release bounding the impact velocity by 0.4 m/s.

Control of Electromechanical Actuators: Valves Tapping in Rhythm

Electromechanical valve (EMV) actuators can replace the camshaft allowing for electronically controlled variable valve timing (VVT) on a new generation of engines. Through the use of VVT, engine operation can be optimized to allow for improvements in fuel economy, performance, and emissions. Before EMV actuators can be used in production vehicles two critical problems need to be resolved. First, impact velocities between the valve, valve seat, and the actuator itself need to be small to avoid excessive wear on the system and ensure acceptable levels of noise. Second, the opening and closing of the valve needs to be both fast and consistent to avoid collision with the piston and to reduce variability in trapped mass. An extensive control analysis of the EMV actuator and the control difficulties are presented. Finally, a linear, a nonlinear, and a cycle-to-cycle self-tuning controllers are designed and demonstrated on a benchtop experiment.

Nonlinear Magnetic Levitation of Automotive Engine Valves

Abstract Position regulation of a magnetic levitation device is achieved through a control Lyapunov function (CLF) feedback design. The CLF is based on LQR optimal control to enhance performance. Sontags universal stabilizing feedback is used to enhance the region of attraction. The effects of magnetic saturation are included in the model, and accounted for in the controller. While the control methodology presented here is applicable to generic magnetic levitation, the controller is designed for and implemented on an electromagnetic valve actuator for use in automotive engines.