Combination of map-based and adaptive feedforward control algorithms for active engine mounts

Experimental and analytical study of secondary path variations in active engine mounts

In automotive industry, engine vibration isolation has been a challenging task, and given the emergence of new vehicles with more stringent performance characteristics, engine vibration isolation has become an even more demanding issue. Most engine mounts are passive — that is, their parameter values and characteristics are fixed — and as a result, they may not properly attenuate the complicated vibration transmitted from the engine. In this paper, the development of a new active mount is described. This paper describes modeling, development, and experimental analysis of an active engine mount, which is specifically designed to address the Variable Displacement Engine (VDE) isolation problem. An electromechanical actuator is fabricated and retrofitted inside the inertia track plate of a hydraulic engine mount. The plunger of the electromechanical actuator moves upon receiving the signal from the controller, and it changes the dynamic performance of the mount accordingly based on frequency, amplitude, and phase of the activation signal. Experimental results are presented for different control signals. Simulated and experimental results are compared to validate the mathematical model. The experimental results demonstrate the performance of the designed active engine mount to deal with complicated vibration patterns, specifically those created by VDEs.

A comparison of two adaptive algorithms for the control of active engine mounts

The authors have developed a new type of active engine mount. The active engine mount is consisted of an electromagnetic actuator and an inertia-modulator hydraulic mount. The decoupler's motion is controlled by the dynamic force generated by the electromagnetic actuator .The pressure in the upper chamber is variational, as a result the total output force from the mount to the chassis is controlled. Fuzzy control method was chosen as the control method. Based on force analyses of system parts, a mathematical model of the active engine mount was established. An experimental device was designed and made. The experimental results indicated that the active engine mount can achieve better vibration isolation performance than passive engine mount.

The isolation of the body from engine vibration is the most challenging and disruptive vibrational problem. Active engine mounts (AEMs), especially electromagnetic AEMs, achieve a significant performance improvement in decreasing the wide frequency band vibration. Increasing research interest is necessary to provide the academic community with a guideline for electromagnetic AEMs. Therefore, the current review aims to comprehensively supplement the review of AEMs. The key reviews of electromagnetic AEMs focus on (1) general considerations of electromagnetic AEMs, (2) models, and (3) control strategies. This paper presents a review of the current status and developmental progress of AEMs. A theoretical model, a finite-element model, and the identification (or experimental modelling) of electromagnetic AEMs during the last 2 decades are then studied. Finally, control strategies, such as classical control, adaptive control, and two degree of freedom (2DOF) control, are discussed and compared. The main purpose of this paper is to meet the needs of researchers and engineers engaged in electromagnetic AEM analysis and control.

<div class="section abstract"><div class="htmlview paragraph">During the last decade, fuel economy mandates (CAFE regulations) have driven engine downsizing and down-speeding trends. More recently, downsized turbos are percolating down to heavier SUVs and trucks. Larger/heavier vehicles require high torque engines to provide attractive dynamic performance. While higher torque requirements can be satisfied with new innovations like the variable compression engine, larger and more upscale vehicles also need to deliver higher quietness requirements. For this, the vibration control system for combustion induced forces with high torque engines become very important. To address both dynamic performance and quietness requirements, active engine mounts have been previously adopted, however challenges for light-weighting, downsizing, and costs have still persisted.</div><div class="htmlview paragraph">A new vibration isolation technology using passive and active vibration isolation system named Active Torque Rod(ATR) was studied for application to a new vehicle to realize quietness targets with a smaller, lighter, and less expensive engine mount system. The basic concept of the active torque rod is to set it’s resonance below 200 Hz so as not to degrade the acceleration noise due to down-sizing by utilizing the passive vibration-isolation region. However, the engine primary order (2<sup>nd</sup> order) booming noise degrades due the torque rod resonance below 200 Hz. Therefore, the resonance amplitude is suppressed by utilizing an inertia mass actuator in the torque rod and inputting an out-of-phase control force corresponding to the engine 2nd order input.</div><div class="htmlview paragraph">Technical details of ATR has been previously presented by R. Yamauchi, et al. [<span class="xref">4</span>]. Therefore this paper focuses on the benefits of applying an ATR to a premium C-segment SUV under development with a new inline 4-cylinder turbocharged engine. In order to achieve the acceleration noise targets, an active upper torque rod was applied to counter the large roll reaction force input. Acceleration noise levels were reduced by about 4 dB in the 250-800 Hz range when compared to conventional (passive) torque rod system. Both acceleration noise and booming noise achieved class leading levels. The proposed mounting system is approximately 8 kg lighter than the existing active control engine mount system.</div></div>

Active control engine mount system has been developed as a noise and vibration countermeasure technology in a completed vehicle powered by a 3-liter V6 cylinder-on-demand engine. In general, engine vibration is generated by torque fluctuation from its combustion under three-cylinder operation with low rpm. The research described in this paper focuses on the fact that engine vibration is estimated from a fluctuation in crank rotation, and feedforward control algorithm without an exclusive sensor for load or acceleration is established. Then a linear solenoid actuator with high response and low heat generation is specially developed and shows high reliability due to its unique coupling structure between an excitation plate within the hydraulic engine mount and a linear solenoid. Test results from the mount installed on a vehicle show that noise and vibration performance during three-cylinder drive is similar to those at full-cylinder drive.

This paper is focused on design of a new active control engine mount (ACM), which is both compact in size and cost effective. The ACM, consisting of an electrodynamic actuator as the active element, flat springs and a sliding ball joint, is different in structure from the previous ACM designs based on the conventional hydraulic engine mount. Dynamic characteristics of the proposed ACM are extensively investigated before a prototype ACM, which meets the design specifications, is built in the laboratory. For cost effectiveness, a feed-forward control algorithm without a feedback sensor is used for reduction of the transmitted force through the ACM by the engine. The prototype ACM is then harmonic-tested with a rubber testing machine for verification of its control performance as well as adequacy of modeling. Experimental results show that the proposed ACM is capable of reducing the transmitted force by 20 dB up to the frequency range of 60 Hz.

<div class="htmlview paragraph">The feasibility of frame vibration control in automotive vehicles using active hydraulic engine mounts is investigated. The focus of the study is on engine idle conditions. A 38<sup>th</sup> dynamic model of a simplified vehicle system is used. The simplified system consists of a powertrain and a bare chassis supported by air pillow mounts at four corners. A modified LQG (linear-quadratic-Gaussian) control design method was used to synthesize a reduced order controller with improved robustness to harmonic disturbances. This modified LQG controller design is compared to a standard LQG controller.</div> <div class="htmlview paragraph">First, the conceptual implementation of active hydraulic mounts is proposed. The proposed mounts use a close-coupled servo-valve for high-speed fluid injection. The active mounts are capable of producing either attractive or repulsive forces between the powertrain and chassis.</div> <div class="htmlview paragraph">Predictions are made for levels of frame vibration reduction and actuator power consumption from simulation of closed-loop system responses. These results provide an estimate of hardware requirements for the implementation of an active mount system.</div> <div class="htmlview paragraph">Various issues in control design for flexible structures are addressed. Chief among these are the issues of model order reduction and controller order reduction. Other issues addressed are disturbance robustness and parameter robustness.</div>

Engine vibrations and noise are demanding issues in automotive industry from long times ago up until nowadays. These vibrations could be derived from rotating components, structural resonances, or combustion forces, which could potentially lead to discomfort, efficiency loss, and structural fatigue. For those reasons, vibration isolation devices have been developed to minimize these effects, such as Rubber Engine Mounts (REM), Hydraulic Engine Mounts (HEM), Active Engine Mounts (AEM), or Blance Shafts and Harmonic Dampers. This paper selects Hydraulic Engine Mounts (HEM) as the objective of study due to their remarkable damping characteristics and broad frequency effectiveness. To be more specific, traditional rubber mounts are useful for high-frequency vibration isolation but struggle with low-frequency engine operation. With the fluid damping mechanism, the HEM provides effective isolation over a broader spectrum of vibrations in both low-frequency and high-frequency conditions. On the other side, the Active Engine Mounts (AEM) bring out superior real-time vibration control, but they require sensors and electronic control units, raising up the cost and complexity of the system. According to these given drawbacks, the HEMs come out as the most advantageous solution due to their cost-effectiveness, complexity, and performance. Hydraulic Engine Mounts (HEM) are extensively used in automotive powertrains for effective vibration isolation and noise reduction, playing an important role as an energy-absorbing element, thus increasing the customers’ assuagement. The Hydraulic Engine Mount is composed of a double-chambers, an inertia track, a decoupler, and a plunger. As an energy-absorbing element, the HEM is anticipated to provide applicable frequency response characteristics under different operating conditions. Traditionally, a lumped parameter mechanical model is utilized for modeling the dynamic characteristics of HEM based on an analogy between electrical systems and mechanicalhydraulic systems, in which the system parameters are usually obtained by experiments. In this paper, a fluid-structure interaction 1(FSI) finite element analysis (FEA) and transient structural modules of ANSYS would be used to model and simulate the Hydraulic Engine Mount. The model is used to study the mechanism of Hydraulic Engine Mount and analyze key parameters of the mount for the effectiveness of vibration reduction. A CAD model of the HEM is built in Autodesk Inventor with a proper volume of the fluid in the mount with appropriate boundary conditions. Further, the model will be imported into ANSYS with fluid-solid interaction and transient structural modules to study fluid flow and understand dynamic mechanisms. The challenges in this study are to properly modify the volume of the fluid in the model to import to ANSYS Fluent Module and to set up the dynamic input boundary conditions in ANSYS Transient Structural Module before pairing these two modules in the System Coupling Module.

Due to the high stiffness, high dynamic performance, the parallel manipulator presents great advantages in the industrial manufacture. However in the machining process, the external low frequency disturbance, e.g. the varying cutting force, has a significant effect on the control system of parallel manipulator, which presents a chatter phenomenon on the end-effector of manipulator. In this paper, a feed forward control strategy is proposed to eliminate the effect of the random external disturbance on the control system of parallel manipulator. By applying the external disturbance force on the inverse dynamic model, the compensation torque is calculated and fed forward into the manipulator driving joints to cancel out the effect of the disturbance acting on the manipulator end-effector. The key issue herein is to be able to establish the accurate dynamic model for the parallel manipulator. Furthermore, in order to guarantee the position precision of the manipulator, a feed forward model-based control strategy combined with the feedback loop PV (position and velocity) control has been developed based on the reference trajectory, which could relatively simplify the highly nonlinear control system of the parallel manipulator and obtain a stable tracking error model. The whole research has been carried out on a parallel manipulator named CaPaMan which has been built in the laboratory of robotics and mechatronics in university of Cassino and South Latium. The results show that the chatter phenomenon could be utterly depressed by the force compensation from the feed forward path of the external disturbance; meanwhile the model-based controller can guarantee the trajectory tracking accuracy within a stable error by choosing the suitable PV gains.

Commercial active noise and vibration control systems for vehicles are gradually developing, mainly in Japan, for both active noise control of interior sound and active control engine mounts [1]. There have been four Japanese commercial applications: • Active control for booming noise by Nissan in 1991, • Active vibration mount for idle noise and vibration by Toyota in 1997, • Active vibration mount for diesel engines by Nissan in 1998, • Active control for low-frequency road noise by Honda in 2000. Other manufacturers have, of course, developed similar systems, but these have not progressed to production applications. Additionally, active control engine mufflers using cancelling loudspeakers have been successfully demonstrated. A new type of active muffler, using a controlled oscillating butterfly valve in the exhaust line has been developed recently. The future of active control in vehicles is dependent on customers who are willing to pay the higher price for additional noise and vibration control, so that cost reductions are the essential factor in further commercial products. Trends towards fuel efficiency and lighter vehicles run counter to reducing noise and vibration. This has given new interest in active noise control and active control engine mounts as a solution to these conflicting issues.

This thesis investigates how insects control movement using adaptive feedforward control and efference copies, and how these principles can be applied to robotic systems. A phenomenological control architecture—the fully-separable-degrees-of-freedom (FSDoF) controller—is developed to formalise efference copies in a control-theoretic context. The FSDoF architecture is used in simulation to examine control advantages of efference copy-based systems. Specifically, it enables sensors to remain within their operating range, thereby optimising sensitivity to external disturbances, and is particularly effective in systems with time delays and significant sensor noise. When combined with high-pass-filter-like sensors, the FSDoF controller also exhibits a unique robustness to changes in sensor gain and bandwidth. Furthermore, a method is introduced to design FSDoF controllers for multi-input multi-output (MIMO) systems with multiple, distinct time delays. This work formalises the efference copy hypothesis in insects from an engineering perspective, offering a functional explanation for their evolutionary advantages, and enabling the generation of experimentally testable hypotheses. One such hypothesis is that insect feedforward controllers adapt to changes in system dynamics. A series of free-flight experiments in Drosophila melanogaster supports this idea. Following unilateral wing damage, flies exhibited increased flight speeds in darkness compared to intact controls. When flying in light, with visual feedback, their speed was reduced to near-control levels. Altogether, the results indicate that the adaptation was not solely due to changes in mechanosensory feedback, but suggest adaptive feedforward control. Building on these insights, an implicit adaptive feedforward (IAFF) control strategy is proposed and implemented on a quadrotor platform. This controller uses adaptive sensitivity derivatives, so that it could, in theory, cope with an inversion of the system dynamics. IAFF control improved the reference tracking in a Parrot Mambo mini-drone within minutes of operation, starting from a randomised feedforward controller.

These years, as we require the comfort at the time of boarding, it is proposed the active control engine mount (ACM), which is the equipment for automobile vibration suppression. For one of the ACM control methods, we use the Filtered-x least-mean-square (Filtered-x LMS) adaptive control system because of the simple structure. Before we use this control method, we need the transfer model that changes controller's output voltage into ACM's thrust. But because of time-related deterioration, the model has errors, which cause system's instability. So, in this paper, we will propose the LMS adaptive control algorithm which does not have to get the transfer model in advance.

Piezoelectric actuator (PEA) is one of the key component in micro/nano manipulation equipment. However, the inherent hysteresis significantly limits its motion accuracy. In this paper, a Prandtl-Ishlinskii (PI) based feedforward and feedback compound control strategy is designed to eliminate the hysteretic nonlinearity of PEA, and thus linearizing the input/output relationship. An inverse hysteresis model is directly identified and validated using the open loop characteristics of the PEA. The inverse hysteresis model is used as the feedforward compensator. In order to further improve the performance of the PEA, a feedforward and feedback compound control strategy is also designed and tested. A PEA equipped with strain gauges is selected in the experimental investigation. Experimental results show that the hysteresis can be successfully compensated using only feedforward control, and better performance is achieved using the feedforward and feedback compound control.