Dunant Halim

Spatial control of vibration : theory and experiments

Modelling spatial norms and model reduction model correction spatial control optimal placement of actuators and sensors system identification for spatially distributed systems.

Virtual sensors for active noise control in acoustic–structural coupled enclosures using structural sensing: Robust virtual sensor design

The work was aimed to develop a robust virtual sensing design methodology for sensing and active control applications of vibro-acoustic systems. The proposed virtual sensor was designed to estimate a broadband acoustic interior sound pressure using structural sensors, with robustness against certain dynamic uncertainties occurring in an acoustic-structural coupled enclosure. A convex combination of Kalman sub-filters was used during the design, accommodating different sets of perturbed dynamic model of the vibro-acoustic enclosure. A minimax optimization problem was set up to determine an optimal convex combination of Kalman sub-filters, ensuring an optimal worst-case virtual sensing performance. The virtual sensing and active noise control performance was numerically investigated on a rectangular panel-cavity system. It was demonstrated that the proposed virtual sensor could accurately estimate the interior sound pressure, particularly the one dominated by cavity-controlled modes, by using a structural sensor. With such a virtual sensing technique, effective active noise control performance was also obtained even for the worst-case dynamics.

Virtual sensors for active noise control in acoustic-structural coupled enclosures using structural sensing : part II—optimization of structural sensor placement

The work proposed an optimization approach for structural sensor placement to improve the performance of vibro-acoustic virtual sensor for active noise control applications. The vibro-acoustic virtual sensor was designed to estimate the interior sound pressure of an acoustic-structural coupled enclosure using structural sensors. A spectral-spatial performance metric was proposed, which was used to quantify the averaged structural sensor output energy of a vibro-acoustic system excited by a spatially varying point source. It was shown that (i) the overall virtual sensing error energy was contributed additively by the modal virtual sensing error and the measurement noise energy; (ii) each of the modal virtual sensing error system was contributed by both the modal observability levels for the structural sensing and the target acoustic virtual sensing; and further (iii) the strength of each modal observability level was influenced by the modal coupling and resonance frequencies of the associated uncoupled structural/cavity modes. An optimal design of structural sensor placement was proposed to achieve sufficiently high modal observability levels for certain important panel- and cavity-controlled modes. Numerical analysis on a panel-cavity system demonstrated the importance of structural sensor placement on virtual sensing and active noise control performance, particularly for cavity-controlled modes.

Closed-loop control of flow-induced sound in a flow duct with downstream resonant cavities

A closed-loop-controlled surface perturbation technique was developed for controlling the flow-induced sound in a flow duct and acoustic resonance inside downstream cavities. The surface perturbation was created by piezo-ceramic THUNDER (THin layer composite UNimorph Driver and sEnsoR) actuators embedded underneath the surface of a test model with a semi-circular leading edge. A modified closed-loop control scheme based on the down-sampling theory was proposed and implemented due to the practical vibration characteristic limitation of THUNDER actuators. The optimally tuned control achieved a sound pressure reduction of 17.5 dB in the duct and 22.6 dB inside the cavity at the vortex shedding frequency, respectively. Changes brought up by the control in both flow and acoustic fields were analyzed in terms of the spectrum phase shift of the flow field over the upper surface of the test model, and a shift in the vortex shedding frequency. The physical mechanism behind the control was investigated in the view of developing an optimal control strategy.

HEV Energy Management Fuzzy Logic Control Based on Dynamic Programming

In this work an optimized fuzzy logic control strategy for Hybrid Electric Vehicle energy management is proposed. The dynamic programming algorithm is applied to obtain the optimal power distribution between engine and motor for a given driving cycle. The dynamic programming solution is also utilized for the design of the fuzzy control strategy and acts as benchmarks for comparison. The proposed strategy is based on the driving conditions; therefore, less relies on the artificial experience. The simulation results indicate that the proposed strategy can further improve the fuel efficiency compared with the conventional control strategy.

Multi-Response Parameters Optimisation for Energy-Efficient Injection Moulding Process via Dynamic Shainin DOE Method

Process parameters optimisation has been identified as a potential approach to realise a greener injection moulding process. However, reduction in the process energy consumption does not necessarily imply a good part quality. An effective multi-response optimisation process can be demanding and often relies on extensive operational experience from human operators. Therefore, this research focuses on an attempt to develop a more user-friendly approach which could simultaneously deal with the requirements of energy efficiency and part quality. This research proposes a novel approach using a dynamic Shainin Design of Experiment (DOE) methodology to determine an optimal combination of process parameters used in the injection moulding process. The Shainin DOE method is adopted to pinpoint the most important factors on energy consumption and the targeted part quality whereas the ‘dynamic’ term refers to the signal-response system. The effectiveness of the proposed approach was illustrated by investigating the influence of various dominant parameters on the specific energy consumption (SEC) and the Charpy impact strength (CIS) of polypropylene (PP) material after being injection-moulded into impact test specimens. From the experimental results, barrel temperature was identified as the signal factor while mould temperature and cooling time were used as control factors in the full factorial experiments. Then, response function modelling (RFM) was built to characterise the signal-response relationship as a function of the control factors. Finally, RFM led to a trade-off solution where reducing part-to-part variation for CIS resulted in an increase of SEC. Therefore, the research outcomes have demonstrated that the proposed methodology can be practically applied at the factory shop floor to achieve different performance output targets specified by the customer or the manufacturer’s intent.

Gear fault diagnosis using an improved Reassigned Smoothed Pseudo Wigner-Ville Distribution

Abstract The work is aimed: (i) to propose a Joint Time-Frequency Analysis method for gear fault diagnosis by using the combined autoregressive model-based filtering and Reassigned Smoothed Pseudo Wigner-Ville Distribution (RSPWVD) methods; (ii) to investigate the use of both vibration and acoustic measurements for fault diagnosis of a gear system by using the proposed fault diagnosis method. To the best of the authors’ knowledge, such RSPWVD method has not been utilized for gearbox applications due to the problem with the complexity of signals generated by the gearbox. For this purpose, experiments on a single-stage spur gearbox were carried out on a gearbox test-rig using single-defect and double-defect gear tooth faults with vibration and non-contact acoustic sensing. It was experimentally demonstrated that the proposed fault diagnosis method performed better compared to the Continuous Wavelet Transform and the Smoothed Pseudo Wigner Ville-Distribution methods. The proposed method is able to provide a more accurate indication of faults in a gearbox, even for the case of multiple gear defects using both acoustic and vibration measurements.

Clamping force control of Sensor-less Electro-Mechanical brake actuator

The brake system plays an important role in vehicles. As the X-by-wire technology develops, Electro-Mechanical Braking system (EMB) can realize individual control of braking force on each wheel; which makes it very suitable for electric vehicles. This paper aims to investigate the clamping force control method for EMB actuator without force sensor. The existing control methods are first analyzed. The modified clamping force control architecture is then proposed. In this paper, the Direct-Torque-Control technology (DTC) is applied for the precise torque control of a permanent magnet motor. In the sensor-less clamping force estimation section, an experiment-based approach is proposed. To verify the performance of the braking force control system, an EMB test-rig is established. Experimental results indicate that the clamping force of EMB actuator is well controlled under the proposed method, and the potential of EMB system for automobile application is also proved.

Control of Vibration Using Compliant Actuators

This work proposes a method for controlling vibration using compliant-based actuators. The compliant actuator combines a conventional actuator with elastic elements in a series configuration. The benefits of compliant actuators for vibration control applications, demonstrated in this work, are twofold: (i) vibration reduction over a wide frequency bandwidth by passive control means; (ii) improvement of vibration control performance when active control is applied using the compliant actuator. The vibration control performance is compared with the control performance achieved using the well-known vibration absorber and conventional rigid actuator systems. The performance comparison showed that the compliant actuator provided a better flexibility in achieving vibration control over a certain frequency bandwidth. The passive and active control characteristics of the compliant actuator are investigated, which shows that the control performance is highly dependent on the compliant stiffness parameter. The active control characteristics are analyzed by using the Proportional and Derivative (PD) control strategy which demonstrated the capability of effectively changing the respective effective stiffness and damping of the system. These attractive dual passive-active control characteristics are therefore advantageous for achieving an effective vibration control system, particularly for controlling the vibration over a specific wide frequency bandwidth.

Motion estimation for a flexible manipulator using vibration and vision sensing

This work proposed a motion estimation method for a flexible robotic manipulator with a vision-based end-effector. The effectiveness of the proposed estimation method was evaluated by utilizing a non-linear dynamic model of a flexible manipulator using the co-rotational finite element method. This modeling utilized multiple co-ordinate (co-rotational) systems which rotated and translated with each element, allowing the investigation of flexible manipulator dynamics with the large rotational and translational motion. Smart piezoelectric sensors, embedded to the flexible manipulator, were used for vibration sensing purposes. Simulation results on a flexible manipulator demonstrated the feasibility of the proposed estimation method in predicting the movement of end-effector with a satisfactory accuracy. Experimental results confirmed the effectiveness of the estimation method. Results from the vision analysis, based on experimental results, demonstrated the feasibility of the estimation method for a further flexible manipulator application with the eye-in-hand system.