Design and Implementation of Position Estimator Algorithm on Voice Coil Motor

Voice Coil Motors (VCMs) have been an inevitable element in the mechanisms that have been used for precise positioning in the applications like 3D printing., micro-stereolithography., etc. These voice coil motors translate in a linear direction and require a high accuracy position sensor that amounts for a major part in the budget. In this research work., an effort has been made to design and implement an algorithm that would predict the displacement of VCM and eliminate the need of high cost sensors. VCM was integrated with dSPACE DS1104 R&D controller via linear current amplifier (LCAM) which acts as a driver circuit for VCM. Sine input was given to VCM with various amplitude and frequency and the corresponding displacement is measured by using linear variable differential transformer (LVDT). The position estimator algorithm is also implemented at the same time on VCM and its output is compared with that of LVDT. It is observed that there is 97.8 % accuracy in between algorithm output and LVDT output. Further., PID controller is used in integration with the novel algorithm to minimize the error. The estimator algorithm is tested for various amplitudes and frequencies and it is found that it has a very good agreement of 99.2% with the actual displacement measured with the help of LVDT

Design & Simulation of the Engine Out Virtual Nox and Soot Sensor for Diesel Engines

The automotive field has been into a transitioning phase since stringent emission norms have been imposed by various authorities all over the world. To comply with these regulations, automotive manufacturers are coming up with new technologies and components. On the other side, there are certain issues related to the performance of various sensors used to measure engine-out emissions. Novel concepts related to combustion like the Miller cycle and low-temperature high exhaust gas recirculation (EGR) fraction are highly tested on new vehicles. These new concepts heavily depend on in-cylinder parameters like chemical composition, temperature, pressure, and flame characteristics. This leads to a complex and non-transparent engine control systems as diesel combustion itself is a complex phenomenon. This research work aspires to establish a physics-based control-oriented diesel engine combustion model to estimate in-cylinder states like a mass burnt fraction (MFB), rate of heat release (ROHR), and cylinder pressure traces based on crank angle degree (CAD). Further, comprehensive prediction models are to be designed for NOx and soot based on these states. Additionally, the impact of exhaust gas recirculation (EGR) and turbo fractions on mass exchange in the cylinder during combustion also needs to be covered to make the model more realistic. A chemical kinetics model for diesel combustion based on reactants and products involved in the combustion chemistry needs to be developed to determine the concentrations of products formed during the constant pressure and constant volume adiabatic process. This analysis is focused on the prediction of nitric oxides (NOx) and soot based on the Extended Zeldovich mechanism and Hiroyasu Kadota approach respectively. EGR significantly reduces the post flame NOx formation by introducing burnt and unburnt fractions from the exhaust gases. These gases reduce the oxygen concentration during the combustion and ultimately reducing the flame temperatures. An appropriate control strategy is to be developed to control the EGR fractions to maintain the NOx levels within the legislative limits. Additionally, fuel consumption and turbo control are needed for the optimized NOx control and fuel economy without affecting the engine performance. The proposed soot prediction model is established based on component level approach using MATLAB-Simulink as a programing tool. Some of the different subsystems involved in this model are – properties of injector nozzle, rate of heat release, in-cylinder temperature and pressure history, injection velocity of fuel jet and rate of fuel flow during the engine cycle. The conventional approach of state space design has been adopted to derive mathematical models for both NOx and soot models. As NOx model has multiple input and outputs, it is further simplified and linearized to obtain SISO system. A state feedback controller is designed for NOx model and PI controller for soot model based on the system requirements. Model validation is to be done by comparing the results to the high-fidelity GT-Power model controlled with the appropriate controller designed in the work. This GT-Power model has been developed for considering Cummins 6.7L diesel engine as a benchmark and results have been obtained for the same. The conceptual results prove the approach selected for modeling is correct as they agree with the theory behind it

A Control Oriented Soot Prediction Model for Diesel Engines Using an Integrated Approach

Diesel engines have been used in many vehicles and power generation units since a long time due to their less fuel consumption and high trustworthiness. With reference to upcoming emission norms, various engine out emissions have proved to be causing adverse effect on human health and environment. Soot, or particulate matter is one of the major pollutants in diesel engine out emissions and causes various lung related issues. There have been efforts to reduce the amount of soot generated using after-treatment devices like diesel particulate filter (DPF) to filter out particles and get clean tailpipe emissions. These technologies increase load on the system and involves additional maintenance. Also, deposition-based soot sensors have been found to be inoperative in certain scenarios like cold start conditions. In this research work, an effort has been made to develop a phenomenological model that predicts soot mass generated in a Cummins 6.7L diesel engine. The model uses in-cylinder conditions such as pressure, bulk mean temperature, fuel mass flow rate and injector orifice diameter. The difference between soot mass formed and oxidized yields the net amount of soot generated at engine out end. Furthermore, the generated soot mass is compared with benchmark results for specific load conditions and appropriate controller is designed to minimize this tradeoff. The control parameter being used here is fuel rail pressure, which controls the lift-off length, and ultimately equivalence ratio, which predicts mass of soot, generated in formation phase. The presented method shows a prediction error ranging from 5–20%, which is significantly reduced to 2% using a PID controller. The approach presented in this research work is generic and can be operated as stand-alone system or an integrated subsystem in a higher order control architecture

Characterization and System Identification of XY Flexural Mechanism Using Double Parallelogram Manipulator for High Precision Scanning

This article represents modeling of double parallelogram flexural manipulator derived from basic classical mechanics theory. Fourth order vibration wave equation is used for mathematical modeling and its performance is determined for step input and sinusoidal forced input. Static characterization of DFM is carried out to determine stiffness and force deflection characteristics over the entire motion range and dynamic characteristics is carried out using Transient response and Frequency response. Transient response is determined using step input to DFM which gives system properties such as damping, rise time and settling time. These parameters are then compared with theoretical model presented previously. Frequency response of DFM system gives characteristics of system with different frequency inputs which is used for experimental modeling of DFM device. Here, Voice Coil Motor is used as Actuator and optical encoder is used for positioning sensing of motion stage. It is noted that theoretical model is having 5% accuracy with experimental results. To achieve better position and accuracy, PID and LQR (Linear Quadratic Regulator) implementation was carried out on experimental model. PID gains are optimally tuned by using Ziegler Nichols approach. PID control is implemented experimentally using dSPACE DS1104 microcontroller and Control Desk software. Experimentally, it is observed that positioning accuracy is less than 5 μm. Further multiple DFM blocks are arranged for developing XY flexural mechanism and static characterization was carried out on it. The comparison of experimental and FEA results for X-direction and Y-direction is presented at end of paper

Design And Development Of Constant Speed Variable Discharge Pump For Various Applications

The project works deals with design & development of constant speed variable discharge pump for lathe machine. In this project the constant discharge pump is replaced by variable pump using constant speed motor. The aim of project is to obtain the variabledischarge of pump which is used for achieving various speed in various operations. The variation of discharge is achieved by arrangement of cam and follower and by using linkage to vary the discharge. For achieving variable discharge the important parameters which are to be studied are distance of linkage, cam and follower, angle of linkage. For designing cam and linkage the CATIA software is used. The testing is done by calculating time for various discharge

Design and Experimental Validation of Voice Coil Motor for High Precision Applications

Flexural structures are extensively beneficial when differentiated with conventional inflexible body structures where point accuracy positioning is strongly required extending in the range of microns. To fulfill clear and accurate positioning requirements, we come up with the solution of voice coil motors (VCM) with position estimator algorithm. Appropriate magnet and coil assembly is designed by considering the ultimate force for the application. Voice coil motor components are fabricated on milling machine and then assembled. This VCM is incorporated with dSPACE DS1104 R&D controller with the help of linear current amplifier (LCAM) which controls VCM with respect to desired amplitude and frequency. Displacement of coil of VCM is detected with respect to fixed magnet by using linear variable differential transformer (LVDT) which generates analog voltage signal in relation with motion of coil. Static characteristic such as stiffness is determined using force-deflection plot and dynamic characteristic like damping factor and frequency response are estimated with the help of transient response obtained by providing step input to the motor. Further, PID controller is implemented on this VCM and it is error observed is less than ±0.S microns