CMOS ring oscillator delay cell performance: a comparative study

A common voltage-controlled oscillator (VCO) architecture used in the phase locked loop (PLL) is the ring oscillator (RO). RO consist of number of inverters cascaded together as the input of the first stage connected to the output of the last stage. It is important to design the RO to be work at desired frequency depend on application with low power consumption. This paper presents a review the performance evaluation of different delay cell topologies the implemented in the ring oscillator. The various topologies analyzed includes current starved delay cell, differential delay cell and current follower cell. Performance evaluation includes frequency range, frequency stability, phase noise and power consumption had been reviewed and comparison of different topologies has been discussed. It is observed that starved current delay cell have lower power consumption and the different of the frequency range is small as compared to other type of delay cell

Integrating Retrofit IOT Controller With Electric Power System For Manual Wheelchair

Persons with physical injuries and disability are struggling to get through places using the conventional handwheelchair The needs of many people with disabilities can be overcome with powered wheelchair, but some portion of this community is finding it difficult to operate standard powered wheelchair due to its big in size and epensive.. This project developed a smatphone phone-controlled wheelchair along with three types of virtual controller which is Joystick control, D-pad control and Voice control through the wireless communication.. It is also equipped with obstacle (ultrasonic) avoidance notification and microcontroller controls the motor that moved the direction either FRONT, BACKWARD, LEFT and RIGHT. The main objective of this project is to facilitate and increase the movement of people who are handicapped and the ones who are not able to move freely with the implementation of IoT platform where this platform could provide data visualization and able to analyze the wheelchair maintenance management and movement. In additional, this project analyzes distinct IoT monitoring system features, including battery level remaining and temperature control. the concept succesfully developed with integration of microcontroller in which provide desired performance control  of the system to desired output with the synchronization of Internet of Thing feature

Wireless Voice-Based Wheelchair Controller System

In this paper, we present our work called wireless voice-based wheelchair controller system, which consists of an Android device and a control system that controls the movement of wheelchair using a DC motor. This project is aim to ease the burden for wheelchair user especially for elderly people to move around. The control system is build using the Yo-Yo (IOIO) platform that controls the DC motor, communicates with the Android phone application using RF receiver through a Bluetooth communication protocol and RF signal. The Android application is developed using Basic-4-Android (B4A) rapid development tool connected with one main control interface using voice command, D-pad and joystick to control the motor driver MD30C direction and speed through IOIO platform based on four conditions; forward, backward, right and left. The speed movement is controlled by Pulse Width Modulation (PWM) signal while the direction movement for Qibla’ is generated by the control interface and guided by an electronic compass in the Android device. While there are some limitations in the cost and direction movement, the concept developed in this project are proven convenience innovation and provides better benefits to the targeted market and public interest

FPGA based high precision torque and flux estimator of direct torque control drives

This paper presents an improved FPGA-based torque and stator flux estimators for direct torque control (DTC) induction motor drives, which permit very fast calculations. The improvements are performed by 1) using two"s complement fixed-point format approach to minimize calculation errors and the hardware resources usage in all operations, 2) calculating the discrete integration operation of stator flux using backward Euler approach, 3) modifying the non-restoring method to calculate complicated square root operation of stator flux, 4) introducing a new sector judgment method, and 5) reducing the sampling frequency down to 5µs. To avoid saturation due to DC offset present in the sensed currents, the LP Filter is applied. The simulation results of DTC model in MATLAB/Simulink, which performed double-precision calculations, are used as references to digital computations executed in FPGA implementation. The Hardware-in-the-loop (HIL) method is used to verify the minimal error between MATLAB/Simulink simulation and the experimental results, and thus the well functionality of the implemented estimators