Suhail Kazi

Modeling and control of magnetic levitation system via fuzzy logic controller

Fuzzy logic controller (FLC) is an attractive alternative to existing classical or modern controllers for designing the challenging Non-linear control systems. It does not require any system modeling or complex mathematical equations governing the relationship between inputs and outputs. Fuzzy rules are very easy to learn and use, even by non-experts. It typically takes only a few rules to describe systems that may require several lines of conventional software code, which reduces the design complexity. By considering these advantages, this paper presents the design and analysis of a FLC controller for the magnetic levitation system. Additionally, a classical PID controller is also designed to compare the performance of both types of controllers. Results reveal that FLC found to give better transient and steady state results compare to the classical PID.

Development of experimental-rig for human postural tremor behaviour

The purpose of this study is to investigate the human hand tremor behaviour in postural condition considering experimental works performed on actual human hand and a developed rig which was specifically designed to induce vibration in an intra vernacular training (IVT) hand-arm model. Two DC motors were used to spin unbalanced masses as the source of excitation to the model. Thus, this produces vibration along the hand-arm model to emulate the behaviour of postural tremor phenomenon. The quantitative assessment of tremor of the hand-arm model was mainly measured and recorded using a light-weight accelerometer and a displacement laser sensor. The accelerometer converts the physical movement into acceleration signals while the laser displacement sensor was used for precise measurement due to their high sensitivity in motion. The latter transducer was directly targeted at the palm of the hand, adjacent to the location of the accelerometer. The displacement and acceleration signals were then examined in both time and frequency domains. The results from the experiment and simulation study can be used for further analysis of human hand-arm tremor (of typically a PD patient) and the development of anti-human arm tremor device that can eventually suppress the tremor.

Selective wireless control of a passive thermopneumatic micromixer

This paper reports a novel wireless control of a thermopneumatic zig-zag micromixer by selectively activating two passive wireless heaters enabled by an external radiofrequency magnetic field. Each heater generates heat when the external field frequency is tuned to the corresponding resonant frequency (fr) of the heater. The two heaters that are designed to have different f of 100 MHz and 130 MHz are selectively activated with a constant input power of 0.2 W by modulating the field frequency to their corresponding fr. Each heater is responsible for heating an air-heating chamber that is connected to a loading reservoir through a microdiffuser element, while the solutions pumped from each reservoir are mixed in a zig-zag micromixing element that ends with an outlet hole. The micromixer provides a mixing-ratio controllability with a flow rate of ~0.28 μL/min and biocompatibility, making it promising for biomedical applications, such as local drug delivery and cells culturing.

Development of Miniature Stewart Platform Using TiNiCu Shape-Memory-Alloy Actuators

A Stewart platform is a parallel manipulator robot that is able to perform three linear movements, lateral, longitudinal, and vertical, and three rotations, pitch, yaw, and roll. This paper reports a 30 mm × 30 mm × 34 mm miniscale Stewart platform using TiNiCu shape-memory-alloy (SMA) actuators. The proposed Stewart platform possesses various advantages, such as large actuation force and high robustness with a simple mechanical structure. This Stewart platform uses four SMA actuators and four bias springs and performs a linear z-axis movement and tilting motions. The SMA actuators are activated by passing a current through the SMA wires using a heating circuit that generates a pulse width modulation (PWM) signal. This signal is varied to control the level of the displacement and tilting angle of the platform. The tilting direction depends on the SMA actuator that is activated, while all four SMA actuators are activated to achieve the linear z-axis movement. Each SMA actuator exerts a maximum force of 0.6 N at PWM duty cycle of 100%. The fabricated miniature Stewart platform yields a full actuation of 12 mm in the z-axis at 55°C, with a maximum tilting angle of 30° in 4 s.

A Hybrid Control Approach for Precise Positioning of a Piezo-Actuated Stage

Piezo-actuated stages are composed of a piezoelectric actuator (PEA) and a positioning mechanism. Hysteresis behavior of PEAs limits the position accuracy of the piezo-actuated stages. This paper presents a hybrid control approach for precise positioning of a piezo-actuated stage, where Bouc-Wen hysteresis model is used to represent the hysteresis behavior of the PEA. A Luenberger observer-based feedforward controller is designed, and then integrated with a Particle Swarm Optimization (PSO)-based Proportional-Integral-Derivative (PID) controller to form a hybrid controller. Optimal PID gains are obtained based on a fitness function proposed to reduce the displacement error and achieve fast response time. The results show that using the proposed hybrid controller reduces the hysteresis effect significantly, and thus the maximum error is minimized to 0.127 μm, which is 0.17 % of the maximum displacement of 72.1 μm.

Single input fuzzy logic controller for magnetic levitation system

Fuzzy logic controller (FLC) is an attractive alternative to existing classical or modern controllers for designing the challenging Non-linear control systems. However conventional FLC (CFLC) performance is greatly dependent on its inference rules. In most cases, the more rules being applied to a FLC, the accuracy of the control action is enhanced at the expense of longer computational time. As a result, FLC implementation requires fast and high performance processors. In this paper, it is shown that the inference rule table of a two-input FLCs used to control a magnetic levitation system can be reduced to a Single Input Fuzzy Logic Controller (SIFLC), which can be easily implemented using a lookup table. Simulated results are presented to demonstrate the equivalency of SIFLC and CFLC.

Miniature parallel manipulator using TiNiCu shape-memory-alloy microactuators

This paper reports a 30 mm × 30 mm × 34 mm mini-scale parallel manipulator using shape-memory-alloy (SMA) microactuators that poses various advantages such as a large actuation force and a high robustness with a simple mechanical structure. The developed parallel manipulator that uses four SMA actuators and four bias springs is able to perform linear z-axis movement and tilting motions. Each actuator is driven by pulse width modulation (PWM) using a microcontroller for its actuation, with a voltage and current source of 5 V and 2 A, respectively. The PWM signal is varied to control the level of actuation in terms of the parallel manipulator z-axis displacement and tilting. The tilting direction depends on the SMA actuator that is activated, while all four SMA actuators are activated to control the linear z-axis movement. Each SMA actuator exerts a maximum force of 0.6 N at PWM duty cycle of 100%. The fabricated miniature parallel manipulator yields a full actuation at 55 °C, and able to tilt a maximum angle of 30° with a temporal response of 4.7 mm/s when the PWM duty cycle is set to 75%. Movement in z-axis has a displacement range of up to 12 mm.

2D occupancy grid mapping with inverse range sensor model

This paper describes a system for occupancy grid mapping using an autonomous mobile robot equipped with laser range finder. The approach depicted in this article is the occupancy grid mapping with inverse range sensor model. A complex real time system is developed that exchange and process data between the NI robotics starter kit and an external host computer through TCP layer. All programs are developed using labVIEW. Although, the results were not as expected, the resulting maps can give an approximation of the environment of navigation. The inaccuracy of the maps is explained by the reliance on the odometry data for localization, which makes clear the necessity of simultaneous localization and mapping techniques in the field of autonomous navigation.

Design and structural analysis of Vertical Axis Ocean current Turbine

The rising energy crisis in Pakistan demands to exploit every mean of energy. Vast reserves of ocean energy in certain areas of Pakistan must be exploited in order to meet the projected energy demand. The research emphasizes on the design and validation through structural analysis of a Vertical Axis Ocean current Turbine. The research paper is supposed to be a substantial progression in this technology.

Development of hand-arm model rig for tremor excitation

This paper describes the development of a hand-arm model rig to simulate human tremor behaviour. The experimental rig is designed as an apparatus to induce vibration along a hand-arm model. An Intra Vernacular (IV) Training arm is used as the hand-arm model. Displacement and acceleration behaviour at three selected points along the hand-arm model were recorded by mean of piezoelectric accelerometer. The data from the experiment can be used for further analysis of the human hand-arm tremor especially for Parkinson’s disease (PD) patients. Results from the experiments are raw data which can later be used in designing an appropriate instrument that can suppress the hand tremor.