- Mechatronic and Robotic Systems - Design, Modeling, Simulation and Integration
- BioMechatronics; Smart Materials-based Sensors & Actuators; Measurement Systems
- Microprocessor-based Applications
- Linear and Non-linear Control Systems Theory and Applications
- System Dynamics, Vibration, and Control
- Computer Aided Design/Engineering CAD/CAE; Industrial Automation; Manufacturing Systems
Sample Research Projects
Wireless Hybrid Mobile Robot System: Interchanging and Adaptive Locomotion and Manipulation
- Development of novel design paradigm of a hybrid mobile robot system with compounded locomotion and manipulation capability in order to enhance robot mobility and maximize functionality in field operations.
- Optimization of the mechanical design of the hybrid robotic system through dynamic simulations using ADAMS and mathematical modeling.
- Development and implementation of novel on-board wireless real-time sensor/actuator control interfaces for the hybrid mobile robot.
- Construction and integration of a prototype of the hybrid mobile robot system including the development of a computer architecture and control system design.
- Experimental setup, testing and calibrations of the integrated system.
Linkage Mechanism (LMMR) Mobile Robot with Autonomous Climbing and Descending of Stairs
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This research presents a mobile robot that achieves autonomous climbing and descending of stairs. The robot uses sensors and embedded intelligence to achieve the task. The reconfigurable tracked mobile robot has the ability to traverse obstacles by changing its tracks configuration. Algorithms have been further developed for conditions under which the mobile robot would halt its motion during the climbing process when at risk of flipping over. Technical problems related to the implementation of some of the robot functional attributes are presented, and proposed solutions are validated and experimentally tested. The experiments illustrate the effectiveness of the proposed approach to autonomous climbing and descending of stairs.
Development of Dispensing System for Microdrops Generation in Microarray Applications
- Development of a piezo-actuated dispensing system for microdrops generation with real-time closed loop pressure control to generate droplets with very high accuracy (up to several picoliters) in order to achieve very high-density microarray printing capability.
- Finite Element Modeling and Analysis using ANSYS for design optimization and performance assessment of the system and mathematical modeling and simulations using Matlab and Simulink.
- Development of control techniques using LabVIEW to achieve high accuracy and high throughput dispensing.
- Integration of a vision-based testing equipment to experimentally assess the accuracy and repeatability of the microdroplet generator and to calibrate it.
Design, Analysis and Optimization of Magnetic Microactuator
- Magnetic micro-electro-mechanical-systems (MEMS) present new class of micro-scale devices that incorporates magnetic materials as sensing or active elements. It exploits properties of magnetic materials by incorporating them in conventional microfabricated systems. Though their application for microactuation purposes has been limited, the prospect of remote control and large displacements renders them useful, and even unavoidable in certain circumstances. Recognizing the fact that poor electromagnetic flux in micro domain happens to be the most stringent limitation, measures to improve the magnetic field generated by an electromagnetic coil are studied using a microactuator that incorporates the coil and a hard magnetic film deposited on a flexure membrane. This research covers the design of a microactuator, analysis and optimization that maximizes the deflection. This study also presents an overview of magnetic microactuators covering the scaling effects, materials and processes used in their fabrication and critical review of their limitations.
Fuzzy Sliding Mode Control of a Flexible Spacecraft with Input Saturation
- This research addresses the dynamic modeling and fuzzy sliding mode control (FSMC) for a spacecraft with flexible appendages. The control objective is attitude maneuver with large angle of rotation and simultaneous vibration control. To investigate the dynamic stiffening of rigid-flexible systems, a first-order approximate model (FOAM) of the flexible spacecraft system is formulated, taking into account the second-order term of the coupling deformation field. And a lower order simplified first-order approximate model (SFOAM) is derived by deleting the items related to axial deformation, which is used for controller design. Despite the advantages of sliding mode control (SMC) for nonlinear systems, classical SMC has a major problem in the form of chattering. For highly flexible structural model, ideal sliding surface producing pure rigid body motion may not be achievable. In this research, the discontinuity in sliding mode controller is smoothed inside a thin boundary layer by using fuzzy logic (FL) technique so that the chattering phenomenon is reduced efficiently. The most distinguished feature of SMC is claimed to result in insensitivity to parameter variations, and complete rejection of disturbances. This superb system performance only holds in the sliding mode domain (SMD) on the whole switching surfaces, which is easily satisfied without input constraints. However, when the amplitude of actuators is limited by physical constraints of the actuators, SMD will be restricted to some local domain near zero on the switching surface. Thus, control input saturation is also considered in the FSMC approach. The new features and advantages of the proposed approach are the use of new dynamic equations of motion of flexible spacecraft systems and the design of FSMC by taking into account the control input saturation. Numerical simulations are performed to show that rotational maneuver and vibration suppression are accomplished in spite of the presence of model uncertainty and control saturation nonlinearity.
Dynamic Stiffening of Rotating Beams with a Tip Mass
This research aims at developing a dynamic model of a rotating beam with a tip mass undergoing large angle, high speeds maneuvering. This type of model may also be useful in modeling, analysis and development of various inertial sensors and transducers with similar operating principles. With the consideration of the second-order term of the coupling deformation field, the complete first-order approximated model (CFOAM) of a flexible spacecraft system is being developed by using assumed mode method (AMM) and Lagrangian principle. A first-order approximated model (FOAM) is obtained by neglecting the high order terms of the generalized coordinates in CFOAM. A lower order simplified first-order approximated model (SFOAM) is derived by deleting the terms related to the axial deformation. Numerical simulations and theoretical analysis show that: (i) the second-order term has a significant effect on the dynamic characteristics of the system and the dynamic stiffening is accounted for, while the traditional linear approximated model (TLAM) presents invalid simulation results; (ii) the end mass has a 'stiffening' effect on the flexible system in FOAM, but a 'softening' effect in TLAM; and (iii) the SFOAM describes the dynamic behavior well and can be used for controller design.
Design and Analysis of the FSM for Precision Laser Beams Steering
- Precision laser beam steering is critical in numerous applications. Moreover, precise pointing of laser beams is essential in challenging environments. The optical signal may be deflected, drift and wander due to environmental influences. The core problem of steering performances is to deal with the jitter disturbance. Based on the analysis of the beam angle steering system, some important factors to design the structure of a Fast Steering Mirror (FSM) and the layout of laser optics steering system are being developed. Flexure hinges with compliant mechanisms are used to build the FSM structure. A 4-quadrant detector has been used as the sensor for the incoming light. A design of the developed control loop and concepts of the FSM model are discussed. A comparison between the measured gain response and the simulation model of the FSM reveals similarity between the theoretical simulation model and the real system, and offers a way to improve the model to better resemble the real system. A laser beam jitter control test bed is also being developed to improve jitter control techniques.
Synchronous Position Control Strategy for Multiple-Cylinder Electro-pneumatic Systems
Pneumatic systems have been widely used in industrial applications because of their well-known advantages. However, pneumatic systems have disadvantages that include strong non-linearity and low natural frequency. These drawbacks make it difficult to obtain satisfactory control performances in comparison to hydraulic systems. In this research, the fundamental characteristics and nonlinear synchronous control strategy of pneumatic systems are studied. The two-layer sliding mode synchro system with feedback linearization based on friction compensation is applied to electro-pneumatic cylinders and synchro PID controller is applied to these position systems. To validate the developed strategies, experiments with two-cylinder electro-pneumatic systems are performed. The experimental results show that the synchronous position control design is effective in both accuracy and robustness.