Design, analysis, and control of a MEMS micro-gripper

Research Doctorate - Doctor of Philosophy (PhD)Microelectromechanical systems (MEMS) are a key element contributing to significant developments in modern science and technologies. They offer low-cost solutions to miniaturize numerous devices. An increasing number of MEMS applications in biological research and micro industrial applications lead to noticeable demands for reliable micromanipulating tools. In this thesis, the design of such manipulators is explored via a novel MEMS micro-gripper integrated with electrothermal sensor and a novel SOI MEMS rotary micro-gripper. The presented MEMS based micro-grippers are fabricated and designed using a Silicon-On-Insulator (SOI) MEMS process to perform micromanipulation tasks in free air and in solution. A novel aspect of the first micro-gripper design presented in this thesis is the integration of innovative electrothermal displacement sensor, with a small footprint into the micro-gripper. The integrated electrothermal sensor demonstrates a linear characteristic between the measured position and the sensor output voltage, a wide sensing range (dynamic range), and a sufficient sensing bandwidth. The novelty and significance of the second micro-gripper design are due to its rotary actuation design and the implementation of a null-displacement feedback control force sensing technique where this sensing technique eliminates the dependence of the force sensor on the mechanical deformation of suspension system. Furthermore, the force calibration technique reported in this thesis is based on experimental calibration using voltage as an intermediate parameter to directly measure capacitance and angular displacement. As a result, no external device is needed for force sensor calibration. Finally, the thesis is concluded by demonstrating the feasibility of the devices and the implemented control methods through a set of practical applications such as force controlled pick-and-place operations on soft cells (Lilium pollen) and micro glass beads

Effect of Mass Media Exposure on Sexual Attitude of the Students in Bangkok Area.

รายงานการวิจัย--มหาวิทยาลัยเทคโนโลยีราชมงคลพระนคร,2549The main purpose of the study was to investigate the relation between demographic characteristics mass media exposure, knowledge and sexual attitude of the students in Bangkok area. Question aires were used to collect data from a total of 400 samples. The result of the study was as followed: 1. The mass media exposure differs significantly among the sample groups of different sex, university and income. 2. The sexual knowledge differs significantly among the sample groups of different sex, and university. 3. The sexual attitude differs significantly among the sample groups of different sex, university and income. 4. Mass media exposure does not correlate with the sexual knowledge. 5. The sexual knowledge correlates with the sexual attitude.Rajamangala University of Technology Phra Nakho

The Image of the Rajamangala Institute of Technology on the perspective of the people in Bangkok area

รายงานวิจัย -- มหาวิทยาลัยเทคโนโลยีราชมงคลพระนคร,2543The purpose of this study was to investigate the image of the people in Bangkok area and to investigate the correlation between population characteristies ,media exposur, knowledge and the image of the Rajamangala Institute of Technologe.Questionaires were used to collect data from a total of 401 samples.The results of the study were as follows: 1.RIT image was ranged in good level , even for potential of educational management ,instructors ,graduated students,mission and the image toward the institute;whereas,the appearance of the directors was in fair2.Difference in age and educational level of the population caused difference in the media expisure to information about the institute 3.Difference in educational level and career of the population caused difference in the knowledge of the institute. 4.Difference in educational level of the population caused difference in the image of the institute. 5. Media exposure to information about the institute from mass media,interpersonal media ,specialized media and activity particuoatuib correlated with the knowledge of the institute. 6. Media exposure to information about the institute from mass media correlated with the image of the directors of the institute. 7.No correlation was found between the knowledge of the institute and the image of the instituteRajamangala University of Technology phra Nakho

MEMS rotary microgripper with integrated electrothermal force sensor

A microelectromechanical systems (MEMS) rotary microgripper incorporating electrothermal force sensors is reported. The device is fabricated using a standard SOI-MEMS process and achieves a stroke of (90 µm) at a relatively low voltage (<80 V). The electrothermal force sensor has a small footprint, is quite linear, and operates with a high accuracy. Being fabricated from biocompatible material (silicon) with sufficiently long gripping arms, the gripper can be used to manipulate living cells, tissues, and other biologically relevant samples. A pick-and-place experiment on a soft cell is conducted to verify performance of the proposed rotary microgripper

Design, modeling, and characterization of a MEMS micro-gripper with an integrated electrothermal force sensor

With growing developments in biomedical research and micro industrial applications, there is a demand for micro-grippers that are reliable and can operate with high precision. This paper presents a MEMS micro-gripper with an integrated electrothermal force sensors. The microgripper is actuated by electrostatic comb-drives. Electrothermal resistive sensors are used to measure the gripping force. In this arrangement, the sensing arms deflection induces a temperature difference between two identical resistive sensors, biased at the same voltage, which results in current variation in the resistors. The currents are then converted to an output voltage using a half Wheat-stone bridge and an instrumentation amplifier. With the sensing displacement information available, the gripping force can be calculated. The device was designed and fabricated in a commercial Silicon-On Insulator MEMS foundry (MEMSCAP). A pick-and-place operation on 85 μm micro-beads on 3-axis micro-positioner is performed to evaluate the performance of the device. The experiment shows that the micro-gripper is able to handle a wide range of micro-sample sizes with biocompatibility and gentle handling forces

Model reference control for collision avoidance of a human-operated quadrotor helicopter

Because quadrotor helicopter has four fixed-pitch rotors, its control system can be much simpler than that of conventional helicopters; thus, it is expected to find wide application in many remote control situations, such as in hazardous environments. This paper proposes a collision avoidance control for a quadrotor helicopter based on the concept of a social force model. The proposed control incorporates commands given from human operators and compensates for operator mistakes in real time to achieve collision avoidance of a quadrotor helicopter. The proposed method uses distance sensors to achieve real-time collision avoidance. Its effectiveness is shown by experimental results, in which the algorithm successfully drives the helicopter along the desired trajectory without a collision

Sliding Mode Impedance Controlled Smart Fingered Microgripper for Automated Grasp and Release Tasks at the Microscale

Part 5: Gripping and Handling Solutions in AssemblyInternational audienceThe grasp and release of objects have been widely studied in robotics. At the microscale, this problem becomes more difficult due to the microscale specificities which are notably manifested by the high dynamics of microsystems, their small inertia, their fragility, the predominance of surface forces and the high complexity of integrating adapted sensors.In this paper, the problem of the grasp/release task is considered at the microscale. A new nonlinear controller design based on Sliding Mode Impedance Control (SMIC) is proposed to automate the grasp/release of the micropart. The proposed controller controls dexterously the dynamic interaction between the microgripper and the micropart and forces the system to follow the desired dynamic relation (impedance). To perform the grasp/release task, a new smart-fingered-microgripper is designed. The microgripper is composed of an active finger with integrated force sensor and a passive finger.The grasp/release of a micropart of size 50 µm $$\times$$ 350 µm $$\times$$ 2 mm is tested in experiments using the control scheme and the developed microgripper. The microgripper design and the control scheme tested show their effectiveness for the grasp/release at the microscale