Browsing by Author "Chen, T. L."

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A novel fault-tolerant sensor system for sensor drift compensation
(2008-10-03)
Chen, T. L.
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You, R. Z.
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機械工程學系
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Department of Mechanical Engineering
The conventional fault-tolerant sensor systems would fail when outputs from incorporated sensors are either noisy or drifting. This paper presents a novel real-time fault compensation method, which uses state estimation and compensation techniques, that the sensor system can perform robust measurements even when outputs from every incorporated sensor are noisy and drifting. In a simulation example, the proposed design can detect and correct the sensor errors (dc bias and drift) in real time. For the dc bias, the minimum detectable offset value is 0.1, which is the same as the standard deviation of the sensor noise. The compensated sensor output is biased at values smaller than 0.02. For the sensor drifts, the proposed method can compensate drifts for the change rate of drifts up to four times faster than that of the signal to be measured. The highest change rate of drifts, that can be compensated by this method, is determined by the standard deviation of the sensor noise. (c) 2008 Elsevier B.V. All rights reserved.
Design and analysis of an orientation estimation system using coplanar gyro-free inertial measurement unit and magnetic sensors
(2008-06-15)
Kao, C. F.
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Chen, T. L.
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機械工程學系
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Department of Mechanical Engineering
Conventionally, there are two ways to determine the orientation angles of an object. One uses 3-axis accelerometers and 3-axis magnetic sensors, while the other one uses additional 3-axis gyroscopes to achieve a higher sensing accuracy than the first one. This paper presents a novel orientation estimation system that uses seven single-axis linear accelerometers and 3-axis magnetic sensors. These seven linear accelerometers are deployed in a way to form a "coplanar" gyro-free inertial measurement unit (IMU). As such, they can perform the integrated measurements of gravity force and angular velocity for the subsequent sensor fusion algorithms. With the information of the angular velocity, this novel design achieves a comparable performance with the one that includes 3-axis gyroscopes. The analysis of the system observability indicates that the angular velocity measurements can improve the observability of the angle estimation under certain circumstances. This result suggests the possibility of using fewer sensors in an orientation estimation system. Simulation results indicate that the proposed design achieve a sensing accuracy of 0.11 degrees, 0.09 degrees, and 0.2 degrees for the roll, pitch, and yaw angle; this leads to the improvement of 540%, 632%, and 754% over the one that does not include the measurement of the angular velocity. (C) 2008 Elsevier B.V. All rights reserved.
Design and implementation of a dual-antenna GPS receiver
(2020-01-01)
Lin, Y. Y.
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Hsu, T. H.
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Chen, T. L.
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機械工程學系
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Department of Mechanical Engineering
In the Global Position System (GPS) technology, the GPS receiver (GPSR) has to receive the satellite signal to locate its position in a 3D space. For the GPS applications where the GPSR carrier (vehicle) is rotating, the signal-receiving-path could be temporally blocked by the attitude of the vehicle. And, once the GPSR loses track of the signal, it takes at least 6 seconds for the GPSR to resume its positioning task. This paper proposes a novel dual-antenna GPSR system (hardware architecture and algorithms) that can solve the intermittent signal problem when the vehicle is rotating and continuing on its positioning task. Current experimental results indicate that the proposed GPSR design can successfully output its position when the vehicle is rotating at 7.5 rpm. At 22 rpm, some satellite signals remain on-lock but some do not, depending on the strength of receiving signals.
Design of Missile Mid-Course Guidance for Constrained Impact Angle
(2020-01-01)
Chen, B. H.
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Chen, T. L.
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機械工程學系
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Department of Mechanical Engineering
This research develops a mid-course guidance law, which enables a constrained impact angle at the engagement, in response to the needs of modern missile design. To achieve this goal and share the workload with the terminal guidance, the mid-course guidance has to regulate the missile to a specific target location and a specific flight angle for a specific "time-to-go." Therefore, conventional mid-course guidance laws are inadequate in this case. The proposed guidance law achieves this goal by recursively updating the target dynamics for the mid-course guidance, and applying optimal controls with frequently updated control parameters. Simulation results demonstrate the importance and effectiveness of the proposed method. In a simulation case, the interception missile is 100 kilometers away from the target missile, the flight speed of the two missiles are 1200 m/s and 800 m/s, respectively, and the requested impact angle is 150 degrees. The proposed method achieves the positioning error and flight-path-angle error of 791 meters and 0.56 degrees, at the end of mid-course guidance. When working with the previously developed terminal guidance, the miss distance and impact-angle error are 0.002m and 0.001 degrees at the end of the engagement.
Modelling and Control of Quad Hybrid Engine Levitating Platform
(2020-01-01)
Hou, Y. J.
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Chen, T. L.
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機械工程學系
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Department of Mechanical Engineering
This research aims to develop trajectory controls for a levitation platform which is powered by rocket fuel. This control task is to regulate the platform for 3D trajectory followings and suspension in the air, which is different from that of the most rocket systems. To cope with the challenges of slow thrust response and coupled vehicle dynamics, we proposed a control system that consists of 4 independent loops for the height, yaw angle, x-position, y-positions, respectively. The developed controllers include 4 PID compensators for the flow rate throttling system, and four double phase lead and two lead-lag compensators for the vehicle dynamics. According to the simulation results, the levitation platform can follow a designated trajectory well when there exist external torques disturbance. (both 1 N-m step inputs and 0.1 N-m Gaussian distributed input) and 2% thrust force oscillations.
PD-SOI MOSFET Body-to-Body Leakage Scaling Trend and Optimization
(2008)
Lo, H. C.
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Luo, W. C.
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Lu, W. Y.
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Cheng, C. F.
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Wu, Benny
Body-to-Body leakage (BBL) in stacked transistor configuration has been characterized by different back gate biases (Vbg), SOI thicknesses, and poly spacings. BBL increases significantly from 65nm to 45nm node mainly due to smaller poly spacing and shallower S/D junctions. By implant optimization and reduction of the SOI thickness, BBL can be reduced below reverse junction leakage level.
The Characteristics and Control of Body-to-Body Leakage Current in PD-SOI
(2009)
Lo, H. C.
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Luo, W. C.
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Lu, W. Y.
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Cheng, C. F.
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Chen, T. L.
Body-to-body leakage (BBL) current in a partially depleted silicon-on-insulator (PD-SOI) device is increased significantly as polyspacing (PS) is reduced in technology scaling. We found out that the BBL has a great impact to Vt variation. We have demonstrated that the BBL can be minimized drastically by implant optimization. The dependence of the BBL on silicon film thickness, e-SiGe structure, and dopant diffusivity is also discussed in this paper. The layout effect of the BBL current in PD-SOI devices has been characterized with different PSs, device widths, and polylengths. Finally, we have demonstrated that the BBL current can be reduced below junction leakage level. (C) 2009 The Electrochemical Society. [DOI:10.1149/1.3223971] All rights reserved.