Công Dũng Phạm - Academia.edu (original) (raw)

Papers by Công Dũng Phạm

2006 13th IEEE International Conference on Electronics, Circuits and Systems, 2006

Abstract Three simple logic threshold conversion circuits are proposed. The proposed simple logic... more Abstract Three simple logic threshold conversion circuits are proposed. The proposed simple logic threshold conversion circuits can be implemented using normal conventional MOS transistors. Conversion characteristics of the proposed circuit have been confirmed ...

2006 IEEE/RSJ International Conference on Intelligent Robots and Systems, 2006

Workspace analysis and optimization is a critical issue in robot manipulator design. For a Cable-... more Workspace analysis and optimization is a critical issue in robot manipulator design. For a Cable-Driven Parallel Manipulator (CDPM), due to the unilateral driving properties of the cables, maintaining positive cable tension is essential to maneuver the moving platform. As a result, its workspaces are always determined and characterized by the tension status of its driving cables. It has been realized that the Tension Factor (TF) reflecting the relative tension distribution among the driving cables is an appropriate measure to evaluate the quality of force closure for CDPMs. However, in a fully restrained CDPM, since redundant cables are employed to drive the moving platform, the TF values are not unique even for a particular moving platform pose. Therefore, how to obtain the optimal TF value so as to generate an optimized workspace becomes the major subject of this paper. It is proved that the optimal TF value can be efficiently determined through a linear optimization approach, although it is essentially a nonlinear optimization problem. Subsequently, a global tension index is proposed to evaluate the quality of the entire workspace, which is achieved by integrating the local TF values (i.e., the optimal TF values at every moving platform poses) over the workspace. Computation examples are provided to demonstrate the effectiveness of the proposed algorithms.

2006 IEEE Conference on Robotics, Automation and Mechatronics, 2006

Abstract This paper presents a novel mechanical design of a 3-DOF wrist prosthesis. Mimicking bi... more Abstract This paper presents a novel mechanical design of a 3-DOF wrist prosthesis. Mimicking biological solutions from the human arm anatomy, the wrist prosthesis is designed to have a parallel structure and is cable-driven. This results in a much lighter prosthesis, with higher ...

2006 International Symposium on VLSI Design, Automation and Test, 2006

... Using Level Shifter Technique Socheat HENG and Cong-Kha PHAM ne University ofElectro-Communic... more ... Using Level Shifter Technique Socheat HENG and Cong-Kha PHAM ne University ofElectro-Communication 1-5-1 Chofugaoka, Chofu-Shi, Tokyo, Japan, Tel: +81-4-2443-5165 ... SIMULATION RESULT Wi/L1=4A1/301A The performance of the proposed amplifier is done under ...

2007 International Symposium on Communications and Information Technologies, 2007

In this work, we propose a quick response circuit to improve the load transient response of fully... more In this work, we propose a quick response circuit to improve the load transient response of fully low dropout voltage linear regulator (LDO) which is operable with a very low power consumption. Simulating by HSPICE with 0.35μm CMOS technology shows that we can achieve the transient responses with less transient overshoot or undershoot when driving large current loads. Comparing to the generic LDO, for example, in case of 1μF decoupling capacitor, about 95% output drop and 27% settling time for 0.1mA to 100mA load current and 88% output overshoot and 63% settling time for 100mA to 0.1mA load current have been together improved. The proposed circuit only dissipates low static power, so we could achieve the above LDO with only 3.3μA consuming current at V out + 1V and 150mA load current. V out is the output voltage of the regulator.

Applied Mathematics, 2014

PAMM, 2014

The use of robotic manipulators in remote and sensitive areas calls for more robust solutions whe... more The use of robotic manipulators in remote and sensitive areas calls for more robust solutions when handling joint failure, and the industry demands mathematically robust approaches to handle even the worst case scenarios. Thus, a systematic analysis of the effects of external forces on manipulators with passive joints is presented. In parallel manipulators passive joints can appear as a design choice or as a result of torque failure. In both cases a good understanding of the effects that passive joints have on the mobility and motion of the parallel manipulator is crucial. We first look at the effect that passive joints have on the mobility of the mechanism. Then, if the mobility, considering passive joints only, is not zero we find a condition for which the parallel manipulator is conditionally equilibrated with respect to a specific external force.

Modeling, Identification and Control: A Norwegian Research Bulletin, 2014

This paper studies in detail how different evaluation methods perform when it comes to describing... more This paper studies in detail how different evaluation methods perform when it comes to describing the performance of haptically controlled mobile manipulators. Particularly, we investigate how well subjective metrics perform compared to objective metrics. To find the best metrics to describe the performance of a control scheme is challenging when human operators are involved; how the user perceives the performance of the controller does not necessarily correspond to the directly measurable metrics normally used in controller evaluation. It is therefore important to study whether there is any correspondence between how the user perceives the performance of a controller, and how it performs in terms of directly measurable metrics such as the time used to perform a task, number of errors, accuracy, and so on.