• 오토저널
• /
• 제15권3호
• /
• pp.81-88
• /
• 1993

This report describes the experimental research on the flow phenomena of the aq uaous polymer solution within the Cuette flow of the concentric, cylinders type with a wide circular gap. We have investigated the phenomena of the fluid flow through torque measuring in the system that the inner cylinder is stationary and the outer one is rotating. Geometrical parameters of the system are the gap ratio of t/R$_{0}$=0.2 and Aspect ratio of l/t=100. The torque increases considerably in about 420-480RPM, So, it is considered a turbulent transition boundary, the higher plymer concentration is, the lower torque value is and the higher transition Reynolds number is. In each of the polymer concentration, the unstable boundary of torque, that is, idiosyncrasies of torque is observed around 220-280RPM. and the boundary is looked upon as a resonant vibration which is caused by the inner cylinder and tortional vibration of torque sensor.r.

• 제어로봇시스템학회논문지
• /
• 제22권1호
• /
• pp.31-39
• /
• 2016

This paper describes the design of an ankle rehabilitation robot for the force measurement of a severe stroke patient staying in a bed ward. The developed ankle rehabilitation robot was attached to a three-axis force/torque sensor that could detect force Fx, Fz, and torque Tz and measure the ankle rotation force (Fx) exerted on the ankle and the signal force Fz and torque Tz to be used as a safety device. The robot was designed and manufactured for bedridden stroke patients, and the robot program was manufactured to perform the flexibility rehabilitation exercise for ankle bending and to measure the ankle force to judge the degree of rehabilitation. According to the result of the characteristics test of the developed rehabilitation robot, it was safely operated while the ankle-bending flexibility rehabilitation exercise and the emergency situation were performed. Therefore, it is thought that the developed rehabilitation robot can be used for severe stroke patients.

• Ocean Systems Engineering
• /
• 제14권1호
• /
• pp.53-72
• /
• 2024

The interaction of the blade of surface-piercing propellers (SPPs) with the water/air surface is a physical phenomenon that is difficult to model mathematically, so that such propellers are usually designed using empirical approaches. In this paper, a newly developed mechanism for measuring the torque of SPPs in an open water circuit is presented. The mechanism includes a single-component load cell and a deformable torque sensor to detect the forces exerted on the propeller. Deformations in the sensor elements lead to changes in the strain gauge resistance, which are converted into voltage using a Wheatstone bridge. The amplified signal is then recorded by a 16-channel data recording system. The mechanism is calibrated using a 6-DoF calibration system and a Box-Behnken design, achieving 99% accuracy through multivariate regression and ANOVA. Finally, the results of performance tests on a 4-blade propeller were presented in the form of changes in the torque coefficient as a function of feed rate. The results show that the new mechanism is 8% more accurate than conventional empirical methods.

• Journal of international Conference on Electrical Machines and Systems
• /
• 제1권3호
• /
• pp.266-273
• /
• 2012

In conventional direct torque control (DTC) using space-vector modulation (SVM) of induction machine (IM) drives, at least three current sensors are needed. In this paper, a low-cost SVM-DTC strategy is proposed, in which only a single current sensor is used. The position of the voltage space vector is divided into two areas: effective and non-effective area. If it is located in the non-effective area, the voltage space vector will be shifted into the effective area with minimum distortion. Further, the switching frequency remains constant. The simulation is carried out on a MATLAB/Simulink platform and the simulated results verify the effectiveness of the proposed strategy.

• 전기학회논문지P
• /
• 제66권2호
• /
• pp.53-57
• /
• 2017

This papers propose a Hall-effect sensors position error compensation method in a sunroof system using a BLDC motor with a low-cost MCU. If the BLDC motor is controlled with this wrong position, the torque ripple and operating current can be increased and the average torque also decreases. Generally, sunroof system has characteristics that operate at constant load for several seconds. It is possible to find the minimum operating current value while changing the position of the Hall-effect sensor during the sunroof operation by using these characteristics. Therefore, propose a method to change the Hall-effect sensor position and find the minimum current value. The validity of the proposed algorithm is verified through experiments.

• 대한기계학회논문집A
• /
• 제28권3호
• /
• pp.222-229
• /
• 2004

In this paper, the torque of CNC spindle motor during machining is estimated without speed measuring sensor. The CNC spindle system is divided into two parts, the induction spindle motor part and mechanical part. In mechanical part, the variation of the frictional force due to the increment of the cutting torque and the effect of damping coefficient is investigated. Damping coefficient is found to be a function of spindle speed and not influenced by the weight of the load, while frictional force is a function of both the cutting torque and spindle speed. Experimental equations are drawn for damping coefficient and Coulomb friction as a function of spindle speed. Incremental frictional torque Is also obtained as a function of both cutting torque and spindle speed. Graphical programming is used to implement the suggested algorithm to monitor the torque of an induction motor in real time. Torque of the spindle induction motor is estimated well in about average 3% error range under various cutting conditions.

• 농업과학연구
• /
• 제46권4호
• /
• pp.723-735
• /
• 2019

The power-train is the most important component of an agricultural tractor. In this study, the strength of the driving gear transmission of an 82 kW-class tractor was analyzed using equivalent torque during plow tillage. The load measurement system consisted of an engine revolution speed sensor, torque-meters, revolution speed sensors for four axles, and pressure sensors for two hydraulic pumps. The load data were measured during plow tillage for four speed stages: F2 (2.78 km/h), F5 (5.35 km/h), F7 (7.98 km/h), and F8 (9.75 km/h). Aspects of the gear-strength such as bending stress, contact stress, and safety factors were analyzed under two torque conditions: the equivalent torque at the highest plow load for the F8 speed stage and the maximum engine torque. The simulation results using KISSsoft showed that the maximum engine torque conditions had a lower safety factor than did the highest equivalent torque condition. The bending safety factors were > 1 at all gear stages, indicating that gear breakage did not occur under actual measured operating conditions, nor under the maximum torque conditions. However, the equivalent torque condition in the contact stress safety factor was > 1, and the maximum torque condition was < 1 at the first gear pair. The method of analysis using the equivalent torque showed lower stress and higher safety factor than did the method using maximum torque. Therefore, when designing a tractor by applying actual working torque, equivalent torque method would support more reliable product development.

• Journal of Electrical Engineering and Technology
• /
• 제2권4호
• /
• pp.505-512
• /
• 2007

The object of this paper is to study a new control structure for sensorless induction machines dedicated to electrical drives using a three-level voltage source inverter VSI-NPC. The amplitude and the rotating speed of the flux vector can be controlled freely. The scheme investigated is an Enhanced direct torque control "EDTC" for electric vehicle propulsion. The considered application imposes some constraints which are achieved in EDTC control (fast torque response, optimal switching logic, torque control at zero speed, and large speed control. The results obtained for an induction motor indicate superior performance over the FOC type without need for any mechanical sensor.

• 한국군사과학기술학회지
• /
• 제12권3호
• /
• pp.388-395
• /
• 2009

Surveillance Radar System for naval vessels is a primary core sensor for command and fire control, and provides CFCS(Command and Fire Control System) information for 3-D surveillance and fire control. It's composed of Antenna, Transmitter/Receiver, Signal Processor, and Air drier, which are installed on and under deck. They should be designed and produced in order to endure at any operating circumstances. This paper analyzes load of a driving part for driving the antenna considering factors under external operating circumstances, and proposes a condition of load for maintaining fixed RPM through analyzing internal load of the driving part, and how to reduce the load to meet the condition. This paper is verified through experimental studies.

• 로봇학회논문지
• /
• 제15권4호
• /
• pp.309-315
• /
• 2020

This study shows a control strategy that acquires both precision and manipulation sensitivity of remote center motion with manual traction for a surgical assistant robot. Remote center motion is an essential function of a laparoscopic surgical robot. The robot has to keep the position of the insertion port in a three-dimensional space, and general laparoscopic surgery needs 4-DoF (degree-of-freedom) motions such as pan, tilt, spin, and forward/backward. The proposed robot consists of a 6-axis collaborative robot and a 2-DoF end-effector. A 6-axis collaborative robot performs the cone-shaped trajectory with pan and tilt motion of an end-effector maintaining the position of remote center. An end-effector deals with the remaining 2-DoF movement. The most intuitive way a surgeon manipulates a robot is through direct teaching. Since the accuracy of maintaining the remote center position is important, direct teaching is implemented based on position control in this study. A force/torque sensor which is attached to between robot and end-effector estimates the surgeon's intention and generates the command of motion. The predefined remote center position and the pan and tilt angles generated from direct teaching are input as a command for position control. The command generation algorithm determines the direct teaching sensitivity. Required torque for direct teaching and accuracy of remote center motion are analyzed by experiments of panning and tilting motion.