A Study of Hydraulic System for Proportionalutter-height Control
Date Issued
2009
Date
2009
Author(s)
Hu, Zong-Han
Abstract
The purpose of this study is to develop an automatic control system for the cutter-height adjustment of tea pluckers. Using Automation Studio design software, the proportional control hydraulic system was simulated on the computer. The characteristics needed by the system were discovered and the feasibility of the system was tested by the simulation. A hydraulic device with a proportional valve was used for the position control. An ultrasonic sensor was also mounted on the system to detect the distance between the cutter on the plucker and the testing surface, like tea tree. A human-machine interface was built using software called Visual Basic 6.0. This interface used a RS-232 port and could receive data from an ultrasonic sensor (SRF05), Then the commands, were be sent to a proportional amplifier through a Multifunction Module called USB-4711. To establish a feedback control system, a personal computer, a proportional control hydraulic system, an A/D and D/A converter and an ultrasonic sensor were combined in this study. The system had accurate dynamic responses to the steady states by the tests with unit-step and square-wave signals. After the experiments with the ultrasonic sensor in the field, this system showed a good height tracing ability.
Subjects
hydraulic system
proportional valve
position control
human-machine interface
ultrasonic sensor
Type
thesis
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