In this thesis study, a valveless hydraulic servo system controlled by two
pumps is investigated and its performance characteristics are compared with a
conventional valve controlled system both experimentally and analytically. The
two control techniques are applied on the position control of a single rod linear
actuator. In the valve controlled system, the flow rate through the actuator is
regulated with a servovalve / whereas in the pump controlled system, two variable
speed pumps driven by servomotors regulate the flow rate according to the needs of
the system, thus eliminating the valve losses.
To understand the dynamic behaviors of two systems, the order of the
differential equations defining the system dynamics of the both systems are reduced
by using the fact that the dynamic pressure changes in the hydraulic cylinder
chambers become linearly dependent on leakage coefficients and cylinder chamber
volumes above and below some prescribed cut off frequencies. Thus the open loop
speed response of the pump controlled and valve controlled systems are defined by
v
second order transfer functions. The two systems are modeled in MATLAB
Simulink environment and the assumptions are validated.
For the position control of the single rod hydraulic actuator, a linear state
feedback control scheme is applied. Its state feedback gains are determined by
using the linear and linearized reduced order dynamic system equations. A linear
Kalman filter for pump controlled system and an unscented Kalman filter for valve
controlled system are designed for estimation and filtering purposes.
The dynamic performances of both systems are investigated on an
experimental test set up developed by conducting open loop and closed loop
frequency response and step response tests. MATLAB Real Time Windows Target
(RTWT) module is used in the tests for application purposes.
| Identifer | oai:union.ndltd.org:METU/oai:etd.lib.metu.edu.tr:http://etd.lib.metu.edu.tr/upload/3/12611090/index.pdf |
| Date | 01 September 2009 |
| Creators | Caliskan, Hakan |
| Contributors | Balkan, Tuna |
| Publisher | METU |
| Source Sets | Middle East Technical Univ. |
| Language | English |
| Detected Language | English |
| Type | M.S. Thesis |
| Format | text/pdf |
| Rights | Access forbidden for 1 year |
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