Vibration damping in mobile machines using pressure feedback
Perälä, Jarkko (2017)
2017
Automaatiotekniikka
Teknisten tieteiden tiedekunta - Faculty of Engineering Sciences
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Hyväksymispäivämäärä
2017-12-07
Julkaisun pysyvä osoite on
https://urn.fi/URN:NBN:fi:tty-201711222196
https://urn.fi/URN:NBN:fi:tty-201711222196
Tiivistelmä
In this thesis a hydraulically driven wheel loader, which has a flexible crane mounted in front of the machine, has been under research. Flexible boom was excited with a operator given commands, which caused the system vibrate due to different sources of flexibility. The goal was to test cylinder load pressure as a estimate of boom vibrations and use it as a feedback signal to suppress the system oscillations. Therefore, a simulation of wheel loader was created, which replicates real four wheel loader located at the facilities of Laboratory of Automation and Hydraulics.
The first simulator represents a traditional hydraulical system, which has proportional directional valves and variable displacement pump with load sensing functions. A simple controller with pressure feedback vibration damping was designed and tested with different scenarios. After promising results, another simulator was created, which emulates the existing wheel loader better. This experimental wheel loader, called as IHA-machine, has different directional valves and pump operating principal. For working hydraulics, a digital flow control unit was installed. As a power source, IHA-machine has a variable displacement pump-motor, which has a possibility to collect energy from hydraulic system.
Updated simulation version was tested with a controller, which was able to control flow and supply pressure. Vibration damping was added to the flow controller and tested in simulator. After this, the same controller was also tested in real IHA-machine. The results showed, that load pressure as an estimate of system vibrations is a promising way to damping the oscillations that exist in the application. However, the simulation results couldn't be repeated at the same level in the real machine. The control of boom with flow in digital valve environment appeared to be a difficult task when vibration damping was implemented. Regardless, some oscillation canceling was still achieved.
The first simulator represents a traditional hydraulical system, which has proportional directional valves and variable displacement pump with load sensing functions. A simple controller with pressure feedback vibration damping was designed and tested with different scenarios. After promising results, another simulator was created, which emulates the existing wheel loader better. This experimental wheel loader, called as IHA-machine, has different directional valves and pump operating principal. For working hydraulics, a digital flow control unit was installed. As a power source, IHA-machine has a variable displacement pump-motor, which has a possibility to collect energy from hydraulic system.
Updated simulation version was tested with a controller, which was able to control flow and supply pressure. Vibration damping was added to the flow controller and tested in simulator. After this, the same controller was also tested in real IHA-machine. The results showed, that load pressure as an estimate of system vibrations is a promising way to damping the oscillations that exist in the application. However, the simulation results couldn't be repeated at the same level in the real machine. The control of boom with flow in digital valve environment appeared to be a difficult task when vibration damping was implemented. Regardless, some oscillation canceling was still achieved.