Since the introduction of electronic actuated valves, the demands for application oriented machine functions in the field of agricultural and construction machinery has continuously grown. As a result of this, the automation of mobile hydraulic systems has gained relevancy. Presently, mobile hydraulic driven machines are mainly controlled open-loop, which has significant deficits like inadequate dynamic behavior (e.g. accuracy), movement dysfunctions in case of pump saturation, movement behaviour depending on parameters e.g. temperature, load etc. This leads to additional strain for the operator, due to the necessary counter measures that have to be taken during operation. The objective of this project is to improve the situation as mentioned above by developing and implementing a closed-loop controller concept with the help of position and velocity sensors, which are integrated in the cylinder drives. With regard to safety and strain for the machine operator further possibilities yield the implementation of additional assistance functions which support the operator like software-based end position damping, flexible workspace limitation. Due to these measures the efficiency, safety and dynamics of the mobile working machine can be increased and the strain for the operator reduced. The measures as mentioned above, were developed and implemented on two systems separately. The stationary front-end loader test rig consists of a load-sensing hydraulic system with electro-hydraulic controlled valves and a front-end loader. The measuring and control system is made up of a PC, dSPACE Autobox and additional sensors. The cylinder drives are equipped with sensors which measure position and velocity of the piston relative to the cylinder housing. A rocker can be used to induce pushing and pulling loads on the implement of the front-end loader. The tractor depicted is a series tractor equipped with a conventional front-end loader. The cylinder drives are similar to those of the test facility and are equipped with the same sensors. The implementation of a closed-loop controller for velocity controlled cylinder drives shows a significant improvement regarding stationary accuracy and effects regarding parameter such as temperature and load pressure. With respect to mobile working machines, the introduced system can aid the development of automated movement procedures of frequently repeating processes. With respect to assistance systems, the end position damping function and workspace limitation function increase the durability and safety of mobile machines. Due to the fact that the developed assistance functions are software based, the functions are easily portable from one mobile machine to another. A further step with regard to workspace limitation may be the introduction of sensors which measure declination of the mobile machinery. With this additional information, the accuracy of the workspace limitation can be increased.


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    Title :

    Assistance functions in mobile hydraulics with controlled cylinder drives


    Additional title:

    Geregelte Zylinderantriebe mit zusätzlichen Assistenzfunktionen


    Contributors:


    Publication date :

    2008


    Size :

    11 Seiten, 10 Bilder, 3 Quellen


    Type of media :

    Conference paper


    Type of material :

    Print


    Language :

    English




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