Experimental implementation of complex path tracking control for large robotic hydraulic excavators

The experimental implementation of the path tracking control of a real hydraulic excavator with an operating weight of 4,500 kg for realising a large hydraulic servo robot with a high loading ability is described in this article. The three working arms are driven by hydraulic valve-controlled cylinders with boom structure systems to achieve rotational motion. Accordingly, the non-linearity of the boom mechanisms, large masses, large dimensions and low natural frequency of the working arms, as well as the coupling influence between the multi-body systems of the three working arms make it difficult to realise high accuracy path tracking control. The control strategy of the model reference adaptive control, which has a simple algorithm and on-line self-tuning ability, is used. Complex path profiles tracking can be achieved by the combination of the path tracking control of the three working arms. Consequently, the large hydraulic excavator can be used as large multi-purpose robots for high loading and high precision applications.