As a response to the strict government emissions regulations, hybridisation of non-road mobile machinery is required. In this paper, behaviour and efficiency of a hybrid mining loader is studied. The full prototype with implemented DDH (Direct Driven Hydraulics) units had been built; however, its performance was unsatisfactory – a large undershoot and steady-state error of 34 % persisted. Therefore, a new control strategy was suggested to overcome the issues. Performance of the system was enhanced by applying a fuzzy PID controller. As a result, reference tracking was significantly improved compared to the conventional PID control case and steady-state error of 1 % was achieved, while the overall efficiency was kept high in the range of above 50%.

The widespread use of electro-hydraulic (EH) technology of the last decades has led to important improvements in the control features, safety and performance of hydraulic machines. However, limited work exploited the use the EH control features for condition monitoring. This paper proposes a neural network based diagnostic algorithm, that takes advantage of the parameters of a controller developed for the case of an independent metering hydraulic system. The reference application is a truck loading crane available at the authors’ research center. The results show how the proposed methodology is effective to detect faults (the faults considered pertain to the pump, the metering valves and the cylinder), with a limited number of sensors.

This paper focuses on the faulty issues of the independent metering valve (IMV) in mobile applications. First, typical faults are studied in a 2t excavator to analyze their negative influences. The model of the abnormal system is estimated according to the results of fault detection and diagnosis. Accordingly, a fault-tolerance controller is designed to reconfigure normal controller by the coordinate control of other parallel available valves. With the presented fault operation, the dynamic characteristic under reconfigured modes can strictly match with that of faulty system. Simulations are conducted in the excavator to verify the fault-tolerance controller.

In this paper three concepts of double pump supply units are presented and compared to a conventional variable
displacement pump as reference. These supply units consist of two off-the-shelf pumps in a parallel arrangement
and they are meant to perform like a continuously variable source of flow rate. In order to evaluate possible
energy savings of the supply units, their efficiency characteristics are firstly computed in a steady-state
simulation but also examined on a test bench. By means of a semi-synthetic load profile for an exemplary
application, the annual savings of the systems are calculated in comparison to the reference pump. Moreover, a
rating system for the system’s complexity is shown and applied to the three concepts in order to judge the tradeoff
between efficiency and complexity. The studies show that the more complex concepts provide higher saving
potentials than simpler systems, but the interdependence may come unpredictably in some cases.

Hydraulic excavator is widely used in the construction field, due to their small size to power ratio and big
actuation forces. However, due to large throttling loss and gravitational potential wasting, its energy efficiency is
very low, which is even lower than 10%. This paper aims to improve the energy efficiency of the hydraulic
excavator by reducing throttling loss and regenerating potential energy directly based on a novel pump
controlled system. The system under consideration utilizes a newly designed asymmetric pump which has three
ports, the two are connected to the hydraulic cylinder, the other is connected to an accumulator. Thus, this
system can regenerate the potential energy directly and can match the unequal flow rates of the single rod
cylinder basically. Furthermore, working performances of the excavator boom system with the asymmetric pump
and independent metering circuit are studied comparatively. Results show that, compared with an independent
metering circuit, the electric power consumption during the boom going up can be reduced by 56%.