-The paper addresses a typical application of the hydrostatic transmissions, i.e. the locomotion of vehicles. It is proved that if a full traction scheme is adopted (with hydraulic motors on both axles) the contribution of the front and rear axle to the overall traction capacity can be changed by acting on the displacement setting of the individual motors. By piloting these degrees of freedom through an automatic control system, the perturbations in the traction balance due to soil properties or vehicle attitude can be compensated.Index Terms -fluid power, hydrostatic transmission, modelling and simulation, traction control.
Fully automated agricultural field treatments and Precise Farming are coming in shortly; yet increasing production needs demand a more efficient, planned and harmonized interaction between the machinery clusters involved in the work session. Soon a strong, effective and integrated standardization will be more than needed. This is the path the ISO standardization working group ISO TC-127/SC19/WG5 has taken. The paper describes the further enhancements done from previous works [1,2]. Particularly, we focused on stabilizing performances of high priority communications at the expense of best-effort, low urgency traffic. Performances are explained as [2]. The main improvements concern some kernel modifications, especially about the networking management. The results will show significant steps forward towards a quasi-isochronous transport protocol that manages high priority flows ensuring a high level of determinism and throughput.
The metering out sensing system represents the latest, and most promising, architectural concept for improving the performance of mobile multiple actuation systems through hydraulic proportional components control.
The first part of the paper introduces the novel architecture of meter-out sensing control system, properly designed to distribute the flow rate directed to actuators according to the proportional control of the metering out element only. To do this, an innovative piloting subsystem controls the pump displacement, while a set of compensated proportional control valves applied to actuators outlet work to manage the load unbalance. The inlet doesn’t have any proportional throttle element thus reducing control losses with respect to state-of-the-art systems. In this way, the architecture is able to control both resisting and overrunning loads, and its design could easily include the automatic activation of the regenerative function to limit the requested hydraulic power.
Then, the paper highlights how the proposed architecture of meter-out sensing system, which does not require complex sensor networks or complex electronic controls, could overcome the most important limitations affecting other control technologies currently adopted in mobile hydraulics.
The third part of the paper depicts the main results obtained in the evaluation of the performance figures of merit for the metering out sensing system, performed through a Virtual Test Procedure applied to a lumped and distributed parameter numerical model.
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