**3.1 Modern trends in autonomous driving systems**

A modern trend in the agriculture is about making farming processes more accurate, efficient, and sustainable with advanced satellite navigation systems (like *Hybrid Steering Systems for Automotive Applications DOI: http://dx.doi.org/10.5772/intechopen.94460*

**Figure 15.** *RTS platform for different complex hybrid servomechanisms.*

GPS) and Information Technology (ITC). Precision Farming is raising the agriculture to a new level: doing the right thing, in the right place, the right way, at the right time in the field. Apart from satellite navigation systems, Precision Farming makes use of a number of other key technologies [15, 16]. They include automated steering systems, which take over specific driving tasks like auto - steering, overhead turning, following field edges and overlapping of rows. On tractors, combine harvesters, maize harvesters and other simulate vehicles there is often a need for electrically actuated steering to make automatic GPS controlled steering possible. In addition, manual steering with variable ratio is an often-wanted feature to improve productivity and driver comfort. For this purpose, Sauer-Danfoss [17, 18] has developed a combined steering unit and electro hydraulic steering valve (**Figures 16–18**) named OSPE: OSP for normal manual steering wheel activated

**Figure 16.** *Hybrid steering module OSPE including both hydromechanical OSP and electrohydraulic proportional servovalve PVE (Sauer Danfoss).*

**Figure 17.** *Hybrid steering system for tractors [17, 18].*

**Figure 18.** *Electrical and mechanical complex pilot operated steering valve [13].*

steering and E for electro hydraulic steering activated by electrical input signal either from GPS or vehicle controller or from steering wheel sensor (SASA) for variable steering ratio. In variable steering mode, the electro hydraulic valve part adds flow to the metered out flow from the steering unit part of the OSPE. This combination has built in safety function in form of cut off valve, which makes unintended steering from Electro hydraulic valve part impossible. So OSPE is the right steering element to build up steering system with very high safety level and so to be able to fulfill legislations demands like e.g. in EU Machinery Directive 2006/42/EC.

*Hybrid Steering Systems for Automotive Applications DOI: http://dx.doi.org/10.5772/intechopen.94460*

#### **Figure 19.** *The driving cabin of a modern tractor.*

On different kind of heavy mobile equipment, as tractors, mobile cranes, selfpropelled modular transporter like Mammoet and dedicated mobile systems like fire trucks there is often need for electrically controlled steering either in the form of a joystick, or fully automatic wireless. For such applications Sauer-Danfoss has developed the pilot operated steering valve type EHPS, which covers a wide range of flows by different geometrical spool flow gain (**Figure 18**).

The above systems turn any tractor in a friendly environment for driver. John Deere [19] gives modern examples of ergonomic cabin of the tractor type 8400R (**Figure 19**).
