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The goal of the paper is to study the properties of a teleoperated mobile machine and produce a simulation model of the machine for later use. In this paper there are introduced a prototype of the teleoperated mobile machine and a simulation model of that machine. The challenge in teleoperation is to have a smooth and accurate control of the machine, because the operator can not feel any force. The machine is valve controlled and because of that the influence of different type of valves can be significant for the control of the machine. By means of the simulation model it is possible to test new components and hydraulic solutions for power transmission of mobile machine. The new computer controlled prototype of the teleoperated mobile machine is electrically controlled with proportional valves has been developed. The simulation model of the machine is verified with the measurements. The goal is that the main properties of computer controlled and teleoperated mobile machine are at least at the same level than in normal mechanically controlled machine, but controllability must be better because of the teleoperation. In this paper there is also introduced the principle of the automatic virtual gearbox. The prototype is equipped with two constant displacement pumps, electrically controlled pressure relief valve and supply pressure and LS pressure sensor. Therefore the information of load pressure is available and supply pressure can be controlled with the rotational speed of diesel engine and pressure relief valve. In teleoperated mobile machine the rotational speed of diesel engine is controlled with electric gas. With these components and a computer control it is possible to set supply pressure level according to the needed load pressure level.

In this paper the torque control properties of a water hydraulic rotary actuator are theoretically and experimentally studied and the results are analyzed and compared with oil hydraulics. If the same performance levels can be achieved with water and oil hydraulics, water as the pressure medium is preferred in applications where external oil leakage is not allowed or applications that take place in fire hazardous environments. The analysis carried out in this paper uses a linear model of the hydraulic drive which is first verified against experimental tests. The linear model allows to study the effect of valve saturation and the effect of using pressure transducers for torque feedback in torque control applications. Two torque control cases are studied: torque control with the boom end in a fixed location and boom end free to move with desired torque set to zero (backdrivable system). Experimental results are presented and compared with simulated results. Results show that in torque control applications, the use of water as the pressure medium does not cause any special control problems and a similar performance than with oil is obtained. Also, pressure sensors can be used for providing torque feedback without causing significant problems.