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Importance of detecting obstacles around construction machines increase rapidly. The millimeter-wave radar is the most useful sensor to keep to detect obstacles in the current technologies. because of its good performance under severe conditions. The signal processing algorithm of this radar is developed, for the using in working conditions by means of eliminating signal fluctuations and instabilities caused by its environments. The developed millimeter-wave radar has a reasonable performance, for example, detecting the rear side of automobiles and many types of construction machinery from the distance of 100m.

Small swing-radius hydraulic excavators are often used in narrow construction areas, especially in cities. Operators are required to control the movement of the machine very accurately so as not to damage utility wires, trees, advertising signs, gas lines, underground electric wiring, water mains, and so on. The excavators are designed to warn the operator or stop completely when the machine comes close to a known hazard. To perform this function, the machine must be able to accurately monitor the location of the bucket and boom. Angle sensors are put on the joints of the arms and boom to monitor their angles. The bucket position can be calculated with the sensor outputs. Accuracy and rigidity are the most important features for these sensors. Additionally they must be rugged enough to survive in a severe construction environment. The sensor unit has a potentiometer with +/-0.5% independent linearity.

Electronic control systems using microprocessors for construction machines have been increasing rapidly in response to needs for safety and convenience on the part of operators. Sensors and actuators will play an important role in the proliferation of these systems. Recently, there has been a growing number of applications in which it is necessary to determine the displacement of hydraulic sensors. As a result, many types of sensor systems were developed for this type of application. However, so far there have been no systems capable of working well in construction machines due to these sensors having to be used under extremely severe conditions. Severe impact and high temperature conditions generated by compressed hydraulic oil ended up delaying the development of these systems. In response to these needs, the authors have developed a hydraulic cylinder equipped with a magnetic stroke sensor for use in heavy duty operations.

Preliminary study of a heat insulated diesel engine demanded more than 350°C operating temperature of the cylinder liner temperature at top ring reversal. In order to define the tribological problems of the engine, a single cylinder endurance run was conducted and friction loss of the six cylinder heat insulated engine under operating condition was measured. A major tribological problem of piston ring and liner interface was found to be choosing proper wear resisting coatings for their surfaces as the hydrodynamic film protection at top ring reversal reduced significantly. Considering possible applications to the piston ring and cylinder liner sliding faces, several ceramic coating materials were evaluated for their load carrying capacities and wear resisting properties by laboratory wear test. The results showed that the sliding performances of the coating materials changed considerablly depending on the combination of materials and lubricants.