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Operations involving excavation of bedrock in large-scale civil engineering projects, or quarrying works for limestone or crushed rock can be broadly divided into two methods: blasting, and excavation using mechanical power. Ripping operation using bulldozers is typical example of the second method, and this method is superior because it is safe and does not cause pollutions. For this reason, its applicable range is being expanded including areas where the blasting method was being used. However, ripping operation using bulldozers demands a high level of training from the operator, and in addition to this, shoe slippage causes premature wear of the undercarriage and low fuel economy. The shoe slip control system that we have developed carries out sensing of the acceleration of the machine in forward and reverse directions, and sensing of the input / output speed of the torque converter, and in this way it always knows the traction and the slip ratio of the machine.

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.

Unmanned off-highway dump trucks have been developed as the first step toward entire mine automation. The vehicles are operated on a teaching-playback basis. That is, an operator once drives a truck along a desired path, which is stored in IC memories as a series of points. Then microprocessors control the car so that it runs on the route repeatedly. The data can be saved in IC cards. System supervisors can select any one course in a card set on board. The card can be detached and kept for the future use. Also it can be copied to spread the course data to other vehicles when multiple trucks are operated in a fleet. When a vehicle is inside a loading area, an operator of a loading machine can drive the truck by radio control so that the operator can stop the truck at any point where he/she wants to load. The entire system comprises several chief subsystems, man machine interface including radio control, navigation, vehicle control, data link, and safety unit.

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.

KOMATSU has successfully developed and marketed the HYPER GX series computer-controlled, intelligent hydraulic excavators. The development concepts of the HYPER GX series are as follows: 1. To improve safety at construction sites by use of measuring functions which reduce the number of ancillary workers. 2. To improve working environment and the quality of work by use of automatic functions which reduce operator fatigue and time required to complete a job. 3. To solve the problem of shortage of experienced workers by the use of operator support functions which allow easy operation even for inexperienced or older operators. Representative of these is the fully automatic grading function, with which the movement of boom, arm and bucket is computer-controlled to enable automatic excavation at a predetermined gradient.

The paper provides mechanical and performance specifications for a giant 650 PS bulldozer and cites the outstanding features of this machine. The new bulldozer offers improvements in dozing, ripping, and pushing. It has an electropneumatic system employing solenoid valves and air cylinders, and it can be controlled by radio for unmanned operation in dangerous sites.

The only way to operate a construction machine efficiently is to improve the cost effectiveness. First, it is necessary to clarify the policy regarding owning and operating costs which directly concern cost effectiveness, and the location and standards for measuring reliability and maintenance activities which we face in connection with cost effectiveness. Next, it is important to have efficient maintenance support activities to improve the mechanical availability for the customer. However, for the customer, the support activity most concerned with maximizing profit is not simply maintenance problems. It is necessary to have support activities which go back to the source of the user's implementation processes. We would like to introduce what kind of systems are available for these support systems, and as it is now impossible to operate the systems without using the power of computers, we would like to give examples of comprehensive systems using hardware and software.

The four models of the new PC-Series hydraulic excavators, the PC200-3, PC220-3, PC300-3, and PC400-3, ranging from 18-ton to 40-ton capacity, were brought to the market in 1984, and they have been highly appreciated by the customers for their stability and performance. During the developing stage of these new models, we thoroughly researched and analyzed how hydraulic excavators had been used under various working conditions in order to grasp the qualities which the customer's demand. To realize those qualities, we effectively used mechatronic technology in addition to our unique technologies. The results of the above are the electronic OLSS equipped with a mode changeover mechanism, an automatic decelerating system, a new hydraulic system, etc., which lower fuel consumption, increase workability, lower noise, and improve driveability. In addition, the appearance of each model is improved, and many features including the new monitoring system have been installed.