A brisk walk to the finish line
--Around which period did you start finding difficulties in the robot development?
Hirose: We had a hard time getting the robot to walk at the same speed as a human being. In just the first two to three months of development, we managed to get the robot walk as what we dubbed "static walking." But the walking speed of the robot was extremely slow, not even reaching the 1 km/hour-level. Enabling the robot to walk in a "humanoid" manner meant it had to walk briskly at a speed of about 5 km/hour, "dynamic walking" is the word. We finally attained this goal in around 1988-1990; the walking speed of the experimental "E3" model went up to 3 km/hour and the "E4" at 4.7 km/hour. Thus the tough time for us was around period 1986 -1990. During these five or so years, we devoted ourselves in observing how people walked. From time to time, we videotaped and examined people walking and even attached lights on various parts of people's legs to study how their legs were moving when they walked. At times, we visited and questioned orthopedic surgeons on how the human shoulder and pelvis move and how to take rhythms when walking. We even studied people in the context of day-to-day living, watching people walking up and down the stairs of train stations.
--During such period of trial, when did you feel certain that you could make the robot walk?
Hirose: I cannot indicate the exact point in time I felt that kind of certainty. Our R&D approach was to imitate the walking style of human beings. We wrote a computer program on walking style, transplanted the program into a mechanism, and then tried to get the machine to walk. When it fell over, we carefully reviewed what happened and re-programmed the mechanism and it was a repetition of trial and error. And we reached our goal of speeding up the walking speed of the robot to 4.7 km/hour, as a result of these trials. It was not something that we tried and accomplished in a flash.Having said this, I suppose we inked important milestones when we completed the walking mechanism with the "E3" in 1991 and when we developed the technology that prevented the robot from falling over with the "E6." The body was a bit large, but we were proud of the fact that the E6 looked like a robot.In that sense, I felt that we had crossed the finish line when we wrapped up our work on the "E6". Our company is quite extraordinary, though. As soon as we saw our completion of the E6, the top management said, "We told you to make a 'humanoid' robot." Since we had gone to all the troubles of getting the machine to walk on two legs, we were told to give the robot hands and to make these hands move. I was thrilled to hear this. The thought of being able to continue developing the robot made me feel excited. After all, it is great fun. I enjoy working on the robot.