A Gas-rate Gyro Comprising Just Eight Parts

The gas-rate gyro that led to the development of a practical navigation system for cars

<< 1. Behind the Success of the CVCC Engine
<< 2. Creating a Progressive Strategy
<< 3. A Gas-rate Gyro Comprising Just Eight Parts
<< 4. Gyrocator Development: A Path Strewn with Difficulties
<< 5. Could the Map Be Wrong?
<< 6. The Final Test: From Suzuka to Tokyo
<< 7. The Challenge of Digitization
<< 8. "A System That Cannot Lie"
<< 9. Analog to Digital: A Three-year Detour Leads to the Goal

Kume had a chance to visit a training site used by Japan's Self-defense Force. Watching a group of tanks rumble across very rough terrain, Kume suddenly noticed their gun barrels. Regardless of the attitude of the tank itself, the barrel was able to maintain constant aim with respect to its target. Kume, who was later told that the barrel was controlled by a gyroscope(Note 1*), thought of adapting that technology for use in cars. Upon returning to the R&D Center, he gave the order to study gyroscopics.

Having heard of Kume's idea, Tagami believed the technology could be applied to suspensions, but that notion was dispelled when he got hold of a gyroscope and disassembled it. Not only was a gyro a result of precision engineering, it had more than 200 parts. Obviously, it was something that could be adapted to mass-produced cars. However, some new form of technology was needed in order that Tagami's electrical/electronics strategy might come to life. Tagami persisted choosing not to give up on the gyroscope, leading him to the gas-rate gyro.

The gas-rate gyro works by using the inertial force of gas to move straight, employing helium ejected from a nozzle and blown onto two heated wires. The unit determines directional changes by sensing the temperature differences between the two wires. Therefore, this type of gyro, which employed just eight parts, was a very appealing candidate. However, it was not very accurate, and the zero point was often impossible to locate precisely. It was a problem for the development staff, but further study nevertheless identified certain benefits. As a result, the staff continued its research, hoping to develop a system that would offer reliable control, although within a limited range, along with constant zero correction.

The team's research in gyroscopics took a new turn in 1977, when a staff member proposed that the system might be utilized for travel-route guidance. The suggestion was that the gyro's direction-sensing function could be used to guide a car if zero was constantly adjusted to the target road.

The team began experimenting immediately. First, a map was drawn on a transparent sheet, then the target route was traced using a black, felt-tip marker. The objective of their experiment was to confirm whether the sensor could follow the route and guide the car. In fact, their initial results were highly encouraging. Subsequent experiments examined a more advanced idea, attempting to determine whether the sensor could pinpoint its own location according to road patterns and the car's direction of travel. This indeed became the starting point for important research, eventually leading to the world's first automotive navigation system: the Honda Electro Gyrocator.

Note 1* Gyroscope: A device consisting of a Spinning wheel mounted on a base so that it can rotate freely in the three axes.
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