The system is billed as the first technology in the world that ties the brake system in with satellite navigation. The new system will alert the driver to an upcoming stop sign, and then when it decides the driver has approached at too high a speed or is too close to stop with the currently applied brake force, the computer will take over and stop the vehicle. The stop-sign information is contained in the map data built into the system.
Given the nature of the satellite-based GPS system, inaccuracy can be chased down to within a foot (30cm) on the most high-end systems. For systems more like those installed in cars, however, the inaccuracy can be as much as 50ft (15m), especially when moving in relation to a stationary object. Add in the potential for stop sign locations to change or be converted to stop lights, and the possibility for erroneous brake application seems high enough to make anyone nervous about buying such a system. It certainly wouldn't be the first time a GPS system had led an overly-reliant driver astray.
Toyota claims the system will be 'smart' about the use of the brakes, adjusting them based on both the GPS information and the data taken from a rear-mounted camera. The new system will be launched on new models in Japan in the near future, which would indicate Toyota has done its homework and thinks it can safely bring the technology to market.
As drivers and car enthusiasts, we have to wonder how much this sort of technology will actually help drivers avoid accidents and how much it will instead encourage (even further) decreased attention. After all, why bother paying attention to road signs and intersections if the car will stop you anyway? That's just time wasted that you could be reading the morning news or applying makeup. Or eating. Or talking on the phone. Or all of the above.