Mars' Pathfinder Mission

When machines have to autonomously interact with the environment or operate near the optimal set point, we cannot specify all the functions a priori and in a deterministic way. Take, for instance, the Mars Pathfinder mission. It was totally impossible to specify all the possible conditions that the rover Sojourner would face, even if remotely controlled from Earth, so the problem could not be solved by a sequence of instructions determined a priori in JPL's laboratory. The vehicle was given high-level instructions (way points) and was equipped with cameras and laser sensors that would see the terrain. The information from the sensors was analyzed and catalogued in general classes. For each class a procedure was designed to accomplish the goal of moving from point A to point B. This is the type of engineering system of which we will build more and more in the future.

The big difference between the initial machines and Sojourner is that the environment is intrinsically in the loop of the machine function. This brings a very different set of problems, because, as we said earlier, the environment is complex and unpredictable. If our physical model does not capture the essentials of the environment, then errors accumulate over time, and the solution becomes impractical. We thus no longer have the luxury of dictating the rules of the game, as we did in the early machine-building era. It turns out that animals and humans do Sojourner-type tasks effortlessly.

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