You appear to be conflating random and unpredictable. A double pendulum is not random, in the typical sense, its course is merely unknown. You can be governed by your own purposes and still be unpredictable to someone else, not in the sense that you go out of your way to defy all predictions, but in the sense that such predictions are never totally accurate—the fastest way to find out what a human will do with 100% accuracy is to watch them.
You appear to be conflating random and unpredictable. A double pendulum is not random, in the typical sense, its course is merely unknown. You can be governed by your own purposes and still be unpredictable to someone else, not in the sense that you go out of your way to defy all predictions, but in the sense that such predictions are never totally accurate—the fastest way to find out what a human will do with 100% accuracy is to watch them.