The design shown below builds upon the previous version by adding an additional control system that controls the proximity, related to the ultrasonic sensor. The proximity control is achieved by changing the goal of the, lower, balance control system. The balance system itself controls its own perception by changing the power applied to the motors. 

The resulting behaviour of the proximity control is that the top section of the leg re-balances in order to maintain the distance between the ultrasonic sensor and the object at a target value (~15cm). 

This system encompasses the same functionality as all previous stages, but extends the functionality with the additional control system. This demonstrates a fundamental principle of the methodology, that the architecture is infinitely scalable; by adding the the modular perceptual control systems.