Many natural structures change shape whilst retaining function as a reaction to on outside stimulus. One of the well-known examples is the giraffe’s neck that reaches out to tall trees for food. This interesting motion, triggered by a hunger impulse, helps the giraffe survive in the savannas. Similar types of man-made kinematic structures that react to outside driving forces are essential in the development of more efficient structural systems. Imagine an umbrella canopy that folds down under increasing wind loads when its deployed stability is at risk. Or even better an umbrella that unfolds when it senses the sun’s heat. A wind turbine mast that adjusts its height depending upon the location of the wind. To investigate the potentail of these smart structures, we built a smart mast.
The smart mast is an active pantograph tower provided with heat sensors, a control system and an actuator. The analogy with the human body is the nervous system: a closed loop system of sensation (sensors-action of afferent neurons), decision (control system-action of interneurons), and reactions (actuator-efferent neurons) An outside stimulus (either pressure or heat pressure) sensed by the fibre optic sensors located at distinct locations on the mast triggers an algorithm in the control system. The control system sends a signal to the actuator to respond and adjust the structure to a tower’s shape more suited to the sensed stimulus. The tower consists of three tiers of 3 levels of pin jointed pantographs. One single actuator placed between the two extremities of one of the bottom pantographs drives the 3D motion of the structure.
We would like to thank the following students to make this experiment possible Peter Szerzo, Sabrina Siu, Thomas Mbise, Lehman Garrison, Meghan Krupka. And we would like to thank Joe Vocaturo for his excellent and always appreciated craftmanship.
You can see the mast at work on http://www.youtube.com/watch?v=mNszIzQ2L9g
This project is the resultt of close collabortion between the Form Finding and Structural Health Monitoring Lab at PU.