Our current testbed is one 42 inches plastic tube with 8 thermisters attached on it. The strand is driven by one NEMA17 stepping motor, which is in turn controlled by a PC through the parallel port. The 8 thermisters are also connected to the same PC through an A/D board. All the algorithms below are based on this testbed, or the simulation of this testbed.
Following is the pictures of the testbed. The black points attached on the white strand are the thermisters, and the metal square tube is the linear actuator.
All the algorithms described below are used to find the maximum temperature gradient alone the strand of the testbed described above. In experiments, we change the temperature distribution by putting a bulb at different place.
We also did some experiments to compare those algorithms. The result of the comparison can be found here .
In decentralized algorithm, we assume that there is no central media for sensors to share the data, but they can communicate with other sensors with a specific range. The algorithms described below will be carried by every sensor simutaneously.