I am currently attempting to solve the following problem. Say that I have an object that can expand and contract, given some external force. What I want to know is how much it has expanded, or contracted, over time. ( the diameter difference ) In addition, while this expansion or contraction is occurring, the object is free to move around. ( Example, object rolling around on the floor while wearing these sensors on itself )
I am considering of solving this problem by using two sensors, where one lies at the front of the object and one on its complete opposite ( back of the object ). An example of this can be seen below:
When the object expands, here is the size difference:
Obviously, the diameter of the second object is substantially bigger, and it is something I'd like to record as it increases / decreases.
Are there some good sensors that I can use to record this change over time? ( Note, sensors that can attached to a Raspberry pi board, or wirelessly connected to, that is ). I'd also like to stay away from sensors that would easily be lost if movement of the object was introduced, or require cords. ( i.e Capacitance belts, conductive yarns, etc. as they can easily give false readings of "contraction" and "expansion" given that the movement is too large. ex: Capacitative sensor gets stuck on the side of the object, and gives enormous diameter readings )