The problem of misalignment of assembly tasks using robots is well known. The problem can be discussed in a base form as inserting a peg into a hole. Using this principal many active and passive sensing systems have been developed. Apart from vision systems, which are relatively expensive, the majority of the systems utilise the contact forces between the two mating parts in order to reposition the arm, or compensate for positional error.
This paper will discuss the development of a low cost non contact sensing system for peg in hole assembly. The sensor uses the back pressure from a pneumatic transducer to define three points on the holes circumference, these points are then fed back to the robots controller, to compute the exact centre position. Thus alignment of the peg is assured.