Recent work in parts handling advocates the investigation of a new generation of devices for parts feeding, sorting, positioning, and assembly. Unlike robot grippers, conveyor belts, or vibratory bowl feeders, these devices generate force fields in which the parts move until they may reach a stable equilibrium pose.
The development of the theory of programmable force fields has yielded a number of strategies to uniquely position and orient parts. Typically, more than one fields are applied in sequence to achieve the desired result. In our IEEE Transactions on Robotics and Automation paper in 2000, we show that unique part poses can be achieved with a single field. In particular, we present a single field that positions and orients any non-symmetric part into two stable equilibrium poses. Then we show that for any laminar part there exists a field in which the non-symmetric part reaches a unique stable equilibrium pose. Our latter result leads to the design of devices that can act as ``universal parts feeders'' proving an earlier conjecture about their existence.
Recent research in the theory of programmable force fields has yielded open-loop strategies to uniquely position, orient, and sort parts. These strategies typically consist of several fields that have to be employed in sequence to achieve a desired final pose. The length of the sequence depends on the complexity of the part.
In our paper, we show that unique part poses can be achieved with just one field. First, we exhibit a single field that positions and orients any laminar part (with the exception of certain symmetric parts) into two stable equilibrium poses. Then we show that for any laminar part there exists a field in which the part reaches a unique stable equilibrium pose (again with the exception of symmetric parts). Our second result leads to the design of ``universal parts feeders'', proving an earlier conjecture about their existence. We argue that universal parts feeders are relatively easy to build.