Precisely positioning pallets in multi-station assembly systems

In multi-station assembly systems, common for mass-customization manufacturing strategies, the product being assembled is held in a fixture attached to a pallet, and the pallet is conveyed between workstations. In high-precision assembly systems, variation in the position of the pallet is one of the largest sources of variation within the error budget, reducing quality and yields. Conventional approaches to locating pallets use pins and bushings, and a method for predicting their repeatability is presented. This paper also presents an exact constraint approach using a split-groove kinematic coupling, which reduces variation in pallet location by an order of magnitude.