When industry robots or machine tools works, the working arm or the main shaft should at the exactly right positions with the loads, you use rigid bearings,the positions will not change when the bearings works again.
Since the special design, crossed roller bearings have both linear contact raceway for two load direction roller which crossed the placed. so the BRS www.rigiabearing.com rigid bearings could give 3-4times rigidity than the same size angular contact bearings, then it just use the half room in axial way.