In order to deal with labour shortages due to the predicted low birth rate in the 21st century, and create a more friendly production system, we propose a robotic system which assists production in flexible manufacturing environments. In this robotic system off-line robots are proposed to replace or reduce the need for human workers at the shop-floor. The off-line robots carry out assisting or service tasks for the on-line robots which perform manufacturing tasks at the production line or site. In this paper, first, an analysis of a conventional automatic production system using robots is described. Secondly, the concept of a robotic production system using two types of robots is proposed. Thirdly, a methodology for the realisation of the proposed concept and some technical results are presented. Finally, fault recovery using off-line robots and peripheral technology are discussed.