1. a Division of Production Systems , Department of Mechanical Engineering, Linköping Institute of Technology , S-581 83 Linköping, Sweden E-mail:
2. b Division of Production Systems , Department of Mechanical Engineering, Linköping Institute of Technology , S-581 83 Linköping, Sweden E-mail:
3. c Department of Industrial Engineering and Management , School of Engineering, Jönköping University , S-551 11 Jönköping, Sweden E-mail: