Determination of sample size for lifetime test in the inception of robot R&D

The authors have studied for how-to-determine appropriate sample size in the stage of research and development of robot. Due to the cost and time limit, it is almost impossible to proceed to test many prototypes in the real research and development environment. Testing methods for securing reliability should be devised to be handled in an inexpensive way. Several considerations were discussed for that purpose. Especially, Weibull distribution that provides reasonably accurate analysis for reliability was selected and thereby new method responding to the quantitative target of product reliability was developed. Thus, this research is concluded that the generalized equation on sample size determination is helpful to evaluate lifetime in the inception of robot R&D. And the approximated equation can be easily utilized for developing and selecting test method adequate to real test fields. Application study on the establishment of durability test method for robot actuator through parametric ALT was conducted.