Summary: ``Robots with kinematical redundancy under pseudoinverse control exhibit undesirable chaotic joint motion, which leads to erratic behavior. In this study, we use a delayed feedback method to control chaotic motions of a planar 3R rigid and a planar 3R flexible redundant robot under pseudoinverse control when the end-effector traces a closed-path repeatedly in the work space. It is demonstrated that chaotic motions of robots with kinematical redundancy can be turned into regular motion when the delayed feedback method is applied with some appropriate parameters. This study provides new insight which is helpful in solving the repeatability problem for redundant manipulators.''