Reconfigurable　modular　robot　is　a　new　aspect　in　the　development　of　robotics.　Compared　with　the　traditional　robots,　a　lot　of　attentions　have　been　paid　to　the　advantages　of　the　reconfigurable　modular　robot,　such　as　the　variety　of　structure　and　the　adaptability　to　the　complicated　environment.　At　present,　most　robotic　control　methods　only　use　the　feedback　of　motor　encoder,　not　use　the　feedback　of　actual　end-position　of　robot　arm.　However,　due　to　the　joint　flexibility　and　integral　assembly　error,　the　control　accuracy　of　robot　arm　is　not　high　only　according　to　the　motor　feedback.　Therefore,　this　control　method　is　the　open-loop　approach.　In　this　study,　a　PowerCube　reconfigurable　modular　robot　system　is　presented　with　motion　simulation　and　control　of　close-loop　real-time　feedback　using　Optotrak3020　measurement　system.　The　mechanical　and　electrical　layout　of　PowerCube　module　robot,　the　robot　motion　model,　the　control　concept　and　implementation　of　close-loop　real-time　feedback　are　investigated　respectively.　Finally,　through　a　3D　simulation　and　experiment　of　modular　robot　arm　for　grasping　a　cup　and　pumping　water,　the　feasibility　and　applicability　of　this　control　strategy　are　verified.　©　2010　IEEE.