In　the　bolt　looseness　detection　task　of　the　locomotive　system,　the　robot　could　be　used　to　highly　improve　the　working　efficiency　and　reliability,　but　faces　the　complex　static　obstacles　while　planning　the　path　for　the　robotic　motion.　In　this　paper,　a　path　optimization　technique　is　proposed　to　obtain　an　optimal　path　with　obstacle　avoidance　for　a　redundant　robot　in　the　static　complicated　environment.　There　are　three　main　contributions　in　this　technique.　The　first　is　the　solving　of　the　inverse　kinematics　problem　for　a　redundant　robot　based　on　the　screw　theory　and　the　geometric　description,　which　is　general　to　all　robots　with　rotational　joints.　The　second　is　the　modeling　of　the　spatial　constraint,　where　the　pseudo　distance　is　defined　based　on　the　plane　description　of　the　obstacles　and　calculated　using　the　spatial　analytic　geometry　knowledge.　The　third　is　the　presentation　of　the　whole　path-planning　framework　based　on　the　above　two　contributions,　which　could　largely　improve　the　generality　of　the　presented　technique.　In　this　framework,　the　minimum-time　path　could　be　obtained　while　guaranteeing　both　the　motion　stability　and　obstacle　avoidance.　Moreover,　a　real　setting　that　includes　an　obstacle　environment　and　an　8-DOF　robot,　is　taken　as　an　example　to　better　present　the　technique.　Finally,　the　simulation　experiment　was　performed　in　Isight　software　to　verify　the　effectiveness　of　the　path　optimization　technique.