The　unknown　payload　will　increase　the　error　of　the　robot　model,　which　will　cause　serious　interference　to　the　collision　detection　and　even　lead　to　algorithm　failure.　Therefore,　a　collision　detection　algorithm　for　robots　working　with　payloads　is　proposed　in　this　paper.　Firstly,　a　novel　torque　observer　with　band-pass　filtering　characteristics　is　designed　based　on　the　generalized　momentum　of　the　robot.　Through　the　analysis　of　the　frequency　domain　characteristics　of　the　robot　dynamics,　the　maximum　frequency　threshold　of　the　robot　dynamics　model　corresponding　to　the　joint　speed　is　obtained,　and　the　parameters　of　the　band-pass　torque　observer　are　determined.　Then,　the　band-pass　torque　observer　is　used　to　filter　the　joint　torque　signal　to　improve　the　tolerance　of　the　collision　detection　algorithm　to　the　robot　model　error.　Finally,　the　effectiveness　of　the　proposed　collision　detection　algorithm　is　further　validated　by　human-robot　interaction　experiments.　The　experimental　results　show　that　the　proposed　algorithm　is　more　robust　than　existing　algorithms,　and　can　meet　the　needs　of　the　robot　with　0~2　kg　unknown　payload.　©　2020,　Science　Press.　All　right　reserved.