For　nonlinear　system　subject　to　unknown　control　direction　caused　by　input　backlash,　an　adaptive　command-filtered　control　strategy　is　presented　in　this　work.　The　proposed　control　method　not　only　overcomes　＇computational　complexity　explosion＇　inherent　in　traditional　backstepping　method,　but　also　guarantees　rapid　convergence　of　tracking　error.　Meanwhile,　a　salient　characteristic　of　command-filtering　error　is　that　the　finite　convergence　time　is　assigned　in　a　prior,　which　is　proved　by　Lyapunov　stability　method.　Especially,　unknown　control　gain　caused　by　input　backlash　of　controlled　system　is　handled　by　Nussbaum-type　function.　Finally,　simulation　analysis　and　experimental　case　illustrate　the　feasibility　and　effectiveness　of　proposed　control　scheme.　©　2024　European　Control　Association