Free-space　detection　is　considered　as　one　of　the　most　important　tasks　in　intelligent　vehicle,　which　remains　the　essential　requirement　for　obstacle　detection　and　path　planning.　As　a　part　of　Internet　of　Things,　vehicle-based　device　produces　a　large　amount　of　data　requiring　to　be　processed　in　real-time.　Therefore,　this　study　proposes　a　fast　free-space　detection　system　with　a　mobile　platform　based　stereo　vision.　The　current　system　processes　the　image-based　perception　signal　in　terminal　equipment,　which　avoids　lots　of　data　transmissions　between　cloud　and　vehicle.　In　terms　of　flexibility　and　robustness,　a　fast　spare　disparity　matching　algorithm　is　suggested　to　be　real-timely　processed　in　a　low-power　mobile　platform.　Based　on　the　spare　disparity　map,　the　current　work　improves　the　u-disparity　space　algorithm　as　the　u-log-disparity　space　with　the　aim　to　detect　the　free-space　for　significantly　lowering　the　running　time.　Besides,　we　also　provide　a　complete　system　design　including　hardware　and　software.　The　experiments　demonstrate　that　our　system　is　precise　and　robust　under　complex　real-time　driving　environment.　©　2021　Elsevier　B.V.