An automatic truck unloader for unloading/unpacking product, such as boxes or cases, from trailers and containers is disclosed. In one embodiment, a mobile base structure provides a support framework for a drive subassembly, conveyance subassembly, an industrial robot, a distance measurement subassembly, and a control subassembly. Under the operation of the control subassembly, an industrial robot having a suction cup-based gripper arm selectively removes boxes from the trailer and places the boxes on a powered transportation path. The control subassembly coordinates the selective articulated movement of the industrial robot and the activation of the drive subassembly based upon the distance measurement subassembly detecting objects, including boxes, within a detection space, and dimensions of the trailer provided to the control subassembly.