PROBLEM TO BE SOLVED: To provide an ascent/descent control unit for a farm working machine, which is constituted so that an ascent/descent driving mechanism for the working machine ascendably/descendably connected to a traveling machine body can be subjected to operation control based on the detected information on the height of the working machine from the ground so as to keep the height of the working machine from the ground at a set height, and which enables an ascent/descent operation by suitably responding to even a sharp fluctuation in the height of the working machine.SOLUTION: A detected value &theta from a height detecting means for detecting the height of the working machine from the ground, and a variable speed &omega, which is obtained by differentiating the detected value &theta, serve as information on the height of the working machine from the ground, which is used for controlling of the operation of the ascent/descent driving mechanism 5.COPYRIGHT: (C)2008,JPO&INPIT【課題】 走行機体に昇降自在に連結した作業装置の昇降駆動機構を、検出された対地高さ情報に基づいて作動制御して、作業装置の対地高さを設定高さに維持するように構成した農作業機の昇降制御装置において、作業装置の急激な高さ変動に対しても好適に応答して昇降作動を行わせることができるようにする。【解決手段】 作業装置の対地高さを検出する高さ検出手段からの検出値θと、この検出値θを微分して得られる変化速度ωとを、昇降駆動機構5を作動制御する対地高さ情報としてある。【選択図】 図2
