A power supply circuit includes a power output port, an operational amplifier, a voltage adjusting circuit, a feedback circuit, and a current controlling circuit. A cross-sectional shape of the pressure chamber may include a circular-arc-shaped side wall portion and linear side wall portions connected with two ends of the circular-arc-shaped side wall portion on the side opposite to the supply side, the distance between the linear side wall portions gradually decreasing toward the side opposite to the supply side. Roller followers engaging with the guide tracks around the guide pins are provided, and the mobile gun arm is made to open or close via the arm holder using a servo motor. Analyzing the article surface feature data can include associating portions of the article surface data with individual features thereby producing associated feature surface data; and analyzing the associated feature surface data. According to the invention, the floor standing area has at least one abrasive surface section, the roughness of which serves to shorten the claws of the poultry walking thereon and to blunt the beaks of the poultry picking thereon.