ABSTRACT
The mobile unit has two independent dr iv ing wheels and a caster wheel. I t uses DC servo motors as actuators. The robot can work continuously at a speed o f 1.5 km/h for about 2 hours on a single charge o f batteries. The l i f t ing unit has a 1,275 m m stroke to elevate the drawing unit and reaches to ceil ing boards up to 3,070 m m height. Because most ceilings in office are about 2,700 mm, the robot can be used at most work construction sites. I t has a telescopic three-stage mechanism composed mainly o f D C servo motor, ball-screw,
and pulley as shown in Figure 21 . The drawing unit is raised up at high speed until the distance between the ceiling and the system is within 150 m m to 200 mm. Then the photoelectric switch fit on the top o f the drawing system turns on, and speed slows to avoid hitting the ceiling. As the drawing unit touches the ceiling, the touch switches are activated and elevation operation ends.
