Design of a Robocup Rescue Robot Mechanical Sub System

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Shewfelt, Blair
Cram, Benjamin
Remple, Lawrence
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This report outlines the design of the mechanical sub-systems for a rescue robot intending to compete in the Robot Rescue League (RRL) RoboCup competition. After careful consideration of a variety of design concepts, a design with two fixed main drive tracks and four rotating paddle tracks was decided upon. This was the only design that would satisfy the performance and mobility requirements of the competition. The main tracks are fixed along the sides of the robot, and extend the length of the main body section. One paddle track is mounted on each corner of the main drive, and can be rotated 360 degrees about the axis of the input drive shaft. Together, the two main tracks and four paddle tracks provide propulsion to the robot. Following competition requirements, the robot also features a manipulator arm to allow access to shortcuts requiring dexterity tasks. The proposed design measures 1113 [mm] in length with the paddles extended outward, and 594 [mm] when rotated inward. The overall width is 676 [mm], measured from the outer edges of the paddle tracks. The overall height is 319 [mm] with the manipulator stowed, and 571 [mm] with the manipulator extended to its maximum height. The total vehicle weight is estimated at 27.4 [kg]. The center of gravity (CG) is located 20 [mm] rear of the geometric center of the robot body, at a minimum height of 76 [mm], and maximum of 121 [mm], depending on the orientation of the paddles and manipulator. The maximum traversable longitudinal incline was determined to be 82 [º], and lateral incline was 78 [º], with the manipulator stowed. The maximum forward speed is estimated at 80 [m/min] on level ground. The design features two main 250 [W] 24 VDC Maxon 136207 drive motors mated to a 50:1 harmonic drive gear reduction. The harmonic drives are mounted near the front of the frame, with each one driving one side of the robot in a skid-steer configuration. Each paddle track is rotated by a 40 [W] 24 VDC Maxon DCX26L motor mated to a planetary gearbox with a 231:1 reduction. These are […]