Publication: Design of an efficient and flexible pole climbing robot
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Date
2002-03-01
Authors
Chin, Wai Hoong
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Abstract
This thesis is a continuance of a previous project which featured a robot capable
of climbing a cylindrical pole. In this project, the ability of the robot to navigate through
obstacles of various branches on the pole was introduced, and its climbing speed was
increased. To introduce the ability to climb over branches, the motion of the robot was
improved using kinematics design to determine the joints and links required by the robot,
after which, each functional part of the robot was detailed. Tendon driven actuation is
used as the actuator system. This concept enables the arm design to be compact, simple
and versatile. Wheels driven by stepper motors are used to propel the robot up the pole.
This concept eliminates the previous solution of using six discrete steps per cycle for the
climbing motion. As a result, the climbing speed of the robot is increased by nearly 4
times to 2.3m per minute. The geometry of the basic components was designed to be as
simple as possible to facilitate fabrication work. The high strength-to-weight ratio of
aluminium made it ideal as the main material for this climbing robot. The weight of the
robot is 2.52kg with 1.48kg of payload. Calculations were carried out to determine the
torque needed for actuation, which is 1.6Nm for the arms and 0.191Nm for the wheels.
Engineering drawings were prepared using SolidWorks 2001, and a simulation of the
motion was done. The control system implemented in the robot is divided into two
parts,one which controls the arms, and the second which controls the climbing motion. A
force feedback is used for the arm controls. Controls for the climbing motion require
proximity sensors to sense impending obstacles, and a controller which determines its
responses thus enables the robot to be reactive. Lastly, a model of the front auxilliary
body was fabricated to demonstrate the motion of the arms, with a strain gauge to
measure the force exerted on the arm.