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The articulate or jointed arm robot (or sometime called
Anthropomorphic arms) closely resembles the human arm. The
mechanical structure has at least three rotary joints which
forms a polar coordinate system. The Figure shown an articulate
robot with 6 degree of freedom. The basic three rotary joints
able Arm swap, shoulder swivel and elbow rotations. Additional
3 revolute joints (Roll, Yaw, Pitch) and one prismatic joint
allow the robot to point in many directions, and then reach
out some radial distance.
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| This structure
is very flexible and has the ability to reach over obstructions.
It can generally achieve any position and orientation within
the working envelope. As such articulate robots are used
for a wide range of applications including paint spraying,
arc and spot welding, machine tending, etc. For examples,
the articulate robot allows the welding torch to be manipulated
in almost the same fashion as a human being would manipulate
it. The torch angle and travel angle can be changed to make
good quality welds in all positions. Articulate robots also
allow the arc to weld in areas that are difficult to reach.
In addition, articulate robots are compact and provide the
largest work envelope relative to their size. |
| Typical articulate
robots have five or six free programmable arms or axes.
As mentioned, the flexibility of the articulate robots make
them well suit for a wide variety of industrial application.
But, it is not easy to control. When driving these robots
in their natural co-ordinate system (joint space) the motion
of the robot from one point to another can be difficult
to visualise as the robot will move each joint through the
minimum angle required. This means that the motion of the
tool will not be a straight line. |
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