Gantry/Cartesian robot are made up of three prismatic joints. It has 3 degrees of freedom and the axes coincide with Cartesian coordinates. They provide a structure that can be useful for heavy loading situations. They are used commonly for pick and place operations, machine loading, part insertion and stacking part. A gantry is simple to visualize and program and can manipulate large loads for larger working areas, but they occupy lots of space and have a low ration of robot size to operating workspace. The axes are vulnerable to dust and dirt if not protected.
A Cylindrical robot works with a cylindrical coordinate system. It has the ability to reach any point within a specific height and radius. It is usually made up the two prismatic joints and one revolute joint. The revolute joint provides the rotation to access up to a 360 degree rotation and the prismatic joints establish the height and reach of the robot. They are used commonly for pick and place operations, machine loading from pallets and part insertion. Although the cylindrical robot is simple to visualize and program and they can manipulate large loads for larger working areas they can be restricted to areas close to their vertical base and have difficulty going around obstacles.
A spherical robot works with a polar coordinate system. Similar to the cylindrical robot, the spherical robot has the ability for 360 rotations. In addition, spherical robot has an extra revolute joint that gives it the ability to access a spherical area.
A SCARA (Selective Compliance Articulated/Assembly Robot Arm) is a special combination of an articulated robot and a parallel robot. It is comprised of two parallel rotary joints, which enables access up to 360 degrees, but limits vertical movements. SCARA are often used for high speed part insertions, drilling and welding operations and occasionally light to medium load pick and place operations.
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