Analysis of a SCARA Robot for Pick and Place under a Kinematic Constraint

Abstract

The Selective Compliance Assembly Robot Arm (SCARA) robots are extensively utilized for assembling electronic products like PCBs for TVs, mobile phones etc. These robots operate at very high speeds. The SCARA configuration has the main advantage of gravitational load, Coriolis, and centrifugal forces not stressing the structure as much as with a robot with the axes horizontal. This feature is important at high speeds and for high precision and it provides high stiffness to the arm in the vertical direction, and high compliance in the horizontal plane. Thus this configuration is advantageous in the tasks involving assembly. In this paper, a SCARA robot is modeled using the commercial CAD software. Equations are presented for direct and inverse kinematics for a pick and place operation. The robot is used to pick a mechanical part/assembly from a conveyor and place it on a machine being serviced by the SCARA robot. Results of angular rotations, velocities, acceleration of joints and positions of the end effector are presented. Importance of positioning of the different members of a SCARA robot is highlighted.