Parallel Five-Bar SCARA Robot for Expressage Sorting

Overview

The team developed a direct-drive, two-degree-of-freedom five-bar SCARA robot for vision-guided pick-and-place. The project combined mechanical redesign, kinematic modeling, singularity-aware path planning, computer vision, and embedded control.

My contribution

As the mechanical designer, I focused on the structure and end effector:

• Redesigned the linkage using finite-element analysis and maintained a safety factor above 3 under the modeled peak load.
• Moved the four links onto offset height planes after the first design revealed self-collision in simulation.
• Integrated a tendon-driven vertical stroke and a vacuum suction cup for object pickup.
• Supported prototype integration and accurate object-moving tests with the rest of the control team.

Mechanical system

The final geometry uses 180 mm between the two base joints and 135 mm links. Two DJI M6020 direct-drive motors provide actuation, while a Raspberry Pi 4B communicates with the motor controllers over CAN. The end effector uses a servo-driven tendon to compress a spring for vertical motion, with a vacuum pump supplying adhesion.

Team result

The full system detected colored objects from an overhead camera, mapped their coordinates into the robot workspace, and planned paths around singular configurations. In ten recorded pick-and-place trials, the team completed nine successfully; the remaining failure was caused by insufficient vacuum adhesion during a configuration change.