Digital Twin-Based Design and Validation of a Collaborative Robotic Cell for Automated Chocolate-Bar Unwrapping

Abstract

This paper presents the design, simulation, and validation of a hybrid automated workstation for unwrapping chocolate bars, migrating from a highly variable two-operator manual process to an optimized single-operator human–robot collaborative cell. Using a digital twin methodology, the system was evaluated across two complementary platforms: Process Simulate, for kinematic path planning and collision analysis, and Plant Simulation, for discrete-event throughput analysis. The automated cell integrates a five-axis UFactory xArm 5 robotic arm fitted with a custom three-finger gripper that performs a specialized "snap-and-slide" extraction sequence, together with a gravity-fed sorting hopper, an infrared proximity sensor for object detection, a FLIR A35 thermal-imaging camera for automated rejection of heat-softened bars, and an SMC ZH10DS vacuum-assisted waste-disposal unit. Kinematic validation in Process Simulate confirmed collision-free trajectories and a cycle time of 9.6 s per bar, a 20% improvement over the 12 s manual baseline. Plant Simulation runs over a 30-minute production window demonstrated system resilience under varying defect rates, yielding 47, 44, and 38 finished units for low (10%), medium (15%), and high (20%) rejection scenarios, respectively, while the nominal baseline run produced 350 units against the target KPI. The resulting design reduces direct labor requirements by 50%, removes repetitive-motion ergonomic risk, and provides a validated, scalable automation blueprint for future production growth.