A deterministic coordinate-based closed-loop robotic manipulator for reliable low-cost pick-and-place automation

Abstract

This study aims to design, fabricate and experimentally validate a low-cost robotic manipulator capable of executing flexible point-to-point pick-and-place operations based on user-defined motion. This study focuses on improving the positioning accuracy and operational reliability of affordable robotic platforms through closed-loop joint control. The proposed system consists of a robotic arm controlled using an Arduino Mega platform and driven by a stepper-servo actuation architecture. Closed-loop joint position feedback was implemented using rotary encoders integrated at each joint, enabling the accurate execution of the commanded end-effector motions. The mechanical design, kinematic modelling, joint-level proportional-integral-derivative control strategy, and experimental procedures for command-based point-to-point motion and pick-and-place tasks are described in detail. The system performance was evaluated through repeated experimental trials using pre-defined motion commands. Experimental results demonstrate that the proposed closed-loop robotic manipulator achieves positioning repeatability within ± 0.2 mm during point-to-point motion. Pick-and-place experiments confirmed the reliable execution of the commanded trajectories, with a grasp success rate exceeding 95% for the representative test objects evaluated in this study. Compared with the baseline open-loop configuration, the proposed closed-loop system exhibited improved motion consistency, enhanced positioning stability, and reduced estimated energy usage during repetitive manipulation tasks, thereby demonstrating the practical advantages of encoder-based feedback control in low-cost robotic applications. In contrast to many existing low-cost robotic manipulation studies that primarily report isolated motion-control performance, the proposed framework provides integrated task-level experimental validation, including positioning repeatability, task success rate, cycle-time stability and energy analysis under repeated operating conditions. This comprehensive evaluation framework improves the practical relevance and experimental reliability of the proposed low-cost robotic system for structured automation environments. This study presents a practical, low-cost robotic manipulation platform that enables accurate command-based pick-and-place operations using a sensor-minimal closed-loop joint control strategy without reliance on vision or force sensing. The experimentally validated design offers a replicable and accessible solution for small-scale industrial automation, laboratory research and educational applications, demonstrating that reliable manipulation performance can be achieved using affordable hardware and simple control strategies.