Line following robots are fundamental platforms in robotics education, yet commercially available solutions remain prohibitively expensive ($150-300$) while lacking integrated obstacle detection capabilities essential for real-world applications. This paper presents LineMaster Pro, an intelligent low-cost line following robot implemented on an Arduino Nano platform that integrates dual TCRT5000 infrared sensors for precision line tracking, an HC-SR04 ultrasonic sensor for real-time obstacle detection, a digitally tuned PID controller with Ziegler-Nichols optimization, and a hierarchical finite state machine for robust obstacle avoidance. A systematic four-phase sensor calibration methodology ensures reliable operation across varying lighting and surface conditions. Experimental validation through 200 controlled trials and 72-hour continuous operation demonstrates mean tracking accuracy of 1.18 cm at 0.4 m/s (95\% CI [1.06, 1.30]), obstacle detection reliability of 96.7\% within 10-40 cm range with 0.7\% false positive rate, and 94\% successful recovery from path deviations. The PID implementation achieves 43\% improvement over conventional on-off control ($p<0.001$). At a total hardware cost of \$28.50 based on verified Bangladesh market prices, LineMaster Pro achieves a 94\% cost reduction compared to commercial alternatives, establishing a practical benchmark for accessible robotics education in resource-constrained environments.

翻译：循线机器人是机器人教育中的基础平台，然而市售解决方案价格依然过高（150-300美元），且缺乏实际应用所需的关键集成障碍物检测功能。本文提出LineMaster Pro，一种基于Arduino Nano平台实现的低成本智能循线机器人。该机器人集成了双TCRT5000红外传感器用于精确线路跟踪、HC-SR04超声波传感器用于实时障碍物检测、经Ziegler-Nichols优化的数字式PID控制器，以及用于鲁棒避障的分层有限状态机。系统化的四阶段传感器标定方法确保了在不同光照和表面条件下的可靠运行。通过200次受控试验和72小时连续运行的实验验证表明：在0.4米/秒速度下平均跟踪精度为1.18厘米（95%置信区间[1.06, 1.30]），在10-40厘米范围内障碍物检测可靠率达96.7%（误报率0.7%），路径偏离后成功恢复率达94%。PID控制实现较传统开关控制性能提升43%（p<0.001）。根据孟加拉国市场验证价格，总硬件成本为28.50美元，相比商业方案实现94%的成本降低，为资源受限环境中的可及性机器人教育建立了实用基准。