Efficient PWM-based motor control for educational robotic arm prototypes

Abstract Electrical motor control plays a vital role in robotics and automation, yet its hardware implementation often remain costly and challenging for students and researchers. Commercially available real-time simulators such as OPAL-RT or FPGA-based platforms are powerful but not affordable for common educational purposes. This paper proposes a low-cost and efficient hardware solution for motor control in a lightweight robotic arm prototype, using the Arduino Mega 2560 microcontroller as the central controller. This paper employs pulse-width modulation (PWM) through the Arduino IDE analogWrite() function to achieve precise speed, position, and direction control of multiple motors. The prototype integrates five motors on a single Arduino board: two 188 RPM DC encoder motors at the base and elbow joints, a 50 RPM precision DC motor, an SG90 servo motor, and a 28BYJ stepper motor. This paper proposes different low-cost driver circuits and sensors enable flexible control, including the L293D driver with a 4 × 4 keypad for DC motor actuation, the HC-SR04 ultrasonic sensor for servo positioning, and the ULN2003A driver with IR remote and rotary encoder for the stepper motor. A mathematical analysis of robotic arm kinematics is presented in this paper, which supports the placement of motors at appropriate joints for efficient operation. Experimental validation demonstrates that the proposed setup effectively controls motor speed, position, and direction in real time, providing an efficient and accessible alternative to costly simulators. This paper highlights the potential of low-cost microcontroller-based platforms as practical educational tools for visualizing and implementing motor control in robotic systems.