Retrofit Kit Design That Converts Industrial Locks into Electromechanical Smart Locks

Abstract

This paper presents the design and development of a modular electromechanical retrofit kit that upgrades traditional quarter-turn mechanical cam locks into secure, digitally controlled smart locking systems. Quarter-turn locks are widely used in school lockers, server cabinets, electrical distribution panels, and industrial enclosures, but they offer limited access control, no auditability, and minimal protection against unauthorized manipulation. The proposed kit addresses these issues by introducing a compact, low-cost electromechanical module that mounts externally without altering the existing lock body. The system uses a 3.3 V DC gear motor controlled by an ATmega48P microcontroller and DRV8837 driver, providing controlled 90° rotation after successful RFID authentication. Optional LED indicators assist the user during operation. To enhance security, the device enforces a temporary self-locking (lockout) period after multiple failed access attempts, increasing security. The retrofit kit’s improvement design enables adaptation to different key geometries, ensuring compatibility with a variety of lock formats. Designed for easy installation, the kit can be mounted within minutes and allows end-users to digitally upgrade their mechanical locks without replacing the mechanical body. Prototype tests confirm system stability, reliable authentication, and low power consumption. Long-term usability is supported by a standard Li-Po battery power supply, achieving an estimated 4500–5000 lock/unlock cycles per 1000 mAh battery charge. The kit is intended as a commercial solution for modernizing physical security infrastructure in industries environments, bridging legacy hardware with modern access control needs.