This thesis addresses the design, implementation, and verification of safe control of servo motors, with an emphasis on correct positioning, reliable determination of the home position (homing), and the use of the safety functions Safe Torque Off (STO) and Safe Stop 1 (SS1) in combination with hardwired and network-based safety. The central problem tackled by the work is how to ensure repeatable positioning accuracy while simultaneously achieving safe axis stopping under various operating conditions, particularly on vertical and loaded axes where an improper stopping sequence can lead to load drop or mechanical damage. The aim of the thesis is to develop and experimentally validate correct homing execution and the timing coordination of the brake with the safety functions.
The thesis combines a theoretical review of servo control (position, speed, and torque regulation), procedures for determining the home position (reference sensor, encoder index pulse, limit switches), and industrial safety standards with experimental testing on a real system. The tests include comparative scenarios between hardwired and network-based implementations of STO. Analysis of trends and diagnostic logs enables detailed monitoring of servo motor behavior and of the safety functions.
The results show that the correct timing sequence - first engaging the mechanical brake and only then activating STO - reduces the risk of uncontrolled motion and the likelihood of damage to machinery, product, and operators. The SS1 function enables controlled deceleration with lower mechanical stress, although typically with a longer overall time to reach a safe state than immediate STO; the choice therefore depends on the required trade-off between stopping speed and mechanical friendliness. Hardwired safety provides minimal response times and high determinism, whereas network-based safety offers richer diagnostics, greater flexibility, and simpler integration. The thesis concludes with practical guidelines: rigorous execution of correct servo motor positioning, well-considered motion profile settings, and proper coordination of the brake with the safety functions are essential for safe, precise, and reliable operation of servo systems
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