Integrated technology boosts system functionality

Oct. 17, 2016 – Defining safety rules and regulations in motion control applications is a relatively new concept, with standards only recently being officially defined.

Currently, two specific automation safety standards exist: IEC 61800-5-2 and DIN EN ISO 13849-1:2008, applicable in North America and Europe. Existing within these jumbles of letters and numbers are basic functions and features that must be enabled in the machine to ensure compliance.

However, integrating safety into a motion system presents a much more complicated set of problems than just to equip the machine with the safety protocols and walk away. To illustrate this point, imagine a vertical axis with a substantial load of some sort. Standard safety protocol for an error condition for this type of axis would most likely be safe torque off, halting the linear motion of the axis to allow for error correction. However, if this axis is 20 feet tall and the load is currently at the top, safe torque off turns the now resistance-free load into a significant hazard to operator safety without some sort of external application to latch and restrain the load from falling. In addition, regardless of the number of light curtains, safe stops, and gates a company installs on a machine, there may still be a way for an operator to circumvent the precautions and endanger themselves or others through their actions.

Much of the difficulty in implementing safety in a motion system is thinking outside the box, gathering detailed information about the application and determining the best course of action to maintain safety. Intimate knowledge of the process is vital for discovering areas where standard safety operations may be insufficient to maintain safe operation. In addition, ensuring that machine operators receive proper training and understand the risks involved with operation of the machine is paramount. Implementation of a safe motion system ultimately boils down to a partnership between the integrator and the end users. The collaboration will enable the group to plan for as many possible hazards as possible and ensure safe operation.

Next-generation communication protocols, such as FSoE (Functional Safety over EtherCAT), remove much of the need for additional contacts, safety relays, and other components by connecting directly to the motion components. In addition to streamlining the system, an enhanced communication system such as this allows for much greater precision with sensing of potential hazards, for example noting the presence of an operator within a predetermined range of a light curtain and slowing the machine, rather than stopping the process altogether. Maintaining production processes, even at a reduced speed, will ultimately save the company from lost revenue due to downtime while still keeping their employees safe.

As machines get more powerful, and companies look to maximize throughput and production, motion control safety will need to continue adapting to new challenges in order to ensure the safety of employees. New technologies will remain a significant factor in making these production increases a reality, while still caring for the safety of machine operators.

Matt Prellwitz is the drive technology product specialist at Beckhoff Automation.

This column was originally published in the September 2016 issue of Manufacturing AUTOMATION.