Disruption-free software updates in automation systems

Automation systems must primarily be deterministic and reliable, especially in safety-critical environments. With recent trends such as mass customization or Industry 4.0, there is an increasing need for automation systems to be dynamic. Changing parts of the software of today´s automation systems, however, typically requires rebooting the controller, which makes software updates a complex and costly endeavor often despised by operators. This article presents an approach to updating the software of automation systems at runtime without disrupting the system´s operation. This is achieved with a combination of a component-based architecture, cyclic application execution, and a state transfer mechanism between the original and the updated version of a component. We validate our solution with a case study in which we update the control algorithm of a magnetic levitation device running at cycles of 1 kHz without dropping the ball.