Reducing redesign of safety critical control systems by early risk assessment

Tightening legislation on machine safety, such as the new European Machine Directive that became applicable in Dec 2009, requires that the machine manufacturer has to perform a risk assessment to determine safety requirements. These requirements will result in partial redesign of the control system. In order to reduce this redesign, a risk assessment process utilizing several methodologies for early risk identification is demonstrated. An approach for quantifying system design rework with alternative risk assessment strategies is proposed, in order to enable the collection of data that can be used to rank the redesign impact of alternative strategies.