An Investigation of the Measurement of Transient Contacts in Human-Robot Interaction

The collaborative robot safety mode 'power and force limiting' requires the compliance of biomechanical limits to ensure human safety. As part of the risk assessment, it is common to test possible contact points of a collaborative application for a) quasi-static contact (e.g. squeezing or clamping) and b) transient contact (collision with free impact). Although, there are standardized power and force measuring devices (PFMD), which are offered by different companies on the market, multiple, partly differing measuring methods exist. Especially for the transient contact, the respective measuring setup is not consistently defined. Therefore, we carried out an investigation of three state-of-the-art measurement approaches for transient contacts: i) fixed measuring device, ii) linear moveable device on a sledge and iii) device on a pendulum. For a reproducible comparison, we first compared them on an analytical and an experimental perspective. Furthermore, we addressed the specific requirements of cobot applications within flexibleworking systems. Finally, we analyzed and interpreted the results to derive recommendations for the selection of the measurement setup of the transient contact.