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Purpose A frequently mentioned lack of teleoperated surgical robots is the lack of haptic feedback. Haptics are not only able to mirror force information from the situs, but also to provide spatial guidance according to a surgical plan. However, superposition of the two haptic information can lead to overlapping and masking of the feedback and guidance forces. This study investigates different approaches toward a combination of both information and investigates effects on system usability. Methods Preliminary studies are conducted to define parameters for two main experiments. The two main experiments constitute simulated surgical interventions where haptic guidance as well as haptic feedback provide information for the surgeon. The first main experiment considers drilling for pedicle screw placements, while the second main experiment refers to three-dimensional milling tasks such as during partial knee replacements or craniectomies. For both experiments, different guidance modes in combination with haptic feedback are evaluated regarding effectiveness (e.g., distance to target depth), efficiency and user satisfaction (e.g., detectability of discrepancies in case of technical guidance error). Results Regarding pedicle screw placements a combination of a peripheral visual signal and a vibration constitutes a good compromise regarding distance to target depth and detectability of discrepancies. For milling tasks, trajectory guidance is able to improve efficiency and user satisfaction (e.g., perceived workload), while boundary constraints improve effectiveness. If, assistance cannot be offered in all degrees of freedom (e.g., craniectomies), a visual substitution of the haptic force feedback shows the best results, though participants prefer using haptic force feedback. Conclusion Our results suggest that in case haptic feedback and haptic assistance are combined appropriately, benefits of both haptic modalities can be exploited. Thereby, capabilities of the human-machine system are improved compared to usage of exclusively one of the haptic information.Publisher's Note Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations.

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Paramedics perform physically demanding tasks during patient transport in daily routine and therefore suffer more often from musculoskeletal ailments, mainly low back pain, than any other profession. We hypothesise, that current transport aids do not offer sufficient support when it comes to obstacles and stairs during patient transport. Therefore we conducted an Ovako Working Posture Analysing System (OWAS) field study to capture postural workloads during patient transport and connected the results to a survey among paramedics about occurring obstacles. The results of the OWAS analysis showed strenuous working conditions during barrier-free transport with classical transport aids, like stretcher and stretcher chair, but enormous postural workloads when barriers occurred. Our survey revealed, that stairs occurred in 38 %, and at least one barrier, like narrow passages, curbs, etc., in 48.1 % of all deployments (n=405), we can quantitatively link postural workloads with occurring obstacles. In conclusion, there is a high demand for ergonomic improvements of current transport aids and a high potential of active assist devices to reduce harmful loads on paramedics.

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