Surgical lighting in motion: Design and validation of an improved suspension mechanism for the surgical luminaire

Surgical lighting in motion: Design and validation of an improved suspension mechanism for the surgical luminaire

Harms, J.J.

Dankelman, J. (mentor)
Knulst, A.J. (mentor)

Mechanical, Maritime and Materials Engineering

BioMechanical Engineering

BME

2012-06-07

Usability issues have been observed in luminaire repositioning, during surgical operations. These difficulties were confirmed to be related to the kinematics of the translational subsystem of the suspension mechanism, specifically the possibility of singularity. Due to which the required force for luminaire repositioning depends on the spatial arrangement of the mechanism. Based on these findings, the goal of this research is to design a surgical luminaire suspension system that improves luminaire repositioning. With the hypothesis that a suspension mechanism without the possibility of singularity will improve luminaire repositioning. Within this research framework, the task was specified to the design of a passive serial suspension mechanism for the surgical luminaire that improves luminaire repositioning and can be easily actuated. This design project exists of two parts, a conceptual design process and a validation of the design. Based on a function analysis of the suspension it was chosen to focus the conceptual design process on the translational subsystem of the suspension. A computer aided method was devised to optimise the mechanism kinematics to the required movement space in the operating room. Which resulted in 13900 serial combination of revolute joints, prismatic joints and links. Based on a scoring routine, a selection of concepts was made and further assessed. The resulting design is an adaptation of the translational subsystem of the conventional suspension mechanism and is considered most feasible. The adaptations consist of a rail system from which the mechanism is suspended and a wrapping pair that couples the two vertical rotations of the pendant-type mechanism. As a result, the horizontal movement space is described without singularity and the movement space is improved. To validate the design and test the hypothesis, a full scale prototype has been build and tested in a user experiment with 14 participants. The prototype is based on a donated conventional suspension system that is adapted to easily switch between the (new) coupled state and the (conventional) uncoupled state. All participants completed an equal movement sequence in both states, thus creating paired measurements of input forces and the position of the mechanism’s end-effector. Based on the consistency in work between opposite movements in one state it was determined that the movement forces in the new design are indeed independent of spatial arrangement, whereas the reverse is true for the uncoupled state. Further analysis between states shows significant improvement in movement duration, work and jerk cost for the coupled mechanism. Also, qualitative data collected during the experiment show that participants significantly favour the coupled mechanism. With these results it can be concluded that the hypothesis is valid and that the research goal has been accomplished.

surgical lighting
luminaire
suspension mechanism
design
validation

http://resolver.tudelft.nl/uuid:8c28f1ac-9d13-47e8-ac85-f3acd6fbc9a5

2013-06-07

Student theses

master thesis

(c) 2012 Harms, J.J.