A Conformal, Optimized 3D Printed Kneepad With Deformation Sensing

Abstract

Additive manufactured smart wearables are establishing an increasingly firm foothold within the monitoring of physical activities. A tiler was the use case proposed by this study, which seeks to monitor changes in their typically kneeling work position with the goal of tracking behaviour and alleviating long-term damage due to incorrect posture. This paper has described the development process of a conformal kneepad with embedded sensing, obtained by means of interposing flexible tactile sensors between 3D printed elastomeric layers. Topology optimization is employed towards material reduction in the context of tailoring the kneepad design for the differentiated loading which the case study imposes. Considerations on the inherent challenges of overmolding flexible geometries are provided along with a design-to-fabrication process description which visits 3D printing, post-processing and 3D scanning. The use of the latter enables the creation of a fully conformal design, optimized for the perfect fit on each individual wearing the kneepad. The topology optimization is validated numerically and the ability of the kneepad to react to different pressure stimuli is tested with a robot arm, capable of simulating different contact angles and load cases. By means of dedicated electronics, the sensed information is modulestreamed over WiFi and tactile images are formed on a user-friendly terminal. The kneepad concept ultimately serves as a case study for extended additive manufactured smart wearables, with potential to be extended towards autonomous feedback and posture correction systems.

Keywords

• Additive manufacturing
• design optimization
• stereolitography
• wearable sensors