Towards Embroidered Sensing Technologies for a Lower Limb Soft Exoskeleton

In this work we describe the developments of soft mechanical sensing technologies for XoSoft, a soft lower-limb exoskeleton for assisting people with low to moderate levels or reduced mobility. Starting from the results obtained in integrating capacitive strain sensors in standalone knee and ankle modules, we embed the capacitance constituent electrodes directly in the garment fabric, still guaranteeing an electrically shielded design. Embroidery of conductive yarns with F-head and W-head were tested, varying several parameters, such as stitch length and distance, presser foot height, and geometry (zig-zag patterns). Based on these techniques, a novel sensorized kneepad was fabricated. The adopted solutions make the sensing system more robust, improve both wearability and user comfort, and are expected to allow long term monitoring of joint movements.