Fabrication, nonlinear modeling, and control of woven hydraulic artificial muscles for wearable applications

Soft robotics, soft artificial muscles and smart textiles are on the rise to compete with their rigid counterparts in the fields of wearable technologies and medical applications owing largely to their improved compliance characteristics. This paper introduces a smart textile created by weaving a hydraulic artificial muscle for a wearable application. To capture the inherent nonlinear hysteresis of the developed smart woven textile, we propose a simple hysteresis model and implement a feedforward compensation scheme and an adaptive controller. Both control strategies significantly reduced the output elongation tracking errors, demonstrating up to 90% improvement in the case of adaptive control compared to the uncompensated system. We also present the development of a portable smart compression device to overcome the shortcomings of current compression devices to provide treatment for people with venous disease or compromised peripheral blood flow. While current compression devices are passive, difficult to put on/take off, slow to compress or noisy and bulky, our smart compression device is easy to wear, compact and portable, with low energy consumption and can be easily controlled with a smartphone application via Bluetooth connection. The smart compression device operated at 18% strain and took 5 s to complete each compression cycle. We also demonstrate the proof-of-concept of incorporating a soft contact force sensor and other electronic components into the smart textile structure for extra functionality. This work contributes to the advancement of soft robotic technologies, wearable electronics and smart wearables for medical applications.