Harshal Arun Sonar
As the field of robotics continues to grow outside the manufacturing environment into our daily lives, the interactions between humans and robots are increasingly becoming close and dynamic. This type of environment requires robots to be less rigid, multi-functional, safer, and compliant with human bodies. Such robotics interfaces are ideally suited for medical rehabilitation, elderly assistance to at-home entertainment devices. However, the traditional rigid robotic devices fail to address some of the design criteria posed for safety, compliance, and physical limitations on the mechanical design. In the case of wearable technologies, the robotic device additionally requires a lightweight, compliant, and safe interface to provide smooth communication and interaction with humans. The traditional robotic systems are fast, accurate, and can handle large torques. However, they are also, application-specific and not suitable as it is for the wearable scenario due to the contradictory design requirements. In the past decade, soft robotics has emerged as a novel approach to solve the complex problems faced by rigid robots using inherent softness and compliant material properties. The design for the future interactive wearable interfaces thus may lie in the intersection of developments in the fields of wearable technology and soft robotics.Designing a wearable interactive interface with soft materials for wearability, portability, cost-effectiveness, and modularity would be one of the ideal solutions to tackle the wearability challenge. It can be a cost-effective solution for at-home assistive rehabilitation or entertainment. It also allows developing novel methods of soft sensing, actuation, control strategies, and human in loop protocols to maximize the utility of inherent material properties and environment around the robotic device.In my Ph.D. research, I develop and create hardware and software towards an immersive interactive soft virtual-tactile environment focusing on the wearability, portability, easy customization, and modularity aspects. I developed a low profile soft pneumatic actuator-skin (SPA-skin) with distributed sensing and actuation capabilities for testing various levels of complex vibrotactile feedback: the multilayer composite of high-sensitivity PZT pressure sensors and vibratory SPA can produce up to 3 N output force at 0-100 Hz. This demonstrated that SPA-skin produces distinctive and dynamic haptic force feedback under modulated varying time, force, and spatial resolution. Furthermore, a complete framework for designing a tactile feedback skin for specific wearable applications is developed, starting from the material selection and actuator design, and concluding with the validation of the subjectâs perceived feedback. As soon as, the SPA-skin is required to be worn by humans, the complexity of the problem multiplies due to lack of proper grounding to ensure the blocked forces. The platform is further optimized for application space in fMRI compliant environment and a user study protocol for somatosensory thresholds is designed. The modulable and controllable nature of SPA-skinâs tactile feedback provides much-needed validation using BOLD signals from brain imaging. SPA-skin and findings presented herein, provide a foundational platform to further investigate the sensitivity of human skin and decipher mechanoreceptor reactions for a diverse range of human-robot interactions and wearable technology.
EPFL2021
