**Preliminary Results in Testing of a Novel Asymmetric Underactuated Robotic Hand Exoskeleton for Motor Impairment Rehabilitation**

**Flaviu Ionut, Birouas, 1,**† **, Radu Cătălin T, arcă 1,\* ,**† **, Simona Dzitac 2,**† **and Ioan Dzitac 3,4,\* ,**†


Received: 6 August 2020; Accepted: 3 September 2020; Published: 7 September 2020

**Abstract:** Robotic exoskeletons are a trending topic in both robotics and rehabilitation therapy. The research presented in this paper is a summary of robotic exoskeleton development and testing for a human hand, having application in motor rehabilitation treatment. The mechanical design of the robotic hand exoskeleton implements a novel asymmetric underactuated system and takes into consideration a number of advantages and disadvantages that arose in the literature in previous mechanical design, regarding hand exoskeleton design and also aspects related to the symmetric and asymmetric geometry and behavior of the biological hand. The technology used for the manufacturing and prototyping of the mechanical design is 3D printing. A comprehensive study of the exoskeleton has been done with and without the wearer's hand in the exoskeleton, where multiple feedback sources are used to determine symmetric and asymmetric behaviors related to torque, position, trajectory, and laws of motion. Observations collected during the experimental testing proved to be valuable information in the field of augmenting the human body with robotic devices.

**Keywords:** asymmetric underactuated; rehabilitation; robotic exoskeleton; symmetric and asymmetric trajectory; Bowden cable; video processing data
