Babak Hejrati: Research Activities and Profile Summaries

My research areas include control, design and fabrication, robotic-assisted gait rehabilitation, in which I use robotic technology and human motion analysis to design devices for assisting individuals with lower- and upper- extremities impairments. Such robotic devices can be also used to enhance human performance through power augmentation (e.g., wearable exoskeleton) and training (e.g., virtual reality and simulators).  My research has focused on two major topics: first, creating a realistic walking experience on an advanced robotic locomotion interface called the Treadport to simulate overground walking in a virtual environment; second, design and fabrication of an Underactuated WEarable Arm swing Rehabilitator called UWEAR that aims at integrating arm swing in gait rehabilitation.

The first topic addresses one of the shortcomings in the current gait rehabilitation exercises for patients with walking impairments. These exercises usually fail to depict realistic walking experiences for patients during their training, thus these patients often reach a recovery plateau that makes returning to everyday life difficult. To alleviate this problem, the Treadport locomotion interface has been proposed as a walking simulator that provides more realistic walking experience for patients. A novel controller was implemented for the Treadport belt to regulate the users position to some reference position (typically near the center); when combined with the users volition, this same controller also enables the user to naturally self-select their walking speed as they would when walking over ground. The findings of this study should generalize to any locomotion interface that enables walking with self-selected speed.

The second research topic is concerned with another shortcoming of current rehabilitation exercises, where they de-emphasize the role of upper limbs in inducing lower-limb muscle activity. However, it is found that the inclusion of upper limbs in gait training can result in a faster walking recovery. The designed UWEAR is backdrivable, wearable, capable of assisting the users’ arm swing in the sagittal plane, and has unhindered kinematics in the remaining unactuated degrees of freedom. A data-driven mathematical model was also developed to generate appropriate trajectories with certain characteristics to be used by the UWEAR for inducing arm swing in real-time. The model utilizes the user’s thigh angular velocity and creates arm-swing trajectories during walking with self-select speeds.

Two PhD positions are available for Fall 2018 in the exciting and rapidly growing areas of wearable robotics, virtual reality, and robot-assisted gait rehabilitation for motivated and hard work students. The successful candidates will work on designing and controlling of robotic devices that can be used for helping people with movement problems (i.e., walking impairments and hand neurological dysfunctions).