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Human Machine Interaction (HMI) Laboratory focuses on the design, control, implementation, and evaluation of mechatronic systems that are capable of haptic interaction — physical interaction with the user through the sense of touch. In particular, we develop and analyze principles and tools to enable physical human-robot interaction (pHRI) with a systems and controls perspective. We aim to achieve optimal performance for such systems, while simultaneously ensuring safety and ergonomic nature of interaction under the coupled dynamics of the human-robot system and the constraints imposed by human biomechanics/sensorimotor control. Our research extends to synthesizing algorithms for simulated physical interaction with virtual environments (haptic rendering) and exploring the control theoretical framework of human sensorimotor system through empirical investigations of skill acquisition.

Applications of our research include robotic devices for physical rehabilitation, active exoskeletons and prostheses for human augmentation, force-feedback devices for robot-assisted surgery, haptic interfaces for manual skill training, teleoperators for exploration of hazardous or remote environments, x-by-wire systems for automotive/aerospace industry, and service robots for collaborative task execution with humans. Our research contributes to the fields of robotics, system and controls, multi-body dynamics, mechanical design, biomechanics, physical medicine, and basic science.

Force-Feedback Exoskeletons and Rehabilitation Robotics

Neurological injuries are the leading cause of serious, long-term disability in developed countries. Physical rehabilitation therapy is indispensable for treating neurological disabilities. Therapies are more effective when they are task specific, intense, repetitive, and allow for active involvement of patients. Robotic devices in repetitive and physically involved rehabilitation eliminate the physical burden of movement therapy for the therapists, enable safe and versatile training with increased intensity, allow quantitative measurements of patient progress, increase the reliability, accuracy, and effectiveness of traditional physical rehabilitation therapies, and realize innovative treatment protocols. We have expertise on the design, human-in-the-loop control, implementation, and evaluation of a range of novel powered exoskeletons for robot-assisted rehabilitation targeting the movements of the shoulder, elbow, wrist, hand, finger, pelvis, hip, knee, ankle, and foot. The self-aligning exoskeletons automatically adjust their joint axes to ensure an ideal match between human joint axes and the device axes, not only guaranteeing ergonomy and comfort throughout the therapy, but also extending the usable range of motion for the targeted joints. Moreover, their adjustability feature significantly shortens the setup time required to attach patients to the exoskeletons. These exoskeletons are equipped with safe adaptive controllers that emphasize coordination and synchronization between various degrees of freedom, while leaving exact timing on the desired path to the patient. The controllers provide assistance “as-needed” to enable patient to complete the task, while maximally engaging the patient. Furthermore, the controllers enable delivery of “repetitive tasks without repeating the same task”, while guaranteeing coupled stability of the human-robot system.

Medical Robotics

Laparoscopy, a commonly used minimally invasive surgical procedure, utilizes slender surgical tools and cameras inserted into the abdomen of a patient through small ports on the skin, enabling the surgeon to perform numerous procedures without large incisions. In comparison with traditional open surgical procedures, laparoscopy offers reductions in trauma, post-operative pain, recovery time, and scarring and blood loss for the patient and is more cost effective due to the reduced risk of complications, shorter hospital stays and less medication requirements. Despite the numerous advantages laparoscopy presents for patients, it is quite difficult to master for surgeons. During laparoscopy, the surgeon’s hand motions are reflected about the incision point, known as the fulcrum effect, access to the patient’s body is restricted, and only 2D visual feedback is available resulting in a loss of vital depth perception. Due to the difficulty in mastering laparoscopy, surgical training is indispensable and effective training approaches are crucial.

Virtual reality (VR) simulation, where a trainee virtually interacts with human tissue, is a viable alternative to the conventional laparoscopic surgical training, bridging the gap between the learning process and actually carrying out the real time surgery. VR simulation not only reduces the training costs and number of animal/cadaver experiments, but also makes it possible for the surgical tasks to be repeated as much as required. The incorporation of force feedback into VR simulation enhances the surgeon’s perception of pulling and grasping maneuvers, such that surgeons can grasp tissues with less force and without causing scars. Consequently, this improves the trainee’s overall performance. We specialize on the design, control, implementation, and evaluation of force-feedback laparoscopic training devices and bi-manual haptic interfaces for bilateral teleoperation of such surgical robotic devices.

Robotic Prostheses

Versatile grasping and manipulation in unstructured environments are challenging tasks. Anthropomorphism (ability to emulate human-like hand shape, size, and consistency) and dexterity (successful manipulation capability even under unstructured conditions) are commonly identified as the key features to reach a satisfactory level of performance. Successful manipulation necessitates another significant and commonly neglected characteristics of human hand, namely the impedance modulation. Incorporating impedance modulation property in the design of a hand prosthesis makes it adaptable to interacted objects/tasks. Successful execution of many activities of daily living, where human physically interacts with the environment, arises from proper modulation of the impedance level of hand based on the varying requirements of the task.

We have experience on the design, natural user interface, control, implementation, and evaluation of a low-cost, customizable, easy-to-use hand prosthesis capable of adapting its stiffness. Control of the variable stiffness hand prosthesis is achieved by a surface electromyography based natural human-machine interface, called tele-impedance control. This interface, together with variable stiffness actuation, enables an amputee to modulate the impedance of the prosthetic limb to properly match the requirements of a task, while performing activities of daily living.