Research Projects
Artificial Gastrocnemius
Hugh Herr and Ken EndoBiomimetic Active Prosthesis for Above-Knee Amputees
Hugh Herr, Elliott Rouse and Luke MooneyControl of Muscle-Actuated Systems via Electrical Stimulation
Waleed Farahat and Hugh HerrDancing Control System for Bionic Ankle Prosthesis
Hugh Herr, Bevin Lin, Elliott Rouse, Nathan Villagaray-Carski and Robert EmersonProfessional ballroom dancer Adrianne Haslet-Davis lost her natural ability to dance when her left leg was amputated below the knee following the Boston Marathon bombings in April 2013. Hugh Herr was introduced to Adrianne while meeting with bombing survivors at Boston's Spaulding Rehabilitation Hospital. For Professor Herr, this meeting generated a research challenge: build Adrianne a bionic ankle prosthesis, and restore her ability to dance. The research team for this project spent some 200 days studying the biomechanics of dancing and designing the bionic technology based on their investigations. The control system for Adrianne was implemented on a customized BiOM bionic ankle prosthesis.
Effect of a Powered Ankle on Shock Absorption and Interfacial Pressure
Hugh Herr and David HillLower-extremity amputees face a series of potentially serious post-operative complications. Among these are increased risk of further amputations, excessive stress on the unaffected and residual limbs, and discomfort at the human-prosthesis interface. Currently, conventional, passive prostheses have made strides towards alleviating the risk of experiencing complications, but we believe that the limit of "dumb" elastic prostheses has been reached; in order to make further strides we must integrate "smart" technology in the form of sensors and actuators into lower-limb prostheses. This project compares the elements of shock absorption and socket pressure between passive and active ankle-foot prostheses. It is an attempt to quantitatively evaluate the patient's comfort.
FitSocket: Measurement for Attaching Objects to People
Arthur Petron, Hugh Herr and Neri OxmanA better understanding of the biomechanics of human tissue allows for better attachment of load-bearing objects to people. Think of shoes, ski boots, car seats, orthotics, and more. We are focusing on prosthetic sockets, the cup-shaped devices that attach an amputated limb to a lower-limb prosthesis, which currently are made through unscientific, artisanal methods that do not have repeatable quality and comfort from one individual to the next. The FitSocket project aims to identify the correlation between leg tissue properties and the design of a comfortable socket. The FitSocket is a robotic socket measurement device that directly measures tissue properties. With these data, we can rapid-prototype test sockets and socket molds in order to make rigid, spatially variable stiffness, and spatially/temporally variable stiffness sockets.
FlexSEA: Flexible, Scalable Electronics Architecture for Wearable Robotics Applications
Hugh Herr and Jean-Francois DuvalThis project aims to enable fast prototyping of a multi-axis and multi-joint active prosthesis by developing a new modular electronics system. This system provides the required hardware and software to do precise motion control, data acquisition, and networking. Scalability is achieved through the use of a fast industrial communication protocol between the modules, and by a standardization of the peripherals' interfaces: it is possible to add functionalities to the system simply by plugging in additional cards. Hardware and software encapsulation are used to provide high-performance, real-time control of the actuators, while keeping the high-level algorithmic development and prototyping simple, fast, and easy.
Human Walking Model Predicts Joint Mechanics, Electromyography, and Mechanical Economy
Hugh Herr, Matthew Furtney and Stanford Research InstituteLoad-Bearing Exoskeleton for Augmentation of Human Running
Hugh Herr, Grant Elliott and Andrew MareckiNeural Interface Technology for Advanced Prosthetic Limbs
Edward Boyden, Hugh Herr, Ron Riso and Katherine SongRecent advances in artificial limbs have resulted in the provision of powered ankle and knee function for lower extremity amputees and powered elbow, wrist, and finger joints for upper extremity prostheses. Researchers still struggle, however, with how to provide prosthesis users with full volitional and simultaneous control of the powered joints. This project seeks to develop means to allow amputees to control their powered prostheses by activating the peripheral nerves present in their residual limb. Such neural control can be more natural than currently used myoelectric control, since the same functions previously served by particular motor fascicles can be directed to the corresponding prosthesis actuators for simultaneous joint control, as in normal limbs. Future plans include the capability to electrically activate the sensory components of residual limb nerves to provide amputees with tactile feedback and an awareness of joint position from their prostheses.
Powered Ankle-Foot Prosthesis
Hugh HerrSensor-Fusions for an EMG Controlled Robotic Prosthesis
Matthew Todd Farrell and Hugh HerrCurrent unmotorized prostheses do not provide adequate energy return during late stance to improve level-ground locomotion. Robotic prostheses can provide power during late-stance to improve metabolic economy in an amputee during level-ground walking. This project seeks to improve the types of terrain a robotic ankle can successfully navigate by using command signals taken from the intact and residual limbs of an amputee. By combining these command signals with sensors attached to the robotic ankle, it might be possible to further understand the role of physiological signals in the terrain adaptation of robotic ankles.
Terrain-Adaptive Lower Limb Prosthesis
Hugh Herr and Roman StolyarovAlthough there have been great advances in the control of lower extremity prostheses, transitioning between terrains such as ramps or stairs remains a major challenge for the field. The mobility of leg amputees is thus limited, impacting their quality of life and independence. This projects aims to solve this problem by designing, implementing, and integrating a combined terrain-adaptive and volitional controller for powered lower limb prostheses. The controller will be able to predict terrain changes using data from both intrinsic sensors and electromyography (EMG) signals from the user; adapt the ankle position before footfall in a biologically accurate manner; and provide a torque profile consistent with biological ankle kinetics during stance. The result will allow amputees to traverse and transition among flat ground, stairs, and slopes of varying grade with lower energy and pain, greater balance, and without manually changing the walking mode of their prosthesis.
Tethered Robotic System for Understanding Human Movements
Hugh Herr and Jiun-Yih KuanThe goal of this project is to build a powerful system as a scientific tool for bridging the gap in the literature by determining the dynamic biomechanics of the lower-limb joints and metabolic effects of physical interventions during natural locomotion. This system is meant for use in applying forces to the human body and measuring the force, displacement, and other physiological properties simultaneously, helping investigate controllability and efficacy of mechanical devices physically interacting with a human subject.
Variable-Impedance Prosthetic (VIPr) Socket Design
Hugh Herr, Arthur J Petron, Bryan Ranger and David SengehToday, 100 percent of amputees experience some form of prosthetic socket discomfort. This project involves the design and production of a comfortable, variable impedance prosthetic (VIPr) socket using digital anatomical data for a transtibial amputee using computer-aided design and manufacturing (CAD/CAM). The VIPr socket uses multiple materials to achieve compliance, thereby increasing socket comfort for amputees, while maintaining structural integrity. The compliant features are seamlessly integrated into the 3D-printed socket to achieve lower interface peak pressures over bony protuberances and other anatomical points in comparison to a conventional socket. This lower peak pressure is achieved through a design that uses anthropomorphic data acquired through surface scan and Magnetic Resonance Imaging techniques. A mathematical transformation maps the quantitative measurements of the human residual limb to the corresponding socket shape and impedance characteristics, spatially.
Volitional Control of a Powered Ankle-Foot Prosthesis
Hugh Herr and Oliver KannapeThis project focuses on giving transtibial amputees volitional control over their prostheses by combining electromyographic (EMG) activity from the amputees' residual limb muscles with intrinsic controllers on the prosthesis. The aim is to generalize biomimetic behavior of the prosthesis, making it independent of walking terrains and transitions.