Drop foot, a loss of use of the muscles that lift the foot, can be caused by stroke, cerebral palsy (CP), multiple sclerosis (MS), or neurological trauma. The two major complications of drop foot are slapping of the foot after heel strike (foot slap) and dragging of the toe during swing (toe drag). The current assistive device is the Ankle Foot Orthosis (AFO), which though offering some biomechanical benefits, is non-adaptive and fails to eliminate significant gait complications. An Active Ankle Foot Orthosis (AAFO) is presented where the impedance of the orthotic joint is modulated throughout the walking cycle to treat drop foot gait. To prevent foot slap, a biomimetic torsional spring control is applied where orthotic joint stiffness is actively adjusted to mi-nimize forefoot collisions with the ground. Throughout late stance, joint impedance is minimized so as not to impede powered plan-tar flexion movements, and during the swing phase, a torsional spring-damper (PD) control lifts the foot to provide toe clearance. To assess the clinical effects of variable-impedance control, kinetic and kinematic gait data were collected on two drop foot parti-cipants wearing the AAFO. For each participant, zero, constant and variable impedance control strategies were evaluated, and the re-sults were compared to the mechanics of three age, weight and height matched normals. It was found that actively adjusting joint im-pedance significantly reduces the occurrence of slap foot, allows greater powered plantar flexion, and provides for greater biolo-gical realism in swing phase ankle dynamics. These results indicate that a variable-impedance orthosis may have certain clinical benefits for the treatment of drop foot gait compared to conventional AFO having zero or constant stiffness joint behaviors.

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The purpose of this technical note is to report the development of a cell-based assay for the detection of endocrine disrupting activity related to crustacean and insect molting and to provide a detailed laboratory protocol for its conduct.

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A magnetorheological knee prosthesis is presented that automatically adapts knee damping to the gait of the amputee using only local sensing of knee force, torque, and position. To assess the clinical effects of the user-adaptive knee prosthesis, kinematic gait da-ta were collected on four unilateral trans-femoral amputees. Using the user-adaptive knee and a conventional, non-adaptive knee, gait kinematics were evaluated on both affected and unaffected sides. Results were compared to the kinematics of 12 age, weight and height matched normals. We find that the useradaptive knee successfully controls early stance damping, enabling amputee to undergo biologically-realistic, early stance knee flexion. These results indicate that a useradaptive control scheme and local mechanical sensing are all that is required for amputees to walk with an increased level of biological realism compared to mechanically passive prosthetic systems.

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Using pre-recorded human motion and trajectory tracking, we can control the motion of a humanoid robot for free-space, upper body gestures. However, the number of degrees of freedom, range of joint motion, and achievable joint velocities of today’s humanoid robots are far more limited than those of the average human subject. In this paper, we explore a set of techniques for limiting human motion of upper body gestures to that achievable by a Sarcos humanoid robot located at ATR. We assess the quality of the results by comparing the motion of the human actor to that of the robot, both visually and quantitatively.

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There are numerous applications of VR simulation re-quiring the grasping and manipulation of virtual objects. Standard-use haptic interfaces (e.g. Virtuose 6D, PHANToM) allow only a limited level of realism, as grasping is approximated through a metaphor (e.g. pressing a button for grasping an object). Existing hand exoskeletons have also certain drawbacks (e.g. feedback only for finger flexion, limited finger workspace etc.). The work presented in this paper introdu-ces a hand force exoskeleton that allows full finger flexion and extension and applies bi-directional feed-back. It has 3dof at the index finger and 4 at the thumb. The system is actuated by DC motors and cable transmissions are used. It has been designed for use in conjunction with Virtuose 6D, a commercial 6dof haptic arm, in order to allow the simulation of external forces (gravity, contact reaction forces, etc.).

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