We are developing exoskeleton robots to realize human shoulder motion assistance for the physically weak. In this paper, we propose controller adjustment for the controller of the exoskeleton robot for human shoulder motion assistance. Motion assistance in the entire movable range of the exoskeleton is realized with a few teaching motion patterns using the proposed controller adjustment. Muscle activity (electromyography) during shoulder motion and motion error between desired user shoulder motion and the measured assisted shoulder motion are evaluated.

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An active ankle-foot orthoses (AAFO) is presented where the impedance of the orthotic joint is modulated throughout the walking cycle to treat drop-foot gait. During controlled plantar flexion, a biomimetic torsional spring control is applied where orthotic joint stiffness is actively adjusted to minimize forefoot collisions with the ground. Throughout late stance, joint impedance is minimized so as not to impede powered plantar flexion movements, and during the swing phase, a torsional spring-damper 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 participants wearing the AAFO. For each participant, zero, constant, and variable impedance control strategies were evaluated and the results were compared to the mechanics of three age, weight, and height matched normals.We find that actively adjusting joint impedance reduces the occurrence of slap foot allows greater powered plantar flexion and provides for less kinematic difference during swing when compared to normals. These results indicate that a variable-impedance orthosis may have certain clinical benefits for the treatment of drop-foot gait compared to conventional ankle-foot orthoses having zero or constant stiff-ness joint behaviors.

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The purpose of this study is to build a control system for a wearable power assisting device, which helps people with lifting heavy things, like a person who can’t move alone in daily life. When we lift something heavy, we use both hands. That’s why a con-trol system that can automatically switch on/off without using hands is necessary. In this study, we analyze human lifting up motion, and reveal characteristics of the motion, to find the suitable timing for switching the wearable power assisting device. Results show that the automatic switching can be realized.

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The first phase of this project began in Fall 2003 with a team of 5 senior students designing and constructing a hydraulically actuated pick and place machine that can pick up 100 lb objects by hydraulically amplifying the human force. Although the prescribed use of the machine is for landscaping use, the machine is actually intended to be the upper extremity portion of the exoskeleton system.

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The Defense Advanced Research Projects Agency (DARPA) inaugurated a program addressing research and development for an Exoskeleton for Human Performance Augmen-tation in FY 2001. A team consisting of Oak Ridge National Laboratory, the prime contractor, AeroViron-ment, Inc., the Army Research Laboratory, the University of Minnesota, and the Virginia Polytechnic Insti-tute has recently completed an 18-month Phase I effort in support of this DARPA program. The Phase I effort focused on the development and proof-of-concept demonstrations for key enabling technologies, lay-ing the foundation for subsequently building and demonstrating a prototype exoskeleton. The overall ap-proach was driven by the need to optimize energy efficiency while providing a system that augmented the operator in as transparent manner as possible (non-impeding). These needs led to the evolution of two key distinguishing features of this team’s approach. The first is the “no knee contact” concept. This concept is dependent on a unique Cartesian-based control scheme that uses force sensing at the foot and backpack attachments to allow the exoskeleton to closely follow the operator while avoiding the difficulty of connecting and sensing position at the knee. The second is an emphasis on energy efficiency manifested by an energetic, power, actuation and controls approach designed to enhance energy efficiency as well as a reconfigurable kinematic structure that provides a non-anthropomorphic configuration to support an energy saving long-range march/transport mode. The enabling technologies addressed in the first phase were controls and sensing, the soft tissue interface between the machine and the operator, the power system, and actuation. The controller approach was implemented and demonstrated on a test stand with an actual operator. Control stability, low operator fatigue, force amplification and the human interface were all successfully demonstrated, validating the controls approach. A unique, lightweight, low profile, multi-axis foot sensor (an integral element of the controls approach) was designed, fabricated, and its perfor-mance verified. A preliminary conceptual design of the human coupling and soft tissue interface, based on biomechanics research has been developed along with a test plan to support an iterative design process. The power system concept, a fuel cell hybrid power supply using chemical generated hydrogen, was succes-sfully demonstrated and shown to be able to efficiently meet both steady-state and transient peak loads. Two actuator approaches, a piezoelectric actuator, with theoretical high power densities and an approach based on a high-performance, high-speed electric motor driving a miniature hydraulic pump have been investigated. The first shows great potential but will require further research before reaching that promise. The other approach has been modeled and simulated and shown to provide the possibility for significant energy savings (>30%) and improved power densities in comparison to conventional hydraulics. Biomechanics analysis and testing were also performed in support of these enabling technologies, to pro-vide a basis for design criteria. An analysis was performed to determine baseline data for initial mecha-nical design and power supply sizing. Testing conducted to evaluate boot sole thickness found that thick-ness increases up to two inches could be accommodated without significant impact on human factors issues. This 18-month long Phase I effort has evaluated key enabling technologies and demonstrated advances in these technologies that have significantly increased the likelihood of building a functional prototype exoskeleton.

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