A direct-drive active compliant end-effector (10) comprises a planar linkage (28) having input links (30, 44) driven by motors (24, 26). A force sensor (52) is connected between the output link (36) and a tool mount (48) for measuring tool interaction forces, signals representative of which together with those representative of angular displacement and velocity of the input links (30, 44) are used by a controller (82) for controlling the drive motors (24, 26) to provide active electronic compliancy.

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We have reviewed our recent results with functional bracing of tibial shaft fractures in adults in order to define its role in management. We also analysed several parameters of these fractures to discover those which influence healing. A total of 780 tibial fractures treated in prefabricated functional braces were followed to union; shortening of less than 10 mm and angulation of less than 5#{1i7n6} any plane were our parameters for successful treatment. The average time before applying a brace was 3.8 weeks for closed fractures and 5.2 weeks for open ones. Closed fractures healed in an average of 17.4 weeks and open fractures in an average of 21.7 weeks, 90% of them with 10 mm of shortening or less. Varus angulation and posterior angulation were the most common defor-mities encountered at union. There were 20 nonunions (2.5%) and 46 braces were discontinued during treatment. We found no associ-ation between fracture healing and the patient’s age, the mechanism of injury or the fracture location. The degree of soft tissue injury appeared to have most influence on the speed of fracture healing. Fracture comminution and initial displacement,the con-dition of the fibula and the time from injury to bracing also appeared to affect the speed of union.

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A robot (10) includes a statically-balanced direct-drive arm (14) having three degrees of freedom, all of which are independent articulated drive joints, the driving axes of two of which intersect at the center of gravity of the arm to eliminate gravity forces on the drive system without counterweights.

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The problem of developing a model to describe and study human gait was undertaken using Lagrangian mechanics. The approach is that of the initial value problem, i.e. starting with the initial conditions which are the limb angles and velocities, and the system inputs which are the applied joint moments, the system response is found. Seven segments are used to model the human body with complete three segment lower limbs, and the head arms and trunk included as one segment. There are six joints, two each at the hips, knees, and ankles. To show the behavior of the developed model a set of initial conditions and moment histories were obtained from measurements in a gait laboratory. Using these data with minor modifications, it is shown that the model progresses through the normal walking cycle, or with minor perturbations, atypical gait patterns can be demonstrated. It is hoped that this model will provide further insight into human gait. For example, alterations of the time histories of the joint moments can be used to predict how certain muscle groups affect gait. Thus the teaching of the comp-lexities of gait will be facilitated. Ultimately, predictions concerning the results of therapy and sur-gery might be made using this model as a diagnostic tool. The emphasis in this paper is on the development of the mathematical model and not on numerical results.

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In the performance of this contract, the state-of-the-art in Bilateral manipulator type man-augmentation systems was dramatically advanced. At the inception of this program, such systems typically handled a maximum of approximately 100 lbs., were large and heavy in relation to their payloads and were generally suited only for remote operation. By contrazt, the Hardiman I prototype, consisting of thirty powere. Joints, can lift itself plus loads equal to its own veight of 1500 lbs. It is packaged to be worn by a man and mimic his motions, maintaining the man’s dexterity and «feel» of the task being performed. In addition to the obvious mechanical design constraints of packaging such a system, it was necessary to achieve substantial technical breakthroughs in the design and analysis of high-load bilateral servosystems. The control technology advances achieved on this program have been instrumental in the development of new concepts in handling ordnance and general cargo for military ap-plications.

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