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Published in Dag K. Brune, Christer Edling, Occupational Hazards in the Health Professions, 2020
Lever action can be illustrated by a rod or pole hinged around a pivot point, a fulcrum. A force applied causes the lever to rotate. The turning action is determined by the turning moment, or torque, which is equal to the length of the lever arm multiplied by the force component perpendicular to the lever, or equivalently, the force multiplied by the perpendicular distance to the pivot point (Figure 1). Because of the multiplying action of the lever, either a gain in force or in distance can be accomplished. One can say that “what is gained in force is lost in distance” and vice versa. For a given force, a longer lever gives a larger turning moment than a shorter one. The lever is one of the simplest machines known.
A new primary mobility tool for the visually impaired: A white cane—adaptive mobility device hybrid
Published in Assistive Technology, 2018
John-Ross Rizzo, Kyle Conti, Teena Thomas, Todd E. Hudson, Robert Wall Emerson, Dae Shik Kim
The folding wing apparatus was made up of 10 pieces of 30% glass-filled Nylon 66. The elements included: two sleeves that traversed the length of the shaft, and whose relative position defined the open angle of the two wings, a series of four linkages (two per side) that connected the sleeves to the wings, two runners, and two wheels. The runners were casings that held the wheels, which were CNC-machined from Delrin; the runners were configured in a lateral position relative to the width of the wing. The wings were closed by bringing the sleeves closer together and opened by separating them as far as the linkages allowed—this was accomplished by deploying a spring-loaded, lever-action clasp with teeth that was pushed inward to disengage and released to re-engage, allowing the wings to open when pushed inward and combined with a gentle sliding of the sleeves proximally for closing or distally for opening. The wheels pivoted about a hinge in the wing to minimize the amount of space taken up by the folded prototype. Connections between parts of the wing assembly were secured with screws and metal pins.
Wearable artificial skin layer for the reconstruction of touched geometry by morphological computation
Published in Advanced Robotics, 2018
Toshinobu Takei, Mitsuhito Ando, Hiromi Mochiyama
There have been some efforts to develop special tactile sensors for detecting surface undulations. Kikuuwe et al. [3] have developed a handheld tactile sensor utilizing the lever action of TouchLens. However, this sensor is too stiff to be applied to the tracing of a curved surface. Tanaka et al. [1] have also developed a flexible and soft finger-mounted tactile sensor for the detection of surface irregularities. However, the effectiveness of this sensor in detecting tiny undulations has not yet been demonstrated. The irregularity threshold of the sensor output signal must be identified for a specified inspection task because the sensor outputs have not been quantitatively evaluated in comparison with the shapes of surface undulations.
Investigating the normal and tangential peeling behaviour of gecko spatulae using a coupled adhesion-friction model
Published in The Journal of Adhesion, 2021
Saipraneeth Gouravaraju, Roger A. Sauer, Sachin Singh Gautam
It has been observed that during the attachment step, geckos perform a roll in action to grip their toes when they adhere to a substrate and they peel off their toes while detaching (which is called digital hyperextension).[6,11] The gripping action causes the setae to slide very slightly and brings the spatulae in contact with the substrate. At the same time, this gripping action also changes the angle between the setal shaft and the substrate, which in turn decreases the angle between the spatula shaft and the substrate.[17] This dragging at a low angle causes the spatulae to stretch[20,41], increasing the stored strain energy (see Figures 5 and 10). This corresponds to tangentially-constrained peeling: As shown in sections 5.1 to 5.4 (see Figure 7 to 11) the spatulae stretch and very high maximum pull-off forces are reached at small resultant force angles. Similarly, when the gecko hyperextends its toes to disengage from the substrate this again changes the angle between the seta shaft and the substrate. Rolling out the toes results in a lever action of the setal shafts as described by Tian et al.[17] Autumn et al.[46] observed that the seta spontaneously detaches from the substrate when the angle between seta shaft and the substrate increases above . At the spatula level, these actions increase the angle between the spatula shaft and the substrate to and one by one each spatula disengages from the substrate. This spatula disengagement corresponds to tangentially-free peeling: As seen from the results in Figure 19 this action requires very small amount of force.