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Body Systems: The Basics
Published in Karen L. LaBat, Karen S. Ryan, Human Body, 2019
The pivot joint allows rotation of one bone relative to another. A projection of one bone fits into a ring-like ligament of a second bone, allowing the first bone to rotate perpendicularly (see Figure 2.6). You can pivot your head from left to right because the first two vertebrae at the top of the spinal column allow a significant pivotal motion, although you cannot rotate your head 360 degrees. You can rotate your hand into a palm up/palm down position because of the pivot joint at the elbow between the two bones of the forearm, the radius and the ulna, stabilized by the interosseous membrane between them.
Kinematic Design
Published in Richard Leach, Stuart T. Smith, Basics of Precision Engineering, 2017
The pivot joint allows only a rotation around one axis between two parts of a mechanism. A pivot joint can be built with a cylindrical contact, as shown in Figure 6.17, and a point contact, as shown in Figure 6.11, with a surface normal parallel to the central axis of the cylindrical contact. The pivot joint has one degree of freedom.
Anatomy, Biomechanics, Work Physiology, and Anthropometry
Published in Stephan Konz, Steven Johnson, Work Design, 2018
Pivot joints (e.g., elbow) allow rotation. The elbow has a pivot joint of the smaller bone in your forearm (the radius, on the thumb side) and the larger forearm bone (the ulna); it allows you to place your palm up or down.
Proximity-based non-contact perception and omnidirectional point-cloud generation based on hierarchical information on fingertip proximity sensors
Published in Advanced Robotics, 2021
The experimental results for finger #2 are shown in Figure 10. In addition to the rotation of the flexion joints such as finger #1, the rotation of the pivot joint was generated so that the fingertip was oriented toward the center with respect to the sphere. For the cube, the fingertip slightly touched the vertex and continued to trace near the edge without pivoting. This is because the initial position of the fingertip occured under the condition that the sensitivity of the lower-level proximity data was low, which is a disadvantage to the reactive controller. This shows that the reactive control of distance makes the fingertip too close to the object because the intensity of reflected light is weak at vertices and edges. The reactive control of pivoting is also weak because the light reflected from both sides of the edge is balanced. It is expected that this problem can be solved by combining the perception motion with the twist motion of the wrist.
Glasses-type wearable computer displays: usability considerations examined with a 3D glasses case study
Published in Ergonomics, 2018
Joonho Chang, Seung Ki Moon, Kihyo Jung, Wonmo Kim, Matthew Parkinson, Andris Freivalds, Timothy W. Simpson, Seon Pill Baik
Considering the results of the case study and practicality, the following design advice can be addressed to improve human factors issues of glasses-type wearable computer displays. First, for better weight balance of a glasses-type wearable computer display, objects such as batteries and circuits on the temples of glasses should be placed near the neck pivot joint (called the tragion notch; i.e. around the C1 cervical vertebrae). This is supported by the results of the case study that showed Prototype with weights that were close to the ears (7 cm away from the lenses along temples) had lower discomfort ratings than glasses A and B with weights on the front (1.5 cm back from the lenses) of the temples. In addition, this is consistent with the traditional design requirement of helmets (including head-mounted display systems) emphasising that the centre of mass of helmets should be placed near the tragion notch (Ashrafiuon, Alem, and McEntire 1997; McEntire and Shanahan 1998; Melzer et al. 2009).
Multibody system design based on reference dynamic characteristics: gyroscopic system paradigm
Published in Mechanics Based Design of Structures and Machines, 2023
Ayman A. Nada, Abdullatif H. Bishiri
In this section, the rotary-pendulum shown in Fig. 3 is used to examine the search method illustrated in last section. The rotary-pendulum system consists of an actuated rotary arm controlled by an input torque, whose angular velocity is measured by an encoder, and an un-actuated pendulum connected to the arm at a pivot joint. The pendulum is attached to a hinge instrumented with another encoder at the end of the pendulum arm. This second encoder measures the angular velocity of the pendulum. The system is interfaced by means of a data acquisition card and driven by LabVIEW based real time software.