Closing Force Evaluation of a Sample Return Capsule for a Phobos Sample Return Mission

The mission objective of the Phobos Sample Return is to collect and return 100 g of Phobos’ surface material to Earth inside a tight enclosure composed of a Vault, a Sample Container and sealing elements. One important aspect of the project was the development of a closing mechanism capable of ensuring a pushing force high enough compared to the available force of the robotic arm (40 N). The need for a higher pushing force derived from the design tests which were carried out to experimentally determine the necessary force to overcome the resistance of the sealing element when the vault is closed. Two types of sealing elements, custom made for this project, along with two SC with different geometrical shapes in the sealing area were tested. For better accuracy, the tests considered the imposed operational temperature domain for the vault, ECSS standards and the test rig set-up being performed at environmental temperature (+20 °C), −20 °C, −60 °C and +70 °C. The results of the tests highlighted that the negative temperature has a significant influence over the closing force, as this force is increasing once the operational temperature is decreasing. Based on the work performed, the most suitable type of sealing element was identified, in particular the piston geometry which allows a smaller force to close the vault.

Direct and biometrical estimates of the closing force of major claws of the sand fiddler crab Leptuca pugilator (Bosc, 1801) (Decapoda: Brachyura: Ocypodidae): Support for the weakening combatant hypothesis

Many conclusions concerning the functional biology of crab claws rely upon biometrical estimates of closing force, based upon measures of muscle cross-sectional area and mechanical advantage. Fiddler crab closing force patterns show variation with body size, claw size, location of the opposing claw tips, and physiological condition, so we have measured closing force of the sand fiddler crab Leptuca pugilator (Bosc, 1801) as a function of claw size, force exerted at claw tips, and at the commonly well-developed pollex tooth. Leptuca pugilator has an elongated claw with gracile dactyl and pollex. As predicted by biometrical proportions, closing force is greater at the pollex tooth than at the claw tip. The pollex tooth does shift with increasing claw size in relative position toward the claw hinge. Mechanical advantage at the pollex tooth and dactyl tip both decline with increasing claw length. But there is no difference in slope of log closing force as a function of log claw length between the pollex position and terminus of the dactyl, which demonstrates that force exerted at the pollex tooth has no impact on proportional change in closing force with increasing claw size. The log-log slope is ~0.9, reflecting the proportionally decreasing muscle cross-sectional area and lowering mechanical advantage with increasing claw size. For both the pollex tooth and the claw tip, mechanical advantage decreases very slightly with increasing claw size, but closing force proportionally decreases with increasing claw size, supporting the weakening combatant hypothesis for this species.

A soft, synergy-based robotic glove for grasping assistance

This paper presents a soft, tendon-driven, robotic glove designed to augment grasp capability and provide rehabilitation assistance for postspinal cord injury patients. The basis of the design is an underactuation approach utilizing postural synergies of the hand to support a large variety of grasps with a single actuator. The glove is lightweight, easy to don, and generates sufficient hand closing force to assist with activities of daily living. Device efficiency was examined through a characterization of the power transmission elements, and output force production was observed to be linear in both cylindrical and pinch grasp configurations. We further show that, as a result of the synergy-inspired actuation strategy, the glove only slightly alters the distribution of forces across the fingers, compared to a natural, unassisted grasping pattern. Finally, a preliminary case study was conducted using a participant suffering from an incomplete spinal cord injury (C7). It was found that through the use of the glove, the participant was able to achieve a 50% performance improvement (from four to six blocks) in a standard Box and Block test.

Quantitative evaluation of elasticity of lower orbicularis oris muscle during the lip closing measurement using sonographic elastography

BACKGROUND: Lip closing functions have never been evaluated from the viewpoint of elastic properties. OBJECTIVES: The purpose of the present study was to investigate the behavior of the lower orbicularis oris muscle during a button-pull exercise to measure lip closing force and quantitatively evaluate its elastic properties using sonographic elastography. METHODS: Appropriate compression loads for elastography were randomly measured on one of three types of acoustic couplers on three examiners. Compression tests were performed on three types of acoustic couplers within the appropriate compression load. Using the acoustic coupler with the lowest elastic modulus, the strain ratio of the lower orbicularis oris muscle during lip closing was measured, and elastography was performed on six males under tension loads of 0–8 N. RESULTS: The intraclass correlation coefficient (1, 3) for the tension load of 0 N was 0.81. Elastography showed that the strain ratio values increased significantly (p < 0.05) as the tension load increased. CONCLUSIONS: Combining the data obtained from lip closing test devices and sonographic elastography enabled the muscle performance to be evaluated objectively and accurately.

Modeling and robotic handling of a snap-fitting box buckle

Modeling and robotic handling of a plastic box buckle is discussed in this paper. The closing mechanism of the box buckle is simulated to determine the characteristic of the nonlinear load-deflection curve. An intelligent end-effector was designed and manufactured to handle the assembly with a robot. The closing force is measured by a built-in load cell and its values are processed by a micro-controller. The intelligent end-effector can be used in a robotic system, which deals with different snap-fit applications.

Tribute to Milton D. Heifetz (1921-2015): The Man Behind the Heifetz Aneurysm Clip

Milton Dave Heifetz (1921-2013) was a pioneer American neurosurgeon who spent the majority of his career at Cedars-Sinai Hospital in California. Heifetz greatly influenced the field of neurosurgery as an innovator, leader, and academic neurosurgeon. His redesign of the aneurysm clip addressed the long-standing issue of a fatiguing spring. Heifetz's innovation allowed the spring to maintain adequate closing force despite repetitive opening and closing. This clip was recognized as one of the most effective aneurysm clips for approximately 15 yr. While he was best known for this eponymous aneurysm clip, Heifetz also developed other various microsurgical instruments and tools for stereotactic approaches. Beyond neurosurgery, he was an influential figure and well-published author in fields such as medical ethics, philosophy, astronomy, and poetry. In 1975, he published The Right to Die: A Neurosurgeon Speaks of Death With Candor, a book which played a major role in our modern-day advanced directives. Throughout his life, Heifetz was an inspirational individual who consistently worked towards solutions to surgical and ethical problems. We present a historical vignette on his life, career, and contributions to neurosurgery.

THE EFFECT OF ADJUSTMENT OF ADAPTIVE FRICTION CLUTCHES OF THE SECOND GENERATION THE SHAPE OF THE LOAD CHARACTERISTIC CURVE AND THE ACCURACY OF THE RESPONSE

The technical characteristics of the adaptive coupling with separate closure (the first option) as a result of its adjustment are determined. It is shown that when the closing force and load decrease, the accuracy of the device response increases, and vice versa.