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Extraterrestrial Drilling and Excavation
Published in Yoseph Bar-Cohen, Kris Zacny, Advances in Extraterrestrial Drilling, 2020
Kris Zacny, Gale Paulsen, Phil Chu, Boleslaw Mellerowicz, Stephen Indyk, Justin Spring, Alex Wang, Grayson Adams, Leslie Alarid, Colin Andrew, Jameil Bailey, Ron Bergman, Dean Bergman, Jocelyn Bergman, Phil Beard, Andrew Bocklund, Natasha Bouey, Ben Bradley, Michael Buchbinder, Kathryn Bywaters, Lee Carlson, Conner Castle, Mark Chapman, Colin Chen, Paul Chow, Evan Cloninger, Patrick Corrigan, Tighe Costa, Paul Creekmore, Kiel Davis, Stella Dearing, Jack Emery, Zak Fitzgerald, Steve Ford, Sam Goldman, Barry Goldstein, Stephen Gorevan, Amelia Grossman, Ashley Hames, Nathan Heidt, Ron Hayes, Matt Heltsley, Jason Herman, Joe Hernandez, Greg Hix, Will Hovik, Robert Huddleston, Kevin Humphrey, Anchal Jain, Nathan Jensen, Marnie Johnson, Helen Jung, Robert Kancans, Cecily Keim, Sarineh Keshish, Michael Killian, Caitlin King, Isabel King, Daniel Kim, Emily Kolenbrander, Sherman Lam, Andrea Lamore, Caleb Lang, Joseph Lee, Carolyn Lee, John Lorbiecki, Kathryn Luczek, Jacob Madden, Jessica Maddin, Tibor Makai, Mike Maksymuk, Zach Mank, Richard Margulieux, Sara Martinez, Yuka Matsuyama, Andrew Maurer, Molly McCormick, Jerry Moreland, Phil Morrison, Erik Mumm, Adoni Netter, Jeff Neumeister, Tim Newbold, Joey Niehay, Phil Ng, Peter Ngo, Huey Nguyen, Tom O’Bannon, Sean O’Brien, Joey Palmowski, Aayush Parekh, Andrew Peekema, Fredrik Rehnmark, Hunter Rideout, Albert Ridilla, Alexandra Rzepiejewska, Dara Sabahi, Yoni Saltzman, Luke Sanasarian, Vishnu Sanigepalli, Emily Seto, Jeff Shasho, Sase Singh, David Smyth, Nancy Sohm, Jesus Sosa, Joey Sparta, Leo Stolov, Marta Stone, Andrew Tallaksen, Miranda Tanouye, Lisa Thomas, Thomas Thomas, Luke Thompson, Mary Tirrell, Nick Traeden, Ethan Tram, Sarah Tye, Crystal Ulloa, Dylan Van-Dyne, Robert Van Ness, Vincent Vendiola, Brian Vogel, Lillian Ware, Bobby Wei, Hunter Williams, Jack Wilson, Brian Yaggi, Bernice Yen, Sean Yoon, Ben Younes, David Yu, Michael Yu, Mike Zasadzien, Raymond Zheng, Yoseph Bar-Cohen, Mircea Badescu, Xiaoqi Bao, Tom Cwik, Jean-Pierre Fleurial, Jeffery Hall, Kevin Hand, Ben Hockman, Samuel M. Howell, Troy Lee Hudson, Shannon Jackson, Hyeong Jae Lee, Michael Malaska, Brandon Metz, Scott Moreland, Avi Okon, Tyler Okamoto, Dario Riccobono, Kris Sherrill, Stewart Sherrit, Miles Smith, Jurgen Mueller, Wayne Zimmerman, Michael Amato, Melissa Trainer, Don Wegel, Andrej Grubisic, Walter F. Smith, Ralph Lorenz, Elizabeth Turtle, Hirotaka Sawada, Hiroki Kato, Yasutaka Satou, Takashi Kubota, Masaki Fujimoto, Pietro Baglioni, Stephen Durrant, Richard Fisackerly, Roland Trautner, Marek Banaszkiewicz, Karol Seweryn, Akihiro Fujiwara, Taro Nakamura, Matthias Grott, Jerzy Grygorczuk, Bartosz Kędziora, Łukasz Wiśniewski, Tomasz Kuciński, Gordon Wasilewski, Seiichi Nagihara, Rohit Bhartia, Hiroyuki Kawamoto, Julius Rix, Robert Mulvaney, Andrea Rusconi, Christian Panza, Marco Peruzzotti, Pablo Sobron, Ryan Timoney, Kevin Worrall, Patrick Harkness, Naohiro Uyama, Hiroshi Kanamori, Shigeru Aoki, Dale Winebrenner, Yasuyuki Yamada, Tilman Spohn, Christian Krause, Torben Wippermann, Roy Lichtenheldt
The primary components of the sampler are shown in Figure 1.23. To prepare the BiBlade for sampling, the actuator rotates the roller screw to drive the gripper (roller screw nut is part of the gripper) into contact with the shuttle. The fingers of the gripper passively lock onto the shuttle at the shuttle latching plate. The actuator then pulls the gripper back which pulls the shuttle back while compressing the sampling springs. The shuttle pulls the carriages and blades up the carriage rails using the pushrods. The gripper stops and is held in a retracted position just before the firing location. The gripper is then pulled back a few mm further which causes the back of the fingers to contact the rigid release plate and release the shuttle, which is then pushed down the shuttle rails by the sampling springs. The shuttle motion causes the blades to move down the carriage rails and penetrate the comet surface at a speed of approximately 10 m/s. The blade motion is stopped by hard stops and overload springs to absorb the residual energy that was not used by the blades to acquire the sample. The overload springs also prevent damage to the blades if impacting perfectly rigid surfaces.
Lubrication and Wear Analysis of Planetary Roller Screw Mechanism With Threaded Surface Roughness in Thermal Elastohydrodynamic Lubrication
Published in Tribology Transactions, 2022
Jiacheng Miao, Xing Du, Chaoyang Li, Xinping Shan, Bingkui Chen
The planetary roller screw mechanism (PRSM) is the most significant transmission component in the electromechanical actuators (EMAs) (1), with characteristics of high loading capacity, high transmission accuracy, compact structure, great heat tolerance, and long service life compared with the ball screw mechanism (2, 3). However, fatigue and wear are the most common failure modes that may cause fatal jamming in EMAs; the high contact stress caused by the external loads on the threaded surface is the common reason for material fatigue. Also, under the high temperature condition, weak thickness of lubrication and decreased lubricant viscosity (4–6) influence not only the transmission jamming but also the sliding-rolling motion within the microcontact area. In thermal elastohydrodynamic lubrication (TEHL), both the local asperities and lubricating film contribute to load sharing of the threaded surfaces, and adhesive wear occurs as one of the main failure modes related to variation of load distribution while the material on the threaded surfaces are cumulatively removed, which reduces transmission accuracy and transmission efficiency and causes device vibration and external friction. Hence, a refined TEHL model for the planetary roller screw mechanism should take frictional heat and thermal conditions into account, as well as thermal loads and surface integrity. The objective of this article is to investigate such a model.
Mechanics of humanoid robot
Published in Advanced Robotics, 2020
Linear drives are alternative to actuate a single-DoF revolute joint by using a four-bar linkage, a ball screw, a planetary roller screw, and so on. Since this approach also enables the spatial separation between the entire drive and the joint, there is the advantage that the movable parts can be lightened. However, the relationship of input and output of such mechanisms is nonlinear which makes joint control more difficult since the nonlinearities must be taken into account. The stiffness of the joint and surrounding structure increases because the leg link and the linear actuator form a closed kinematic chain. However, such mechanisms are more complex in design and manufacturing, and the several bearings may introduce backlash.
Modeling of contact load distribution of planetary threaded roller bearing based on deformation coordination
Published in Mechanics Based Design of Structures and Machines, 2023
Jianan Ni, Jihui Yin, Dandan Li, Jiuqing Liu, Zhijie Xie
Noteworthy, the structural characteristics of PTRB are similar to those of ball screw and planetary roller screw; therefore, the internal contact load distribution characteristics are also fairly similar. Ni and Qi (2018) researched the contact load of ball screw and established a contact load distribution calculation model of ball screw by considering the dimensional error of the ball. They further analyzed the influence of dimensional deviation of the ball and the compound external load on the contact load as well as the fatigue life. Furthermore, Du, Zhang, and Tao (2016) studied the contact deformation of the ball screw according to the Hertz contact theory, and verified the results by performing experiments. Wei and Lai (2011) investigated the kinematics of ball screw by considering the variation of contact angle and deformation. Zhang and Zu (2019) proposed a new method to obtain the friction coefficient of ball screws and verified it by experimental results. Zhou et al. (2019) proposed a method to calculate the effective ball number and the basic static load of ball screw. Jones and Velinsky (2014) established an axial stiffness and load distribution calculation model of planetary roller screw based on direct stiffness method combined with Hertz contact theory. Zhang et al. (2016) established a load distribution model of planetary roller screw based on the relationships between deformation compatibility and force equilibrium by considering machining errors, and proposed the design method for the even distribution of the load. Abevi et al. (2016) studied the static characteristics of inverted planetary roller screw through numerical and experimental studies, established an FE analysis model of planetary roller screw, and investigated the influence of nut shape and bending of the roller on the load distribution. Ma et al. (2015) studied the contact load distribution by considering the roller thread as multiple equivalent balls, assumed that the load distribution on the screw side and the nut side was identical, and further calculated the contact load by using the equilibrium equation of the contact load. Zheng et al. (2020) proposed the equations for calculating the contact load of the adjacent threaded teeth of PTRB based on the Hertzian contact and space matching theories; however, the influence of the bearing mounting method on its contact load was ignored. Du, Chen, and Zheng (2021) calculated the threaded contact load and the fatigue life of planetary roller screw considering the radial load and machining error. As a new type of bearing, the characteristics of PTRB such as contact load, contact deformation, and contact stress need to be further researched.