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Many high-end power machines demand greater bearing performance in terms of running speed, precision, reliability, longevity, noise reduction, etc. An ultrasonic bearing based on Near-Field Acoustic Levitation (NFAL) effect is a kind of emerging noncontact gas bearing. Due to its self-aligning capability, the ultrasonic bearing can steadily run at a high speed under high precision. Actuated by piezoelectric...
Many high-end power machines demand greater bearing performance in terms of running speed, precision, reliability, longevity, noise reduction, etc. An ultrasonic bearing based on Near-Field Acoustic Levitation (NFAL) effect is a kind of emerging noncontact gas bearing. Due to its self-aligning capability, the ultrasonic bearing can steadily run at a high speed — tens of thousands of revolutions per...
Drilling & coring has been selected as an effective method of acquiring soil sample in robotic planetary explorations. To avoid serious overload faults, drilling states should be monitored online and be tuned in a reasonable range. Herein, a novel flexible tube coring (FTC) method is adopted in China lunar exploration mission. To verify the proposed FTC method and acquire useful drilling states...
A novel active gravity compensation concept is proposed to simulate space on-orbit microgravity environments for free-flying robots on ground. Here, robots are suspended by active-controlled motion path tracking mechanisms through wires to compensate for gravitational forces. Based on the concept, an experimental test bed was designed and fabricated in laboratory to study on-ground kinematic and dynamic...
An underactuated robotic finger is proposed and studied for capturing non-cooperative objects, featuring an underactuated rigid-mechanism that can brake residual motion of non-cooperative targets. The finger consists of three joints driven by two actuators, and a set of one-input-two-output planetary gears is introduced to realize force transmission by using the ring gear and the planetary carrier...
Drilling & coring is considered as an effective way to acquire deep sample on the moon. Since the lunar regolith environment in depth is unknown, sampling drill should be developed to adapt to the undetermined drilling medium on the moon. Once mechanical system of sampling robot was finished, control strategy is a key to realize the high-efficiency drilling process. Since composition of lunar...
The second step for lunar exploration of China has been completed already, the probe “Chang'e-3” successfully landed on the moon, including a lander and a lunar rover. The third step of the project is to achieve automated sampling of lunar regolith through a drilling and coring device. On the moon, lunar regolith and lunar rock may be encountered randomly along the longitudinal direction. Due to the...
Different from the traditional using method of one-input-one-output in planetary gear reducer, a concept of one-input-two-output is proposed to drive an underactuated finger. A finger consisting of three degrees of freedom, is driven by two actuators. MP joint is driven by one actuator while PIP and DIP joints are driven by another actuator with power distribution by a planetary gear reducer. When...
Rotary-percussive Drill (RPD) has been widely employed in extraterrestrial exploration as a main drilling and sampling device. Percussive mechanism, as an inevitable part of RPD, is commonly utilized to exert percussion onto drill stem to improve drilling performance once hard rock is encountered. However, since driving resource provided by the probe is limited in lunar exploration, outputs of percussive...
Drill sampling has been widely employed in extraterrestrial exploration. Since the extraterrestrial environment is uncertain and different from that on the earth, the extraterrestrial drill sampling mission is at risk of failure. Therefore, the principle of drilling and coring in extraterrestrial environment and the structural parameters of special drilling tools should be tested and verified. In...
Mechanical models are developed to analyze the effect of rim radius on motion performance of lunar rover wheel, which is useful for designing wheel configuration, vehicle simulation and dynamic analysis of lunar rover. Based on the terramechanics, shear force and bulldozing resistance acting on the wheel are investigated. And the quantitative relation among rim radius, drawbar pull, driving torque...
The wheel slip ratio is an important state variable in terramechanics research and the control of planetary rovers. Definitions of the slip ratio for a wheel with lugs and methods of estimating it for all wheels onboard have seldom been attempted. This paper presents several definitions for the slip ratio of a lugged wheel, which can be interconverted by altering the shearing radius. Equations for...
In order to analyze the performance of lunar rover, draw bar pull and motion resistance are analyzed in this paper based on terramechanics. The relationships between configuration parameters (like wheel width, wheel bases et al.) and mobility performance parameters are obtained from the analysis. Meanwhile, the sensitive factors of the motion resistance are found. Then main performance evaluation...
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