A novel reconfigurable tracked robot based on four-link mechanism was proposed and released for the complicated terrain environment. This robot was modularly designed and developed, which is composed of one suspension...A novel reconfigurable tracked robot based on four-link mechanism was proposed and released for the complicated terrain environment. This robot was modularly designed and developed, which is composed of one suspension and one pair of symmetrical deployed reconfigurable track modules. This robot can implement multiple locomotion configurations by changing the track configuration, and the geometric theory analysis shows that the track length keeps constant during the process of track reconfiguration. Furthermore, a parameterized geometric model of the robot was established to analyze the kinematic performance of the robot while overcoming various obstacles. To investigate the feasibility and correctness of design theory and robot scheme, an example robot was designed to climb 45° slopes and 200 mm steps, and a group of design parameters of the robot were determined. Finally, A prototype of this robot was developed, and the test results show that the robot own powerful mobility and obstacle overcoming performance, for example, running across obstacle like mantis, extending to stride over entrenchment, standing up to elevate height, and going ahead after overturn.展开更多
Self-healing materials have attracted considerable attention because of their improved safety, lifetime, energy efficiency and environmental impact. Supramolecular interactions have been extensively considered in the ...Self-healing materials have attracted considerable attention because of their improved safety, lifetime, energy efficiency and environmental impact. Supramolecular interactions have been extensively considered in the field of self-healing materials due to their excellent reversibility and sensitive responsiveness to environmental stimuli. However,development of a polymeric material with good mechanical performance as well as self-healing capacity is very challenging. In this study, we report a robust self-healing polyurethane(PU) elastomer polypropylene glycol-2-amino-5-(2-hydroxyethyl)-6-methylpyrimidin-4-ol(PPG-mUPy) by integrating ureidopyrimidone(UPy) motifs with a PPG segment with a well-defined architecture and microphase morphology.To balance the self-healing capacity and mechanical performance, a thermal-triggered switch of H-bonding is introduced. The quadruple H-bonded UPy dimeric moieties in the backbone induce phase separation to form a hard domain as well as enable further aggregation into microcrystals by virtue of the stacking interactions, which are stable in ambient temperature. This feature endows the PU with high mechanical strength. Meanwhile, a high healing efficiency can be realized, when the reversibility of the H-bond was unlocked from the stacking at higher temperature. An optimized sample PPG1000-mUPy50%with a good balance of mechanical performance(20.62 MPa of tensile strength) and healing efficiency(93% in tensile strength) was achieved. This strategy will provide a new idea for developing robust self-healing polymers.展开更多
This paper presents the idea of constructing reconfigurable limbs by integrating metamorphic linkages as subchains.The planar five-bar metamorphic linkages that have three phases resulting from locking of motors are c...This paper presents the idea of constructing reconfigurable limbs by integrating metamorphic linkages as subchains.The planar five-bar metamorphic linkages that have three phases resulting from locking of motors are considered.Under the assumption that the constraint exerted by the reconfigurable limb can switch between no constraint,a constraint force,and a constraint couple,the output motions of the metamorphic linkage in its two planar four-bar linkage phases are identified.By adding an appropriate joint to planar four-bar linkages with translational output,four planar five-bar linkages that can be employed in the construction of reconfigurable limbs are enumerated.Serial chains that can provide a constraint couple and a constraint force are synthesized based on screw theory.Reconfigurable limbs that have three configurations associated with the three distinct phases of the metamorphic linkages are assembled with planar five-bar metamorphic linkages and serial chains with four degrees of freedom.A class of reconfigurable parallel mechanisms are constructed by connecting a moving platform and a base with three identical reconfigurable limbs.The degrees of freedom of the reconfigurable parallel mechanism in different configurations with the metamorphic linkages in different phases are given.Finally,the actuation scheme for this kind of mechanisms is addressed.展开更多
基金Project(2007AA04Z256) supported by the National High Technology Research and Development Program of China
文摘A novel reconfigurable tracked robot based on four-link mechanism was proposed and released for the complicated terrain environment. This robot was modularly designed and developed, which is composed of one suspension and one pair of symmetrical deployed reconfigurable track modules. This robot can implement multiple locomotion configurations by changing the track configuration, and the geometric theory analysis shows that the track length keeps constant during the process of track reconfiguration. Furthermore, a parameterized geometric model of the robot was established to analyze the kinematic performance of the robot while overcoming various obstacles. To investigate the feasibility and correctness of design theory and robot scheme, an example robot was designed to climb 45° slopes and 200 mm steps, and a group of design parameters of the robot were determined. Finally, A prototype of this robot was developed, and the test results show that the robot own powerful mobility and obstacle overcoming performance, for example, running across obstacle like mantis, extending to stride over entrenchment, standing up to elevate height, and going ahead after overturn.
基金financially supported by the National Natural Science Foundation of China(51773131,51811530149and 51721091)the International S&T Cooperation Project of Sichuan Province(2017HH0034)
文摘Self-healing materials have attracted considerable attention because of their improved safety, lifetime, energy efficiency and environmental impact. Supramolecular interactions have been extensively considered in the field of self-healing materials due to their excellent reversibility and sensitive responsiveness to environmental stimuli. However,development of a polymeric material with good mechanical performance as well as self-healing capacity is very challenging. In this study, we report a robust self-healing polyurethane(PU) elastomer polypropylene glycol-2-amino-5-(2-hydroxyethyl)-6-methylpyrimidin-4-ol(PPG-mUPy) by integrating ureidopyrimidone(UPy) motifs with a PPG segment with a well-defined architecture and microphase morphology.To balance the self-healing capacity and mechanical performance, a thermal-triggered switch of H-bonding is introduced. The quadruple H-bonded UPy dimeric moieties in the backbone induce phase separation to form a hard domain as well as enable further aggregation into microcrystals by virtue of the stacking interactions, which are stable in ambient temperature. This feature endows the PU with high mechanical strength. Meanwhile, a high healing efficiency can be realized, when the reversibility of the H-bond was unlocked from the stacking at higher temperature. An optimized sample PPG1000-mUPy50%with a good balance of mechanical performance(20.62 MPa of tensile strength) and healing efficiency(93% in tensile strength) was achieved. This strategy will provide a new idea for developing robust self-healing polymers.
基金supported by the National Natural Science Foundation of China(Grant Nos.51075025,51175029)Beijing Natural Science Foundation of China(Grant No.3132019)the Program for New Century Excellent Talents in University of China(Grant No.NCET-12-0769)
文摘This paper presents the idea of constructing reconfigurable limbs by integrating metamorphic linkages as subchains.The planar five-bar metamorphic linkages that have three phases resulting from locking of motors are considered.Under the assumption that the constraint exerted by the reconfigurable limb can switch between no constraint,a constraint force,and a constraint couple,the output motions of the metamorphic linkage in its two planar four-bar linkage phases are identified.By adding an appropriate joint to planar four-bar linkages with translational output,four planar five-bar linkages that can be employed in the construction of reconfigurable limbs are enumerated.Serial chains that can provide a constraint couple and a constraint force are synthesized based on screw theory.Reconfigurable limbs that have three configurations associated with the three distinct phases of the metamorphic linkages are assembled with planar five-bar metamorphic linkages and serial chains with four degrees of freedom.A class of reconfigurable parallel mechanisms are constructed by connecting a moving platform and a base with three identical reconfigurable limbs.The degrees of freedom of the reconfigurable parallel mechanism in different configurations with the metamorphic linkages in different phases are given.Finally,the actuation scheme for this kind of mechanisms is addressed.
