As one of the prominent landforms in the Zhurong landing region,mesas are geological features with flat tops and steep marginal cliffs.The mesas are widely distributed along the dichotomy boundary.There are various in...As one of the prominent landforms in the Zhurong landing region,mesas are geological features with flat tops and steep marginal cliffs.The mesas are widely distributed along the dichotomy boundary.There are various interpreted origins proposed for the mesas,such as the erosion of sedimentary layers,tuyas eruptions,or surface collapse due to the catastrophic release of groundwater.We investigate the detailed morphological characteristics of the mesas on the Late Hesperian Lowland unit within the Utopia Planitia.We observe morphological evidence for both the ice-bearing interior mesas and the sedimentary origin,including(1)small pits on the crater wall and mesa cliff formed by the release of volatiles like ice;(2)lobate flows at the base of mesas formed by the melting of subsurface ice;(3)layered mesas indicating sedimentary origin;(4)grooves on the top surface of mesas formed by the volumetric compaction of sedimentary deposits.The results indicate that the mesas in the study area are formed by the erosion of sedimentary layers and representative of the Noachian oceanic sediments.We propose an evolutionary model for the mesas.This study will provide some insights into future research of ancient ocean hypothesis of Mars and interesting targets for the exploration of the Zhurong rover.展开更多
Space manipulators play an important role in the on-orbit services and planetary surface operation.In the extreme environment of space,space manipulators are susceptible to a variety of unknown disturbances.How to hav...Space manipulators play an important role in the on-orbit services and planetary surface operation.In the extreme environment of space,space manipulators are susceptible to a variety of unknown disturbances.How to have a resilient guarantee in failure or disturbance is the core capability of its future development.Compared with traditional motion planning,learning-based motion planning has gradually become a hot spot in current research.However,no matter what kind of research ideas,the single robotic manipulator is studied as an independent agent,making it unable to provide sufficient flexibility under conditions such as external force disturbance,observation noise,and mechanical failure.Therefore,this paper puts forward the idea of“discretization of the traditional single manipulator”.Different discretization forms are given through the analysis of the multi-degree-of-freedom single-manipulator joint relationship,and a single-manipulator representation composed of multiple new subagents is obtained.Simultaneously,to verify the ability of the new multiagent representation to deal with interference,we adopted a centralized multiagent reinforcement learning framework.The influence of the number of agents and communication distances on learning-based planning results is analyzed in detail.In addition,by imposing joint locking failures on the manipulator and introducing observation and action interference,it is verified that the“multiagent robotic manipulator”obtained after discretization has stronger antidisturbance resilient capability than the traditional single manipulator.展开更多
基金supported by the Strategic Priority Research Program of the Chinese Academy of Sciences(No.XDB 41000000)the National Natural Science Foundation of China(Nos.42273041,41830214)the Preresearch Project on Civil Aerospace Technologies of CNSA(No.D020101)。
文摘As one of the prominent landforms in the Zhurong landing region,mesas are geological features with flat tops and steep marginal cliffs.The mesas are widely distributed along the dichotomy boundary.There are various interpreted origins proposed for the mesas,such as the erosion of sedimentary layers,tuyas eruptions,or surface collapse due to the catastrophic release of groundwater.We investigate the detailed morphological characteristics of the mesas on the Late Hesperian Lowland unit within the Utopia Planitia.We observe morphological evidence for both the ice-bearing interior mesas and the sedimentary origin,including(1)small pits on the crater wall and mesa cliff formed by the release of volatiles like ice;(2)lobate flows at the base of mesas formed by the melting of subsurface ice;(3)layered mesas indicating sedimentary origin;(4)grooves on the top surface of mesas formed by the volumetric compaction of sedimentary deposits.The results indicate that the mesas in the study area are formed by the erosion of sedimentary layers and representative of the Noachian oceanic sediments.We propose an evolutionary model for the mesas.This study will provide some insights into future research of ancient ocean hypothesis of Mars and interesting targets for the exploration of the Zhurong rover.
基金the Young Elite Scientists Sponsorship Program by CAST(grant number:2021QNRC001)Natural Science Foundation of Heilongjiang Province of China(grant number:YQ2022F012)+1 种基金Siyuan Alliance Open ended Fund(grant number:HTKJ2022KL012003)the Fundamental Research Funds for the Central Universities(grant number:HIT.OCEF.2023010).
文摘Space manipulators play an important role in the on-orbit services and planetary surface operation.In the extreme environment of space,space manipulators are susceptible to a variety of unknown disturbances.How to have a resilient guarantee in failure or disturbance is the core capability of its future development.Compared with traditional motion planning,learning-based motion planning has gradually become a hot spot in current research.However,no matter what kind of research ideas,the single robotic manipulator is studied as an independent agent,making it unable to provide sufficient flexibility under conditions such as external force disturbance,observation noise,and mechanical failure.Therefore,this paper puts forward the idea of“discretization of the traditional single manipulator”.Different discretization forms are given through the analysis of the multi-degree-of-freedom single-manipulator joint relationship,and a single-manipulator representation composed of multiple new subagents is obtained.Simultaneously,to verify the ability of the new multiagent representation to deal with interference,we adopted a centralized multiagent reinforcement learning framework.The influence of the number of agents and communication distances on learning-based planning results is analyzed in detail.In addition,by imposing joint locking failures on the manipulator and introducing observation and action interference,it is verified that the“multiagent robotic manipulator”obtained after discretization has stronger antidisturbance resilient capability than the traditional single manipulator.
