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Foot terrain impact modeling and motion performance research of hexapod robot based on passive elastic leg 2

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Foot terrain impact modeling and motion performance research...

2nd Spring International Conference on Defence Technology, ICDT 2020

作者： Liu, Y.F. Su, B. Zhou, L. Gao, H.B. Ding, L. Jiang, L. Zou, F.Q. Ma, C.Y. China North Vehicle Research Institute Beijing100072 China Equipment Project Management Center Beijing100072 China State Key Laboratory of Robotics and System Harbin Institute of Technology Harbin150080 China MEMS Center Harbin Institute of Technology Harbin150080 China College of Mechanical Engineering Jiamusi University Jiamusi154007 China

In order to improve the performance of the multi-legged robot, the impact of foot-terrain is an important target to measure the performance of the robot. In order to ensure the compliance contact of foot-terrain for the legged robot, it is essential to add passive spring between the calf and foot. The mechanical structure makes the leg of hexapod robot retractable passive elastic structure. For multi-legged robots with passive elastic legs, the foot-terrain impact model is presented to measure the dynamic performance and provide theoretical support for the low impact force motion planning. The traditional planning method will cause additional impact for the switching case between the swing and stance phase. This paper presents a motion planning method that considers the deformable leg structure and impact performance. The experiments have been carried out, and the results have demonstrated the effectiveness of the foot terrain impact model and motion planning method in comparison with a conventional method. © Published under licence by IOP Publishing Ltd.

关键词： Motion planning

COMSOL-based simulations and experiments on the classifying trajectory of the mixed particles levitated in standing wave field

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COMSOL-based simulations and experiments on the classifying ...

2019 International Congress on Ultrasonics, ICU 2019

作者： Dong, Huijuan Meng, Fanbin Lan, Bin Mu, Guanyu Zhao, Jie School of Mechatronics Engineering Harbin Institute of Technology Hei Longjiang Harbin150001 China State Key Laboratory of Robotics and System Harbin Institute of Technology Harbin150001 China

ISBN: (纸本)9781665407090

In this work, a standing wave acoustic field formed by using two contraposition transducers is used to classify the mixed powder. COMSOL-based simulations reveal the influence of the factors on the drop trajectories of the particles within an acoustic field. Then the experiments are carried out to demonstrate those obtained using COMSOL-based simulations. Finally, the separation experiments of the mixed powder of iron and dioxide silica are achieved, including the mixed powder both in the same diameter and the different diameter respectively. © 2020 Acoustical Society of America.

关键词： Acoustic fields

Application of light diffraction theory to qualify the downstream light field modulation property of mitigated KDP crystals

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arXiv 2020年

作者： Yang, Hao Cheng, Jian Liu, Zhichao Liu, Qi Zhao, Linjie Tan, Chao Wang, Jian Chen, Mingjun State Key Laboratory of Robotics and System Harbin Institute of Technology Harbin150001 China Research Center of Laser Fusion China Academy of Engineering Physics Mianyang621900 China

Micro-milling can effectively remove laser damage sites on a KDP (potassium dihydrogen phosphate) surface and then improve the laser damage resistance of the components. However, the repaired KDP surface could cause light propagating turbulence and downstream light intensification with the potential risk to damage downstream optics. In order to analyze the downstream light field modulation caused by Gaussian mitigation pits on KDP crystals, a computational model of the downstream light diffraction based on the angular spectrum theory and the Gaussian repair contour is established. The results show that the phase offset caused by the repaired surface produces a large light field modulation near the rear KDP surface. The modulation generated in the whole downstream light field is greater than that caused by the amplitude change. Therefore, the phase characteristics of the outgoing light could be suggested as a vital research topic for future research on the downstream light field modulation caused by mitigation contours. Significantly, the experimental results on the downstream light intensity distribution have good agreement with the simulation ones, which proves the validity of the established downstream light diffraction model. The phase characterization of the outgoing light is proposed as an evaluation tool in the repair of KDP crystals. The developed analytical method and numerical discrete algorithm could be also applicable in qualifying the repair quality of other optical components applied in high-power laser systems. Copyright © 2020, The Authors. All rights reserved.

关键词： Diffraction

Bilateral Teleoperation of Wheeled Mobile Robots Subject to Lateral Sliding on Soft Terrains

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Bilateral Teleoperation of Wheeled Mobile Robots Subject to ...

第三十九届中国控制会议

作者： Weihua Li Sanjun Liu Dianbo Ren Jianfeng Wang Haibo Gao School of Automotive Engineering Harbin Institute of Technology(Weihai) State Key Laboratory of Robotics and System Harbin Institute of Technology Shanghai Aerospace Equipments Manufacturer Co Ltd.

With the widespread applications of wheeled mobile robots（WMR） in various fields,new challenges have arisen in terms of designing its control system.A special challenge is the soft terrain which can induce both of the longitudinal slipping and the lateral *** paper proposes a new method for haptic teleoperation control of a WMR with lateral *** this teleoperation system,the linear velocity and the angular velocity of the WMR separately follow the master haptic interface’s *** to the functional benefits of displaying the lateral sliding information as haptic feedback to the operator,the lateral velocity is segregated and only perceived by the human *** the teleoperator for the master robot and the slave WMR is designed based on the passivity *** of the proposed controller demonstrate that this approach results in stable bilateral teleoperation with a satisfactory tracking performance.

关键词： Teleoperation Lateral Sliding Wheeled Mobile Robot

Object-aware hybrid map for indoor robot visual semantic navigation

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Object-aware hybrid map for indoor robot visual semantic nav...

2019 IEEE International Conference on robotics and Biomimetics, ROBIO 2019

作者： Wang, Li Li, Ruifeng Sun, Jingwen Zhao, Lijun Shi, Hezi Seah, Hock Soon Tandianus, Budianto Harbin Institute of Technology State Key Laboratory of Robotics and System Harbin150001 China School of Computer Science and Engineering Nanyang Technological University Nanyang Avenue639798 Singapore

ISBN: (纸本)9781728163215

In order to achieve an intuitive interaction and visual semantic navigation for the indoor robot, we propose a novel object-aware hybrid map. The existing map is usually a metric map, lacking semantics for interaction. We combine objects in the indoor environment with the metric map to constitute a hybrid map. The map consists of a 3D object semantic map and a 2D occupancy grid map, which transfers human commands to the grid map through object semantics, thereby enabling autonomous navigation for the robot. We utilize ORB-SLAM2 for continuous pose estimation and 3D mapping. 2D object detection in key-frames is conducted based on YOLO v3. The object point clouds in multiple perspectives are merged and a 3D bounding box of the object is estimated. These objects construct a 3D semantic map. Furthermore, we project a 3D point cloud map into a 2D plane in order to get an occupancy grid map. Finally, these two maps are combined forming an object-aware hybrid map. We conduct experiments in real environments in order to verify the feasibility and robustness of the hybrid map for robot semantic navigation. © 2019 IEEE.

关键词： Object detection

Domain-invariant similarity activation map contrastive learning for retrieval-based long-term visual localization

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arXiv 2020年

作者： Hu, Hanjiang Wang, Hesheng Liu, Zhe Chen, Weidong Autonomous Robot Lab Department of Automation Key Laboratory of System Control and Information Processing Ministry of Education Shanghai Jiao Tong University Shanghai200240 China The State Key Laboratory of Robotics and System HIT The Department of Computer Science and Technology University of Cambridge United Kingdom

Visual localization is a crucial component in the application of mobile robot and autonomous driving. Image retrieval is an efficient and effective technique in image-based localization methods. Due to the drastic variability of environmental conditions, e.g. illumination, seasonal and weather changes, retrieval-based visual localization is severely affected and becomes a challenging problem. In this work, a general architecture is first formulated probabilistically to extract domain-invariant feature through multi-domain image translation. And then a novel gradient-weighted similarity activation mapping loss (Grad-SAM) is incorporated for finer localization with high accuracy. We also propose a new adaptive triplet loss to boost the contrastive learning of the embedding in a self-supervised manner. The final coarse-to-fine image retrieval pipeline is implemented as the sequential combination of models without and with Grad-SAM loss. Extensive experiments have been conducted to validate the effectiveness of the proposed approach on the CMU-Seasons dataset. The strong generalization ability of our approach is verified on RobotCar dataset using models pre-trained on urban part of CMU-Seasons dataset. Our performance is on par with or even outperforms the state-of-the-art image-based localization baselines in medium or high precision, especially under the challenging environments with illumination variance, vegetation and night-time images. The code and pretrained models are available on https://***/HanjiangHu/DISAM. Copyright © 2020, The Authors. All rights reserved.

关键词： Image retrieval

GRNet: Gridding Residual Network for Dense Point Cloud Completion 16th

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GRNet: Gridding Residual Network for Dense Point Cloud Compl...

16th European Conference on Computer Vision, ECCV 2020

作者： Xie, Haozhe Yao, Hongxun Zhou, Shangchen Mao, Jiageng Zhang, Shengping Sun, Wenxiu State Key Laboratory of Robotics and System Harbin Institute of Technology Harbin China Faculty of Computing Harbin Institute of Technology Harbin China SenseTime Research Shenzhen China Nanyang Technological University Singapore Singapore The Chinese University of Hong Kong Hong Kong SAR China Peng Cheng Laboratory Shenzhen China SenseTime Research Hong Kong SAR China

ISBN: (纸本)9783030585440

Estimating the complete 3D point cloud from an incomplete one is a key problem in many vision and robotics applications. Mainstream methods (e.g., PCN and TopNet) use Multi-layer Perceptrons (MLPs) to directly process point clouds, which may cause the loss of details because the structural and context of point clouds are not fully considered. To solve this problem, we introduce 3D grids as intermediate representations to regularize unordered point clouds and propose a novel Gridding Residual Network (GRNet) for point cloud completion. In particular, we devise two novel differentiable layers, named Gridding and Gridding Reverse, to convert between point clouds and 3D grids without losing structural information. We also present the differentiable Cubic Feature Sampling layer to extract features of neighboring points, which preserves context information. In addition, we design a new loss function, namely Gridding Loss, to calculate the L1 distance between the 3D grids of the predicted and ground truth point clouds, which is helpful to recover details. Experimental results indicate that the proposed GRNet performs favorably against state-of-the-art methods on the ShapeNet, Completion3D, and KITTI benchmarks. © 2020, Springer Nature Switzerland AG.

关键词： Computer vision

Learning to navigate in indoor environments: From memorizing to reasoning

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arXiv 2019年

作者： Ma, Liulong Liu, Yanjie Chen, Jiao Jin, Dong State Key Laboratory of Robotics and System Harbin Institute of Technology China

Autonomous navigation is an essential capability of smart mobility for mobile robots. Traditional methods require the environment map to plan a collision-free path in workspace. Deep reinforcement learning (DRL) is a promising technique to realize the autonomous navigation task without a map, with which deep neural network can fit the mapping from observation to reasonable action through explorations. It should not only memorize the trained target, but more importantly, the planner can reason out the path to unseen goal. We proposed a new motion planner based on deep reinforcement learning that can arrive at new targets that have not been trained before in the indoor environment with RGB image and odometry only. The model has a structure of stacked Long Short-Term memory (LSTM). Finally, experiments were implemented in both simulated and real environments. The source code is available: Https://***/marooncn/navbot. Copyright © 2019, The Authors. All rights reserved.

关键词： Long short-term memory

system Integration and Control Design of a Maglev Platform for Space Vibration Isolation

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arXiv 2019年

作者： Gong, Zhaopei Ding, Liang Yue, Honghao Gao, Haibo Liu, Rongqiang Deng, Zongquan Lu, Yifan State Key Laboratory of Robotics and System Harbin Institute of Technology China

Micro-vibration has been a dominant factor impairing the performance of scientific experiments which are expected to be deployed in a micro-gravity environment such as spacelab. The micro-vibration has serious impact on the scientific experiments requiring quasi-static environment. Therefore, we proposed a maglev vibration isolation platform (MVIP) operating in six degrees of freedom (DOF) to fulfill the environmental requirements. In view of non-contact and large stroke requirement for micro-vibration isolation, an optimization method was utilized to design the actuator. Mathematical models of actuator’s remarkable nonlinearity was established, so that its output can be compensated according to floater’s varying position and system’s performance may be satisfied. Furthermore, aiming to adapt to an energy-limited environment such as spacelab, an optimum allocation scheme was put forward. Considering actuator’s nonlinearity, accuracy and minimum energy-consumption can be obtained simultaneously. In view of operating in six DOF, methods for nonlinear compensation and system decoupling were discussed, the necessary controller were also presented. Simulation and experiments validate system’s performance. With a movement range of 10×10×8 mm and rotations of 200 mrad, the decay ratio of -40 dB/Dec between 1–10 Hz was obtained under close-loop control. Copyright © 2019, The Authors. All rights reserved.

关键词： Actuators