In order to improve the traction performance of the micro-tiller wheel on the paddy soil surface, a bionic paddy wheel was designed with a cattle hoof as the bionic prototype, and its diameter and wheel width were 0.46 m and 0.08 m, respectively. The traction performance test was carried out in a soil bin test-bed with a moisture content of 36 %. The vertical loads were 82.57 N, 131.40 N and 179.42 N, respectively. The driving speeds were 0.3 m/s, 0.5 m/s and 0.7 m/s, respectively. The drawbar pull was in the range of 10 – 120 N. The results showed that at the driving speed of 0.7 m/s, with the increase of the vertical load, the driving torque and the drawbar pull are increasing. The vertical load has a significant effect on the change of driving torque and maximum drawbar pull. Under the vertical load of 179.42 N and different driving speeds, when the slip ratio is less than 0.37, the efficiency coefficient begins to grow rapidly, and the greater the driving speed is, the greater the growth rate is. When the slip ratio is about 0.37, the efficiency coefficient reaches the maximum and then begins to decrease. Driving speed has a significant effect on the maximum efficiency coefficient of wheels. This paper can provide a reference for the traction performance of the micro-tiller wheel on the paddy soil surface and the design of the new bionic paddy wheel.
{"title":"Design and Traction Performance Test of Bionic Paddy Wheel Based on Cattle Hoof","authors":"Lan Li, Jing Li, B. Xie, Fei Lin, Long Xue","doi":"10.56884/otpf6196","DOIUrl":"https://doi.org/10.56884/otpf6196","url":null,"abstract":"In order to improve the traction performance of the micro-tiller wheel on the paddy soil surface, a bionic paddy wheel was designed with a cattle hoof as the bionic prototype, and its diameter and wheel width were 0.46 m and 0.08 m, respectively. The traction performance test was carried out in a soil bin test-bed with a moisture content of 36 %. The vertical loads were 82.57 N, 131.40 N and 179.42 N, respectively. The driving speeds were 0.3 m/s, 0.5 m/s and 0.7 m/s, respectively. The drawbar pull was in the range of 10 – 120 N. The results showed that at the driving speed of 0.7 m/s, with the increase of the vertical load, the driving torque and the drawbar pull are increasing. The vertical load has a significant effect on the change of driving torque and maximum drawbar pull. Under the vertical load of 179.42 N and different driving speeds, when the slip ratio is less than 0.37, the efficiency coefficient begins to grow rapidly, and the greater the driving speed is, the greater the growth rate is. When the slip ratio is about 0.37, the efficiency coefficient reaches the maximum and then begins to decrease. Driving speed has a significant effect on the maximum efficiency coefficient of wheels. This paper can provide a reference for the traction performance of the micro-tiller wheel on the paddy soil surface and the design of the new bionic paddy wheel.","PeriodicalId":447600,"journal":{"name":"Proceedings of the 11th Asia-Pacific Regional Conference of the ISTVS","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2022-10-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"122479436","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
V. Vantsevich, D. Gorsich, Jesse R. Paldan, Jordan Whitson, Brian Butrico, O. Sapunkov
A vehicle’s dynamic factor characterizes the potential that can be created by the powertrain that may be utilized to overcome the rolling resistance, grade resistance, and accelerate the vehicle. The dynamic factor is commonly given as a function of the vehicle's theoretical velocity and computed using the powertrain characteristics without taking into account the effect of the driveline configuration which can impact the tire slippages and vehicle’s actual velocity. The velocity reduction due to tire slip can considerably impact the vehicle speed for off-road vehicles operating with large traction requirements. In this paper, a new approach to interpretation of the dynamic factor is presented which is based on the vehicle's actual velocity and driveline characteristics. The computation of the actual velocity accounts for the individual tire slippages of vehicles with multiple driving axles, which is influenced by the ground condition and power splitting characteristics of the driveline. A comparison of the conventional and proposed approach is given for a 4x4 off-road vehicle. A set of factors for vehicle design are proposed based on integral qualities of the ideal and actual dynamic factor to characterize the combined influence of the transmission and driveline system to utilize the engine power for vehicle acceleration performance.
{"title":"Vehicle Dynamic Factor Characterized by Actual Velocity and Combined Influence of the Transmission and Driveline System","authors":"V. Vantsevich, D. Gorsich, Jesse R. Paldan, Jordan Whitson, Brian Butrico, O. Sapunkov","doi":"10.56884/arao9883","DOIUrl":"https://doi.org/10.56884/arao9883","url":null,"abstract":"A vehicle’s dynamic factor characterizes the potential that can be created by the powertrain that may be utilized to overcome the rolling resistance, grade resistance, and accelerate the vehicle. The dynamic factor is commonly given as a function of the vehicle's theoretical velocity and computed using the powertrain characteristics without taking into account the effect of the driveline configuration which can impact the tire slippages and vehicle’s actual velocity. The velocity reduction due to tire slip can considerably impact the vehicle speed for off-road vehicles operating with large traction requirements. In this paper, a new approach to interpretation of the dynamic factor is presented which is based on the vehicle's actual velocity and driveline characteristics. The computation of the actual velocity accounts for the individual tire slippages of vehicles with multiple driving axles, which is influenced by the ground condition and power splitting characteristics of the driveline. A comparison of the conventional and proposed approach is given for a 4x4 off-road vehicle. A set of factors for vehicle design are proposed based on integral qualities of the ideal and actual dynamic factor to characterize the combined influence of the transmission and driveline system to utilize the engine power for vehicle acceleration performance.","PeriodicalId":447600,"journal":{"name":"Proceedings of the 11th Asia-Pacific Regional Conference of the ISTVS","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2022-10-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"114039976","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
It is commonly known that the dynamic behavior of a vibratory drum of a soil compaction machine changes with soil stiffness. Although real-time monitoring techniques of compaction quality by measuring the acceleration of the vibratory drum have already been put into practice use, their applicability depends on the soil type and condition. In this study, to extend the range of applicability and improve accuracy, we propose a deep learning-based technique that allows the regression estimation of soil stiffness from the acceleration responses of a vibration drum. To collect a large amount of noise-free training data, the acceleration responses of a vibratory drum were simulated by numerically solving the equations of the motion mass-spring-damper system. We also conducted a field experiment to verify the proposed technique. The experimental results show that the estimated values of soil stiffness correlate with the measured values, with the correlation coefficient of approximately 0.79. Thus, the proposed method has potential as a new real-time monitoring technique for soil compaction quality.
{"title":"Soil Compaction Monitoring Technique Using Deep Learning","authors":"S. Teramoto, Taizo Kobayashi","doi":"10.56884/zbsa8929","DOIUrl":"https://doi.org/10.56884/zbsa8929","url":null,"abstract":"It is commonly known that the dynamic behavior of a vibratory drum of a soil compaction machine changes with soil stiffness. Although real-time monitoring techniques of compaction quality by measuring the acceleration of the vibratory drum have already been put into practice use, their applicability depends on the soil type and condition. In this study, to extend the range of applicability and improve accuracy, we propose a deep learning-based technique that allows the regression estimation of soil stiffness from the acceleration responses of a vibration drum. To collect a large amount of noise-free training data, the acceleration responses of a vibratory drum were simulated by numerically solving the equations of the motion mass-spring-damper system. We also conducted a field experiment to verify the proposed technique. The experimental results show that the estimated values of soil stiffness correlate with the measured values, with the correlation coefficient of approximately 0.79. Thus, the proposed method has potential as a new real-time monitoring technique for soil compaction quality.","PeriodicalId":447600,"journal":{"name":"Proceedings of the 11th Asia-Pacific Regional Conference of the ISTVS","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2022-10-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"126794046","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
B. Xing, Bo Su, Lei Jiang, Yufei Liu, Zhirui Wang, Jianxin Zhao, Tianqi Qiu
Legged robots promise an advantage over traditional wheeled systems, however, most legged robots are still confined to structured and flat environments. In this paper, we present a motion planner for the perceptive rough-terrain locomotion with quadruped robots. One of the main reasons for this is the difficulty in planning complex whole-body motions while taking into account the terrain conditions. This problem is very high-dimensional as it considers the robots dynamics together with the terrain model in a suitable problem formulation. In this work, we propose a novel trajectory and foothold optimization method that plans dynamically both foothold locations and motions (coupled planning). It jointly optimizes body motion, step duration and foothold selection, considering the terrain topology. Our model predictive controller tracks compliantly trunk motions while avoiding slippage. We test our method and comparative evaluations over a set of terrains of progressively increasing difficulty. To this end, we present a novel pose optimization approach that enables the robot to climb over significant obstacles. We experimentally validate our approach with the quadrupedal robot Panda5 autonomously traversing obstacles such steps, inclines, and stairs. The locomotion planner re-plans the motion at every step to cope with disturbances and dynamic environments.
{"title":"Perceptive Locomotion of Legged Robot Coupling Model Predictive Control and Terrain Mapping","authors":"B. Xing, Bo Su, Lei Jiang, Yufei Liu, Zhirui Wang, Jianxin Zhao, Tianqi Qiu","doi":"10.56884/kpgl5403","DOIUrl":"https://doi.org/10.56884/kpgl5403","url":null,"abstract":"Legged robots promise an advantage over traditional wheeled systems, however, most legged robots are still confined to structured and flat environments. In this paper, we present a motion planner for the perceptive rough-terrain locomotion with quadruped robots. One of the main reasons for this is the difficulty in planning complex whole-body motions while taking into account the terrain conditions. This problem is very high-dimensional as it considers the robots dynamics together with the terrain model in a suitable problem formulation. In this work, we propose a novel trajectory and foothold optimization method that plans dynamically both foothold locations and motions (coupled planning). It jointly optimizes body motion, step duration and foothold selection, considering the terrain topology. Our model predictive controller tracks compliantly trunk motions while avoiding slippage. We test our method and comparative evaluations over a set of terrains of progressively increasing difficulty. To this end, we present a novel pose optimization approach that enables the robot to climb over significant obstacles. We experimentally validate our approach with the quadrupedal robot Panda5 autonomously traversing obstacles such steps, inclines, and stairs. The locomotion planner re-plans the motion at every step to cope with disturbances and dynamic environments.","PeriodicalId":447600,"journal":{"name":"Proceedings of the 11th Asia-Pacific Regional Conference of the ISTVS","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2022-10-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"121279215","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
The research of track-soil interaction modeling over soft deformable terrains is an important direction in terramechanics. Wong proposed a general theory of skidsteering tracked vehicle model by focusing on the trackterrain interaction of the bottom surface of tracks while neglecting the resistance and the bulldozing effect contributed by the laterally accumulated soil to the side of tracked vehicle. The phenomenon becomes nonnegligible and sometimes significant during small radius turn maneuvers, which are quite common in robot motion planning. In order to investigate this quite important and complicated interaction process and establish a complete track-terrain interaction model, we build an instrumented experimental platform. In this platform, the RGB-D information for deformable terrains can be measured and analyzed to obtain several important soil parameters in real-time, including the contours of the soils in contact with the supporting wheels, and the cross-section shapes of the accumulated soils. We apply image segmentation, mapping depth images, point cloud drawing and postprocessing to divide the tracked vehicle and the soil in point cloud images. We reconstruct the morphology of the soil accumulated on the side of vehicles during small radius steering maneuvers, and then obtain aforementioned parameters in order to explain the bulldozing effect.
{"title":"Experimental Study of Track-Soil Interactions of the Steering Performance of Tracked Robots over Soft Deformable Terrains","authors":"Qiaowen Wang, Zhenzhong Jia","doi":"10.56884/vgtd2054","DOIUrl":"https://doi.org/10.56884/vgtd2054","url":null,"abstract":"The research of track-soil interaction modeling over soft deformable terrains is an important direction in terramechanics. Wong proposed a general theory of skidsteering tracked vehicle model by focusing on the trackterrain interaction of the bottom surface of tracks while neglecting the resistance and the bulldozing effect contributed by the laterally accumulated soil to the side of tracked vehicle. The phenomenon becomes nonnegligible and sometimes significant during small radius turn maneuvers, which are quite common in robot motion planning. In order to investigate this quite important and complicated interaction process and establish a complete track-terrain interaction model, we build an instrumented experimental platform. In this platform, the RGB-D information for deformable terrains can be measured and analyzed to obtain several important soil parameters in real-time, including the contours of the soils in contact with the supporting wheels, and the cross-section shapes of the accumulated soils. We apply image segmentation, mapping depth images, point cloud drawing and postprocessing to divide the tracked vehicle and the soil in point cloud images. We reconstruct the morphology of the soil accumulated on the side of vehicles during small radius steering maneuvers, and then obtain aforementioned parameters in order to explain the bulldozing effect.","PeriodicalId":447600,"journal":{"name":"Proceedings of the 11th Asia-Pacific Regional Conference of the ISTVS","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2022-10-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"114341361","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Kaidi Zhang, Yun-qing Zhang, Junwei Shi, Weili Kong
Apollo Lunar Rover Vehicle (LRV) used wire mesh wheels to adapt to the loose and soft soil conditions on the lunar surface, aimed to meet the mobility performance of LRV on the moon. Therefore, it is of great significance to study the wheel-soil interaction characteristics of the wire mesh wheel to improve the maneuverability and traction performance of LRVs. This paper proposed a coupled analysis method of wire mesh wheel-soil based on the DEM-FEM method. Firstly, a lunar terrain DEM model was established, which conforming to the physical characteristics of the lunar soil. Then, a FEM model of the flexible wire mesh wheel with large deformation characteristics was developed, which was verified by stiffness tests. In addition, the mobility performance of the wheel model developed were studied under different slip rates and sideslip angles, respectively. The simulation results were compared and validated with NASA experiment data. The results can provide technical support for the coupling simulation of wire mesh wheels and the traction characteristics of LRV.
{"title":"Modeling of Lunar Rover Vehicle Wheel-Soil Interaction Using Fem-Dem Method","authors":"Kaidi Zhang, Yun-qing Zhang, Junwei Shi, Weili Kong","doi":"10.56884/otlt5367","DOIUrl":"https://doi.org/10.56884/otlt5367","url":null,"abstract":"Apollo Lunar Rover Vehicle (LRV) used wire mesh wheels to adapt to the loose and soft soil conditions on the lunar surface, aimed to meet the mobility performance of LRV on the moon. Therefore, it is of great significance to study the wheel-soil interaction characteristics of the wire mesh wheel to improve the maneuverability and traction performance of LRVs. This paper proposed a coupled analysis method of wire mesh wheel-soil based on the DEM-FEM method. Firstly, a lunar terrain DEM model was established, which conforming to the physical characteristics of the lunar soil. Then, a FEM model of the flexible wire mesh wheel with large deformation characteristics was developed, which was verified by stiffness tests. In addition, the mobility performance of the wheel model developed were studied under different slip rates and sideslip angles, respectively. The simulation results were compared and validated with NASA experiment data. The results can provide technical support for the coupling simulation of wire mesh wheels and the traction characteristics of LRV.","PeriodicalId":447600,"journal":{"name":"Proceedings of the 11th Asia-Pacific Regional Conference of the ISTVS","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2022-10-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"131692833","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Mengyang Li, Xinsheng Wang, Xiyue Wang, Shuang Liu
With the rapid development of mobile robot, the premise of all decisions and planning is to perceive the surrounding environment, especially in complex environments such as wild and mountainous areas. The mainstream Simultaneous Localization and Mapping (SLAM) algorithm Lightweight and Ground-Optimized Lidar Odometry and Mapping (LeGO-LOAM) can be well adapted to this complex environment, but it does not take into account the motion compensation of the point cloud, which leads to a decrease in perception accuracy. LeGO-LOAM adopts the way of feature point and feature point matching for posture estimation. Due to the vertical launch angle of every scanning laser radar being fixed, the radar motion will lead to distortion between the matching feature points, which can cause incorrect pose estimation. Therefore, based on LeGO-LOAM, this paper proposes a motion compensation algorithm (LeGO-LOAM-MC). Compared with the current mainstream of laser slam algorithm LeGO-LOAM, the result shows LeGO-LOAM-MC has a smoother mapping effect, smaller path drift, the maximum error is reduced by 29.1%, the mean error is reduced by 31.0%, the median error is reduced by 31.3%, the standard deviation is reduced by 37.0%, the root mean square error is reduced by 32.1%, and the sum of squares due to error is reduced by 53.9%. The experimental results show the superior performance of the proposed algorithm.
随着移动机器人的快速发展，所有决策和规划的前提都是对周围环境的感知，特别是在野外、山区等复杂环境中。主流的SLAM (Simultaneous Localization and Mapping)算法light and Ground-Optimized Lidar Odometry and Mapping (LeGO-LOAM)可以很好地适应这种复杂的环境，但它没有考虑点云的运动补偿，导致感知精度下降。LeGO-LOAM采用特征点和特征点匹配的方式进行姿态估计。由于每个扫描激光雷达的垂直发射角度是固定的，雷达运动将导致匹配特征点之间的畸变，从而导致不正确的姿态估计。因此，本文提出了一种基于LeGO-LOAM的运动补偿算法(LeGO-LOAM- mc)。与当前主流激光slam算法LeGO-LOAM相比，结果表明，LeGO-LOAM- mc映射效果更平滑，路径漂移更小，最大误差减小29.1%，平均误差减小31.0%，中位数误差减小31.3%，标准差减小37.0%，均方根误差减小32.1%，误差平方和减小53.9%。实验结果表明，该算法具有良好的性能。
{"title":"An Improved Simultaneous Localization and Mapping Method Base on LeGO-LOAM and Motion Compensation","authors":"Mengyang Li, Xinsheng Wang, Xiyue Wang, Shuang Liu","doi":"10.56884/hhvh4446","DOIUrl":"https://doi.org/10.56884/hhvh4446","url":null,"abstract":"With the rapid development of mobile robot, the premise of all decisions and planning is to perceive the surrounding environment, especially in complex environments such as wild and mountainous areas. The mainstream Simultaneous Localization and Mapping (SLAM) algorithm Lightweight and Ground-Optimized Lidar Odometry and Mapping (LeGO-LOAM) can be well adapted to this complex environment, but it does not take into account the motion compensation of the point cloud, which leads to a decrease in perception accuracy. LeGO-LOAM adopts the way of feature point and feature point matching for posture estimation. Due to the vertical launch angle of every scanning laser radar being fixed, the radar motion will lead to distortion between the matching feature points, which can cause incorrect pose estimation. Therefore, based on LeGO-LOAM, this paper proposes a motion compensation algorithm (LeGO-LOAM-MC). Compared with the current mainstream of laser slam algorithm LeGO-LOAM, the result shows LeGO-LOAM-MC has a smoother mapping effect, smaller path drift, the maximum error is reduced by 29.1%, the mean error is reduced by 31.0%, the median error is reduced by 31.3%, the standard deviation is reduced by 37.0%, the root mean square error is reduced by 32.1%, and the sum of squares due to error is reduced by 53.9%. The experimental results show the superior performance of the proposed algorithm.","PeriodicalId":447600,"journal":{"name":"Proceedings of the 11th Asia-Pacific Regional Conference of the ISTVS","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2022-10-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"124364467","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
The Hohenheim Tire Model (HTM) was developed and validated at the University of Hohenheim. It simulates the specific behavior of large-volume agricultural tires and is used in conjunction with multi-body models of tractors and other agricultural machines. Special focus is placed on driving dynamics and comfort. Currently the HTM is being expanded for implementation on soft soils. Therefor the soil's shear response using Bevameter tests and the relationship traction-wheel slip using a single wheel tester are investigated. In field tests, the effect of shear rate on soil mechanical parameters was examined. The shear device of the Bevameter was used to conduct experiments in a soil bin with silty loam at eight shear rates and five vertical loads. The Mohr-Coulomb failure criterion was calculated and the measured values were fitted to the Wong-Preston and the Janosi-Hanamoto approaches. The shear stress-shear displacement curves show two different behaviors with respect to shear rate. At high shear rates, the shear stress reaches a peak and then drops to a residual value, which is typical for cohesive soils. At low shear rates, the trend of the curves is exponential, which is typical for granular soils. The cohesion and angle of internal friction values are comparable to those from literature. The angle of internal friction has no correlation with shear rate while the cohesion shows a low correlation. Traction-wheel slip curves for the tractor tire 480/70 R24 with two tire loads (17 and 22 kN) and at 2 km∙h-1 were measured under identical conditions as the shear experiments. For the higher tire load, there is a tendency toward a larger tractive force. The curves of both wheel loads have equal gross traction coefficients. For the prediction of the traction force, the parameters obtained in the shear tests and the method of Wong and Preston-Thomas are used.
{"title":"Investigation of the Shear Stress Dynamics on Silty Loam Soil and Measurement of Traction-Wheel Slip Relationship of a Tractor Tire","authors":"Cesar Arevalo, S. Böttinger","doi":"10.56884/wvqn3391","DOIUrl":"https://doi.org/10.56884/wvqn3391","url":null,"abstract":"The Hohenheim Tire Model (HTM) was developed and validated at the University of Hohenheim. It simulates the specific behavior of large-volume agricultural tires and is used in conjunction with multi-body models of tractors and other agricultural machines. Special focus is placed on driving dynamics and comfort. Currently the HTM is being expanded for implementation on soft soils. Therefor the soil's shear response using Bevameter tests and the relationship traction-wheel slip using a single wheel tester are investigated. In field tests, the effect of shear rate on soil mechanical parameters was examined. The shear device of the Bevameter was used to conduct experiments in a soil bin with silty loam at eight shear rates and five vertical loads. The Mohr-Coulomb failure criterion was calculated and the measured values were fitted to the Wong-Preston and the Janosi-Hanamoto approaches. The shear stress-shear displacement curves show two different behaviors with respect to shear rate. At high shear rates, the shear stress reaches a peak and then drops to a residual value, which is typical for cohesive soils. At low shear rates, the trend of the curves is exponential, which is typical for granular soils. The cohesion and angle of internal friction values are comparable to those from literature. The angle of internal friction has no correlation with shear rate while the cohesion shows a low correlation. Traction-wheel slip curves for the tractor tire 480/70 R24 with two tire loads (17 and 22 kN) and at 2 km∙h-1 were measured under identical conditions as the shear experiments. For the higher tire load, there is a tendency toward a larger tractive force. The curves of both wheel loads have equal gross traction coefficients. For the prediction of the traction force, the parameters obtained in the shear tests and the method of Wong and Preston-Thomas are used.","PeriodicalId":447600,"journal":{"name":"Proceedings of the 11th Asia-Pacific Regional Conference of the ISTVS","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2022-10-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"114718495","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
High trafficability and robustness on terrain surfaces composed of granular substrates can be obtained through configurations of C-shaped legs. Recently, C-shaped configuration has been widely used in the locomotion mechanism design of the legged mobile robots on harsh grounds, especially for sandy terrains. In case of rotational gait, based on the stress-macro deformation relationship according to the Resistive Force Theory (RFT) in terradynamics, an interaction model between a C-shaped leg and the sandy terrain is established in this paper. Considering the influence of velocity field of C- leg particle systems on Fourier linear coefficient in fitting precondition, the inversion characters of mechanical parameters through integral derivation and linearized expression of the model are established. Then, the experimental data samples are employed to identify the mechanical parameters of the sandy terrain, followed by checking its validity through setting a limit for the tolerance between predicted results and experimental data. Furthermore, mechanical behaviors under swing gaits are analyzed, for which some basic dynamic control strategies are suggested in this study. In this work, the outputs of driving torque within the range of a feasible region experienced at the joint are explored. It is concluded that the mechanical properties dominated by the sandy terrain and leg geometry can be revealed by the identified parameters, some driving outputs can be evaluated through interaction models in terradynamics.
{"title":"Interaction Modeling and Dynamic Control Strategy for C-Shaped Leg with Sandy Terrain in Terradynamics","authors":"Chuanxiao Yang, Zhiyue Xin, Xiong Hu, Shibin Sun, Liang Ding, Dewei Tang","doi":"10.56884/kbpt8232","DOIUrl":"https://doi.org/10.56884/kbpt8232","url":null,"abstract":"High trafficability and robustness on terrain surfaces composed of granular substrates can be obtained through configurations of C-shaped legs. Recently, C-shaped configuration has been widely used in the locomotion mechanism design of the legged mobile robots on harsh grounds, especially for sandy terrains. In case of rotational gait, based on the stress-macro deformation relationship according to the Resistive Force Theory (RFT) in terradynamics, an interaction model between a C-shaped leg and the sandy terrain is established in this paper. Considering the influence of velocity field of C- leg particle systems on Fourier linear coefficient in fitting precondition, the inversion characters of mechanical parameters through integral derivation and linearized expression of the model are established. Then, the experimental data samples are employed to identify the mechanical parameters of the sandy terrain, followed by checking its validity through setting a limit for the tolerance between predicted results and experimental data. Furthermore, mechanical behaviors under swing gaits are analyzed, for which some basic dynamic control strategies are suggested in this study. In this work, the outputs of driving torque within the range of a feasible region experienced at the joint are explored. It is concluded that the mechanical properties dominated by the sandy terrain and leg geometry can be revealed by the identified parameters, some driving outputs can be evaluated through interaction models in terradynamics.","PeriodicalId":447600,"journal":{"name":"Proceedings of the 11th Asia-Pacific Regional Conference of the ISTVS","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2022-10-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"117304354","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Mars surface exploration has attracted significant attention of scientists for exploiting new resources and space. To perform explorations on Mars surface, various structures of planetary rovers have been proposed. The Mars surface contains loose granular materials and various sizes of rocks. Traditional wheeled, crawler and legged structures of Mars rovers are mainly designed to walk on granular materials terrain, which are incapable of adapting to rocky surfaces. To improve the adaptations for both granular and rocky surfaces, this paper introduces a quadruped legged robot inspired by the locomotion of desert animal lizard that can walk on granular and rocky surfaces. The main feature is that the structure of the proposed robot possesses bionic multi-toe foot and flexible active spine. To verify the robot locomotion, kinematics on foot, leg and spine of the quadruped robot are analyzed. Furthermore, robot motions are analytically predicted with respect to two types of gaits. Combining control framework for adapting to both granular and rocky surfaces, a prototype of Mars robot has been manufactured. Experimental tests demonstrated that the bionic robot can walk on granular surfaces, and can also climb on rocky surface using the multi-joint toe with claw. Therefore, this bionic quadruped robot can have higher adaptability for Mars surface environment.
{"title":"Bionic Quadruped Robot for Mars Surface Exploration","authors":"Long Qiao, Guangming Chen, L. Richter, A. Ji","doi":"10.56884/wfts1248","DOIUrl":"https://doi.org/10.56884/wfts1248","url":null,"abstract":"Mars surface exploration has attracted significant attention of scientists for exploiting new resources and space. To perform explorations on Mars surface, various structures of planetary rovers have been proposed. The Mars surface contains loose granular materials and various sizes of rocks. Traditional wheeled, crawler and legged structures of Mars rovers are mainly designed to walk on granular materials terrain, which are incapable of adapting to rocky surfaces. To improve the adaptations for both granular and rocky surfaces, this paper introduces a quadruped legged robot inspired by the locomotion of desert animal lizard that can walk on granular and rocky surfaces. The main feature is that the structure of the proposed robot possesses bionic multi-toe foot and flexible active spine. To verify the robot locomotion, kinematics on foot, leg and spine of the quadruped robot are analyzed. Furthermore, robot motions are analytically predicted with respect to two types of gaits. Combining control framework for adapting to both granular and rocky surfaces, a prototype of Mars robot has been manufactured. Experimental tests demonstrated that the bionic robot can walk on granular surfaces, and can also climb on rocky surface using the multi-joint toe with claw. Therefore, this bionic quadruped robot can have higher adaptability for Mars surface environment.","PeriodicalId":447600,"journal":{"name":"Proceedings of the 11th Asia-Pacific Regional Conference of the ISTVS","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2022-10-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"133811518","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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