In this paper, two new indices for wheel and vehicle mobility performance suitable for mobility performance optimization are proposed based on the wheel circumferential forces and the vehicle actual linear velocity. The indices are intended for on-the go assessment of mobility for autonomous real-time optimization of wheel power distribution. The wheel mobility performance (WMP) characterizes the mobility performance of a wheel in terms of its traction and velocity with regard to a potential but unachievable maximum. The index is extended to a vehicle with a given number of drive wheels, where the traction characteristics and theoretical velocities may be different at each wheel, as the vehicle mobility performance (VMP). The VMP index is demonstrated through a simulated comparison of multiple driveline configurations of a 4x4 vehicle on different terrains to the optimal value. The optimal mobility is computed through an objective function with the use of Lagrange Multipliers which determine the optimal distribution of vehicle forces and slippages which achieve optimal mobility.
{"title":"A Wheel and Vehicle Mobility Index Based on Traction and Velocity for Optimization of Mobility Performance","authors":"V. Vantsevich, D. Gorsich, M. Ghasemi, L. Moradi","doi":"10.56884/zofe8973","DOIUrl":"https://doi.org/10.56884/zofe8973","url":null,"abstract":"In this paper, two new indices for wheel and vehicle mobility performance suitable for mobility performance optimization are proposed based on the wheel circumferential forces and the vehicle actual linear velocity. The indices are intended for on-the go assessment of mobility for autonomous real-time optimization of wheel power distribution. The wheel mobility performance (WMP) characterizes the mobility performance of a wheel in terms of its traction and velocity with regard to a potential but unachievable maximum. The index is extended to a vehicle with a given number of drive wheels, where the traction characteristics and theoretical velocities may be different at each wheel, as the vehicle mobility performance (VMP). The VMP index is demonstrated through a simulated comparison of multiple driveline configurations of a 4x4 vehicle on different terrains to the optimal value. The optimal mobility is computed through an objective function with the use of Lagrange Multipliers which determine the optimal distribution of vehicle forces and slippages which achieve optimal mobility.","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":"121894800","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}
In planetary exploration, rovers are used to move across the surface to obtain high-resolution topographic elevation maps, as well as to conduct mining and rock sampling. However, because of the harsh planetary environment, surface exploration poses many technical challenges. In this study, we assume an unmanned exploration rover that is small enough to be carried on a Japanese launch vehicle, and its weight is limited by the payload capacity of the launch vehicle. It is also important that the rover is not prone to failure. The surface of Mars is covered with fine sand called regolith, and this sand can get between the mechanisms and cause them to fail. Therefore, a rover with lightweight and simple mechanisms is needed. In addition, Mars has a large slope, and there are not only rocky terrain but also uneven terrain such as depressions and craters. For smooth exploration, the rover must travel a safe and efficient path to avoid tipping over or getting stuck. However, wheel slippage on the regolith makes it difficult to follow the target path precisely and can result in getting stuck. If an active steering mechanism is omitted in order to configure a simple and lightweight traveling system, and if the path following is attempted to be performed by the difference in rotation speed between left and right traveling mechanisms such as wheels and crawlers when traveling on a curved path, the ground of the traveling system is forced to skid, which places a severe load on the traveling system. Therefore, this study proposes a lightweight, simple, and passive mechanism that reduces skidding and provides good path-following performance. The proposed mechanism uses a passive Ackermann mechanism without actuators, and the steering is performed by the difference in rotational speed between the left and right wheels. Since there is no actuator for steering, the mechanism is lightweight and simple. In order to suppress steering in unintended directions, a weak spring is added in the direction that returns the steering angle to a straight line. This paper describes the results of a prototype wheeled rover mechanism incorporating the proposed mechanism in the size assumed and confirming its ability to follow a target path by running experiments on soil simulating the surface of Mars. The experimental results show that the proposed mechanism has a higher ability to follow the target path than a rover without a steering mechanism. In addition, the rover's ability to follow the target path was improved by correcting the steering angle with respect to the rotational speeds of the left and right wheels.
{"title":"Study of Passive Steering Mechanism for Mars Surface Exploration Rovers","authors":"Asahi Oe, Shinitiro Nishida, Shintaro Nakatani","doi":"10.56884/rdkv9886","DOIUrl":"https://doi.org/10.56884/rdkv9886","url":null,"abstract":"In planetary exploration, rovers are used to move across the surface to obtain high-resolution topographic elevation maps, as well as to conduct mining and rock sampling. However, because of the harsh planetary environment, surface exploration poses many technical challenges. In this study, we assume an unmanned exploration rover that is small enough to be carried on a Japanese launch vehicle, and its weight is limited by the payload capacity of the launch vehicle. It is also important that the rover is not prone to failure. The surface of Mars is covered with fine sand called regolith, and this sand can get between the mechanisms and cause them to fail. Therefore, a rover with lightweight and simple mechanisms is needed. In addition, Mars has a large slope, and there are not only rocky terrain but also uneven terrain such as depressions and craters. For smooth exploration, the rover must travel a safe and efficient path to avoid tipping over or getting stuck. However, wheel slippage on the regolith makes it difficult to follow the target path precisely and can result in getting stuck. If an active steering mechanism is omitted in order to configure a simple and lightweight traveling system, and if the path following is attempted to be performed by the difference in rotation speed between left and right traveling mechanisms such as wheels and crawlers when traveling on a curved path, the ground of the traveling system is forced to skid, which places a severe load on the traveling system. Therefore, this study proposes a lightweight, simple, and passive mechanism that reduces skidding and provides good path-following performance. The proposed mechanism uses a passive Ackermann mechanism without actuators, and the steering is performed by the difference in rotational speed between the left and right wheels. Since there is no actuator for steering, the mechanism is lightweight and simple. In order to suppress steering in unintended directions, a weak spring is added in the direction that returns the steering angle to a straight line. This paper describes the results of a prototype wheeled rover mechanism incorporating the proposed mechanism in the size assumed and confirming its ability to follow a target path by running experiments on soil simulating the surface of Mars. The experimental results show that the proposed mechanism has a higher ability to follow the target path than a rover without a steering mechanism. In addition, the rover's ability to follow the target path was improved by correcting the steering angle with respect to the rotational speeds of the left and right wheels.","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":"130967935","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}
Ye Zhuang, Haojie Sun, Yingchun Qi, Weiguang Fan, Hui Ye
Vertical vibration of the terrain vehicle involves its comfort, maneuverability, and fatigue life of the key components. The type of road surface encountered by the vehicle is very complex and difficult to measure. Besides, the damper system has a strong non-linearity, which makes the design of the vehicle suspension controller difficult. Compared with the active suspension, the semiactive suspension has the advantages of low energy consumption and high safety, therefore this paper uses semi-active magneto-rheological damper and reinforcement learning technology, from the comfort point of view, to solve the suspension random optimal control problem. It is expected to improve the comfort of the terrain-vehicle with intelligent, low-power control method. This paper applies Gaussian Process (GP) technology to learn and model the nonlinear part of the terrain vehicle system, and then carries out the design of the reinforcement learning control strategy, establishes a linear control law with the suspension deflection, the sprung mass velocity, and the unsprung mass velocity as the feedback variables. The introduced reinforcement learning algorithm learns the appropriate feedback gain during the interaction process with the system, and then uses the learned feedback gain to carry out system simulation and experimental analysis. The paper compares the reinforcement learning algorithm with other classical semi-active control algorithms under the input of random, bump and sinusoidal pavement, and the analysis results show that the reinforcement learning algorithm introduced in the paper has excellent control effect in the full frequency band and can provide good comfort for terrain vehicles under the condition of low power consumption.
{"title":"Semi-Active Reinforcement Learning Suspension Control for the Off-Road Vehicles","authors":"Ye Zhuang, Haojie Sun, Yingchun Qi, Weiguang Fan, Hui Ye","doi":"10.56884/bcor8152","DOIUrl":"https://doi.org/10.56884/bcor8152","url":null,"abstract":"Vertical vibration of the terrain vehicle involves its comfort, maneuverability, and fatigue life of the key components. The type of road surface encountered by the vehicle is very complex and difficult to measure. Besides, the damper system has a strong non-linearity, which makes the design of the vehicle suspension controller difficult. Compared with the active suspension, the semiactive suspension has the advantages of low energy consumption and high safety, therefore this paper uses semi-active magneto-rheological damper and reinforcement learning technology, from the comfort point of view, to solve the suspension random optimal control problem. It is expected to improve the comfort of the terrain-vehicle with intelligent, low-power control method. This paper applies Gaussian Process (GP) technology to learn and model the nonlinear part of the terrain vehicle system, and then carries out the design of the reinforcement learning control strategy, establishes a linear control law with the suspension deflection, the sprung mass velocity, and the unsprung mass velocity as the feedback variables. The introduced reinforcement learning algorithm learns the appropriate feedback gain during the interaction process with the system, and then uses the learned feedback gain to carry out system simulation and experimental analysis. The paper compares the reinforcement learning algorithm with other classical semi-active control algorithms under the input of random, bump and sinusoidal pavement, and the analysis results show that the reinforcement learning algorithm introduced in the paper has excellent control effect in the full frequency band and can provide good comfort for terrain vehicles under the condition of low power consumption.","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":"130344297","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}
Hui Xi, Yanjing Li, Pengyu Sun, Weihua Li, Jianfeng Wang
Four wheeled differential mobile robots have been widely used in many fields. However, on the slippery surfaces (e.g., marble floor), the tire-terrain contact surfaces may induce phenomena of slipping especially when it turns, which brings big challenges for its teleoperation. Aiming at this difficulty, a time-domain passive controller (TDPC) is proposed in this study to compensate for the active energy generated by the environment termination induced by the tire-terrain interaction, and then a stable teleoperator is designed under the coordination of master robot's position and slave robot's velocity. Experiments with a commercial four wheeled mobile robots on the marble floor are conducted to validate the proposed approach.
{"title":"A Time Domain Passivity Controller for Teleoperation of Four Wheeled Differential Mobile Robot on Slippery Surface","authors":"Hui Xi, Yanjing Li, Pengyu Sun, Weihua Li, Jianfeng Wang","doi":"10.56884/bsme8486","DOIUrl":"https://doi.org/10.56884/bsme8486","url":null,"abstract":"Four wheeled differential mobile robots have been widely used in many fields. However, on the slippery surfaces (e.g., marble floor), the tire-terrain contact surfaces may induce phenomena of slipping especially when it turns, which brings big challenges for its teleoperation. Aiming at this difficulty, a time-domain passive controller (TDPC) is proposed in this study to compensate for the active energy generated by the environment termination induced by the tire-terrain interaction, and then a stable teleoperator is designed under the coordination of master robot's position and slave robot's velocity. Experiments with a commercial four wheeled mobile robots on the marble floor are conducted to validate the proposed approach.","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":"130503814","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}
Junlong Guo, Xingyang Zhang, Yunpeng Dong, Zhao Xue, Bo Huang
Scene information plays a crucial role in motion control, attitude perception, and path planning for wheeled planetary rovers (WPRs). Terrain recognition is the fundamental component of scene recognition. Due to the rich information, visual sensors are usually used in terrain classification. However, teleoperation delay prevents WPRs from using visual information efficiently. End-to-end learning method of deep learning (DL) that does not need complex image preprocessing was proposed to deal with this issue. This paper first built a terrain dataset (consists of loose sand, bedrock, small rock, large rock, and outcrop) using real Mars images to directly support You Only Look Once (YOLOv5) to test its performance on terrain classification. Because the capability of end-to-end training scheme is positively correlated with dataset, the performance of YOLOv5 can be significantly improved by exploiting orders of magnitude more data. The best combination of hyperparameters and models was achieved by slightly tuning YOLOv5, and data augmentation was also applied to optimize its accuracy. Furthermore, its performance was compared with two other end-to-end network architectures. Deep learning algorithms can be used in the future planetary exploration missions, such as WPRs autonomy improvement, traversability analysis, and avoiding getting trapped.
场景信息在轮式行星漫游者的运动控制、姿态感知和路径规划中起着至关重要的作用。地形识别是场景识别的基本组成部分。由于视觉传感器具有丰富的信息，因此通常用于地形分类。然而，远程操作的延迟影响了WPRs对视觉信息的有效利用。针对这一问题，提出了不需要对复杂图像进行预处理的深度学习(DL)端到端学习方法。本文首先利用真实火星图像构建地形数据集(由松散的沙子、基岩、小岩石、大岩石和露头组成)，直接支持You Only Look Once (YOLOv5)，测试其地形分类性能。由于端到端训练方案的能力与数据集呈正相关，因此YOLOv5可以通过利用数量级的数据来显著提高性能。通过对YOLOv5进行微调，实现了超参数和模型的最佳组合，并采用数据增强方法优化其精度。此外，将其性能与另外两种端到端网络体系结构进行了比较。深度学习算法可用于未来的行星探测任务，如wpr自主性改进、可遍历性分析、避免被困等。
{"title":"Terrain Classification Using Mars Raw Images Based on Deep Learning Algorithms with Application to Wheeled Planetary Rovers","authors":"Junlong Guo, Xingyang Zhang, Yunpeng Dong, Zhao Xue, Bo Huang","doi":"10.56884/wsdo4112","DOIUrl":"https://doi.org/10.56884/wsdo4112","url":null,"abstract":"Scene information plays a crucial role in motion control, attitude perception, and path planning for wheeled planetary rovers (WPRs). Terrain recognition is the fundamental component of scene recognition. Due to the rich information, visual sensors are usually used in terrain classification. However, teleoperation delay prevents WPRs from using visual information efficiently. End-to-end learning method of deep learning (DL) that does not need complex image preprocessing was proposed to deal with this issue. This paper first built a terrain dataset (consists of loose sand, bedrock, small rock, large rock, and outcrop) using real Mars images to directly support You Only Look Once (YOLOv5) to test its performance on terrain classification. Because the capability of end-to-end training scheme is positively correlated with dataset, the performance of YOLOv5 can be significantly improved by exploiting orders of magnitude more data. The best combination of hyperparameters and models was achieved by slightly tuning YOLOv5, and data augmentation was also applied to optimize its accuracy. Furthermore, its performance was compared with two other end-to-end network architectures. Deep learning algorithms can be used in the future planetary exploration missions, such as WPRs autonomy improvement, traversability analysis, and avoiding getting trapped.","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":"134161711","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}
Remotely piloted robots have been expected for disaster operations to prevent secondary disasters to rescuers. The robots are required to have a high performance to overcome obstacles such as debris and bumps. Tracked robots with flipper arms on the front, back, left, and right sides can improve their ability to overcome bumps by changing the flipper angles, and are thus expected to be used as rescue robots. However, the six degrees of freedom of the left and right crawlers and four flipper arms require a high level of skill to maneuver the robot. Therefore, a semi-autonomous control system that automatically controls the flipper arms according to the terrain is expected. In this study, we proposed a method to determine the front and rear flipper angles in step-climbing using reinforcement learning with Double Deep Q Network. The input data were the step height, distance to the step, and current front and rear flipper angles. The outputs were amounts of front and rear flipper angle variations. The behavior of the robot and rewards were calculated using a quasi-static model that considers the slips between the step, floor, and crawler. Positive rewards were given for successful step stepping over steps and negative rewards for unsuccessful steps. Furthermore, the flipper motions at which slippage decreased were obtained by subtracting the sum of the squared values of the slippage rates from the rewards. As the results, it was confirmed that the robot slips less when the body is lifted by the rear flipper than when it runs over along the step shape.
{"title":"Acquisition of Flipper Motion in Step-Climbing of Tracked Robot Using Reinforcement Learning","authors":"Ryosuke Eto, J. Yamakawa","doi":"10.56884/sgwj1011","DOIUrl":"https://doi.org/10.56884/sgwj1011","url":null,"abstract":"Remotely piloted robots have been expected for disaster operations to prevent secondary disasters to rescuers. The robots are required to have a high performance to overcome obstacles such as debris and bumps. Tracked robots with flipper arms on the front, back, left, and right sides can improve their ability to overcome bumps by changing the flipper angles, and are thus expected to be used as rescue robots. However, the six degrees of freedom of the left and right crawlers and four flipper arms require a high level of skill to maneuver the robot. Therefore, a semi-autonomous control system that automatically controls the flipper arms according to the terrain is expected. In this study, we proposed a method to determine the front and rear flipper angles in step-climbing using reinforcement learning with Double Deep Q Network. The input data were the step height, distance to the step, and current front and rear flipper angles. The outputs were amounts of front and rear flipper angle variations. The behavior of the robot and rewards were calculated using a quasi-static model that considers the slips between the step, floor, and crawler. Positive rewards were given for successful step stepping over steps and negative rewards for unsuccessful steps. Furthermore, the flipper motions at which slippage decreased were obtained by subtracting the sum of the squared values of the slippage rates from the rewards. As the results, it was confirmed that the robot slips less when the body is lifted by the rear flipper than when it runs over along the step shape.","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":"132124902","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}
Guozhong Zhang, Hongchang Wang, Jun Du, Kaiquan Ding, Wanru Liu, Nanrui Tang, Yong Zhou
There is a large number of paddy fields in South China. During rice sowing and transplanting, agronomy requires the topsoil to be soft, viscous, muddy, mixed with water and disturbed-saturated mud, after soaking, tilling and rotary harrowing. At this time, the soil has a high fluidity, high adhesion and low shear strength. Thus, it would be productive to research the contact relationship between the soil contacting parts and the soil surface, so as to improve the operational efficiency of the tillage and planting machinery of paddy field in this soil condition. For this purpose, the disturbed-saturated soil formation process is described, the coupling mechanism between soil-engaging components and such soil conditions is clarified and the current state and prospects of research on soil-tool interactions under paddy field conditions is analyzed. This paper is expected to serve as a useful reference for future work in studying the surface characteristic parameters of soil contacting parts; the coupling correlation mechanism of "contact-rheologyresistance" among the structural shape, motional parameters and the disturbed paddy field soil, creating favorable conditions at the soil-tool contact interface for drag force reduction in the paddy field soil, the design and the optimization of paddy field equipment in South China, and the research on the technology of reducing viscosity and drag force of paddy field machinery.
{"title":"Prominent problems and thoughts of \"paddy soil-terrain machine system\" based on disturbed saturated paddy soil conditions in South China","authors":"Guozhong Zhang, Hongchang Wang, Jun Du, Kaiquan Ding, Wanru Liu, Nanrui Tang, Yong Zhou","doi":"10.56884/chsd4959","DOIUrl":"https://doi.org/10.56884/chsd4959","url":null,"abstract":"There is a large number of paddy fields in South China. During rice sowing and transplanting, agronomy requires the topsoil to be soft, viscous, muddy, mixed with water and disturbed-saturated mud, after soaking, tilling and rotary harrowing. At this time, the soil has a high fluidity, high adhesion and low shear strength. Thus, it would be productive to research the contact relationship between the soil contacting parts and the soil surface, so as to improve the operational efficiency of the tillage and planting machinery of paddy field in this soil condition. For this purpose, the disturbed-saturated soil formation process is described, the coupling mechanism between soil-engaging components and such soil conditions is clarified and the current state and prospects of research on soil-tool interactions under paddy field conditions is analyzed. This paper is expected to serve as a useful reference for future work in studying the surface characteristic parameters of soil contacting parts; the coupling correlation mechanism of \"contact-rheologyresistance\" among the structural shape, motional parameters and the disturbed paddy field soil, creating favorable conditions at the soil-tool contact interface for drag force reduction in the paddy field soil, the design and the optimization of paddy field equipment in South China, and the research on the technology of reducing viscosity and drag force of paddy field machinery.","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":"130270608","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}
Aiming at the possible wheel sinkage, difficulty in climbing and underpinning of Mars rover with traditional passive suspension due to the complex terrain of Mars surface, the characteristics of the inchworm motion are imitated, and a creeping Mars rover is designed, include the design of sinkage and extrication, slope-climbing, anti-underpinning, and wheel-lifting. The key parameters of the mobile system of creeping rover are identified and the key parameter values of different rover lift heights and the displacement value of a creeping cycle are calculated. and the results show that the creeping rover can solve the above problems encountered by the passive suspension rover. Ground tests and flight tests have been carried out on the designed creeping rover, and the ground tests have verified the ability of wheel sinkage and extrication, obstacle-overcoming, and slope-climbing. As an example of the application of the creeping rover, the “Zhurong” Mars rover has undergone flight tests, and its successful operation on the surface of Mars shows that the design measures of the creeping are effective.
{"title":"Design and Verification of a Creeping Mars Rover","authors":"Wangjun Zhang, Yang Jia, Zhu Tao","doi":"10.56884/bjjs7767","DOIUrl":"https://doi.org/10.56884/bjjs7767","url":null,"abstract":"Aiming at the possible wheel sinkage, difficulty in climbing and underpinning of Mars rover with traditional passive suspension due to the complex terrain of Mars surface, the characteristics of the inchworm motion are imitated, and a creeping Mars rover is designed, include the design of sinkage and extrication, slope-climbing, anti-underpinning, and wheel-lifting. The key parameters of the mobile system of creeping rover are identified and the key parameter values of different rover lift heights and the displacement value of a creeping cycle are calculated. and the results show that the creeping rover can solve the above problems encountered by the passive suspension rover. Ground tests and flight tests have been carried out on the designed creeping rover, and the ground tests have verified the ability of wheel sinkage and extrication, obstacle-overcoming, and slope-climbing. As an example of the application of the creeping rover, the “Zhurong” Mars rover has undergone flight tests, and its successful operation on the surface of Mars shows that the design measures of the creeping are effective.","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":"122878657","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}
G. Reina, Rocco Galati, A. Grazioso, Angelo Ugenti, G. Mantriota
In the context of autonomous off-road mobility, tracked robots feature larger contact areas compared to equivalent wheeled vehicles, which turn into improved traction especially on soft terrains. This paper discusses a novel tracked robot, named Polibot, that is outfitted with passive articulated suspensions. The multibody model is developed within the MSC Adams environment leveraging on the Adams Tracked Vehicle (ATV) Toolkit. The different subsystems composing the vehicle assembly are outlined, with specific attention to the modeling strategies of the swing arms constituting the suspension system, as well as the characterization of the track belt and inertial properties. Efforts in validating the multibody twin against the real prototype are also presented, showing a good agreement in experiments performed on asphalt.
{"title":"Introducing Polibot: A High Mobility Tracked Robot with Innovative Passive Suspensions","authors":"G. Reina, Rocco Galati, A. Grazioso, Angelo Ugenti, G. Mantriota","doi":"10.56884/qyuy9071","DOIUrl":"https://doi.org/10.56884/qyuy9071","url":null,"abstract":"In the context of autonomous off-road mobility, tracked robots feature larger contact areas compared to equivalent wheeled vehicles, which turn into improved traction especially on soft terrains. This paper discusses a novel tracked robot, named Polibot, that is outfitted with passive articulated suspensions. The multibody model is developed within the MSC Adams environment leveraging on the Adams Tracked Vehicle (ATV) Toolkit. The different subsystems composing the vehicle assembly are outlined, with specific attention to the modeling strategies of the swing arms constituting the suspension system, as well as the characterization of the track belt and inertial properties. Efforts in validating the multibody twin against the real prototype are also presented, showing a good agreement in experiments performed on asphalt.","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":"114594634","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 Bekker-Wong soil-wheel interaction model has been widely adopted in the terramechanics community. This approach requires data measured with a Bevameter. The Bevameter test includes a pressure-sinkage test and a shear strength test. Although the original intention of the Bevameter method is to closely replicate the interaction between the wheel/track and the soil, tests are often done at lower vertical loads with smaller contact areas to keep tests within practical experimental limits. The traditional Bevameter shear strength test, which uses a rotational shear ring with grousers, tends to overpredict the drawbar pull of vehicles by 30 to 40% [(Chang and Baker, 1973, Shoop, 1993)]. Translational shear arguably more closely resembles the shear mechanism that occurs between a wheel/track and the soil. The literature indicates that terramechanics investigations are significantly influenced by soil condition and preparation. This study investigates (a) the influence of soil preparation on the pressure-sinkage and shear-displacement relationship of sandy soil, (b) the influence of the shearing mechanism on shear strength, and (c) the influence of shear contact area on shear strength. Experimental results indicate that soil preparation has a substantial influence on the pressure-sinkage relationship. The shearing mechanism was investigated by comparing traditional rotational shear with translational shear. The findings indicate that the shearing mechanism may explain the overprediction of shear strength typical of rotational shear tests. The shear contact area also exhibits a significant influence on the measured shear strength. Further investigation into the shear mechanism and size and shape of the shear contact area is recommended.
{"title":"Factors Affecting Bevameter Soil Characterization","authors":"S. Els, H. Hamersma, R. Kruger","doi":"10.56884/ikrl4697","DOIUrl":"https://doi.org/10.56884/ikrl4697","url":null,"abstract":"The Bekker-Wong soil-wheel interaction model has been widely adopted in the terramechanics community. This approach requires data measured with a Bevameter. The Bevameter test includes a pressure-sinkage test and a shear strength test. Although the original intention of the Bevameter method is to closely replicate the interaction between the wheel/track and the soil, tests are often done at lower vertical loads with smaller contact areas to keep tests within practical experimental limits. The traditional Bevameter shear strength test, which uses a rotational shear ring with grousers, tends to overpredict the drawbar pull of vehicles by 30 to 40% [(Chang and Baker, 1973, Shoop, 1993)]. Translational shear arguably more closely resembles the shear mechanism that occurs between a wheel/track and the soil. The literature indicates that terramechanics investigations are significantly influenced by soil condition and preparation. This study investigates (a) the influence of soil preparation on the pressure-sinkage and shear-displacement relationship of sandy soil, (b) the influence of the shearing mechanism on shear strength, and (c) the influence of shear contact area on shear strength. Experimental results indicate that soil preparation has a substantial influence on the pressure-sinkage relationship. The shearing mechanism was investigated by comparing traditional rotational shear with translational shear. The findings indicate that the shearing mechanism may explain the overprediction of shear strength typical of rotational shear tests. The shear contact area also exhibits a significant influence on the measured shear strength. Further investigation into the shear mechanism and size and shape of the shear contact area is recommended.","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":"113977388","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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