The Experts below are selected from a list of 3876 Experts worldwide ranked by ideXlab platform
Matthew Spenko - One of the best experts on this subject based on the ideXlab platform.
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A pressure-Sinkage model for small-diameter wheels on compactive, deformable terrain
Journal of Terramechanics, 2013Co-Authors: Gareth Meirion-griffith, Matthew SpenkoAbstract:Abstract Traditional terramechanics theorems utilize pressure-Sinkage models based on the assumption that the contact area between a tire and soil can be approximated as a flat plate. Examples include work by Bernstein–Goriatchkin, Bekker, Reece, and Ishigami. Recently, the authors have demonstrated that (1) this assumption does not hold for wheels with a diameter less than approximately 50 cm and (2) an improved diameter-dependent pressure-Sinkage model can yield more accurate results. Further improvements to the pressure-Sinkage model for small diameter wheels are presented here that account for both wheel width and diameter on compactive soils. Results from 125 pressure-Sinkage tests using 35 wheel geometries on a clay/silt mix are presented. X-ray images of sub-surface soil deformation are used to visually validate the model.
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Comprehensive pressure-Sinkage model for small-wheeled unmanned ground vehicles on dilative, deformable terrain
2012 IEEE International Conference on Robotics and Automation, 2012Co-Authors: Gareth Meirion-griffith, Matthew SpenkoAbstract:This paper details a novel pressure-Sinkage model for small-diameter, rigid wheels on dilative soils. Pressure-Sinkage models are fundamental to the prediction of UGV mobility on deformable terrains. The proposed model builds on previous work in which the flat-plate pressure-Sinkage assumption of classical terramechanics was shown to yield diminished accuracy for UGVs with wheels less than 50 cm in diameter. It has been shown that classical pressure-Sinkage models can be modified by a diameter dependent term, yielding greatly increased accuracy. Here, an investigation into the effect of wheel width on the diameter-dependent model is detailed. Results from over 250 pressure-Sinkage tests on three soils using 85 wheel geometries are summarized. The results of this investigation are used to create a comprehensive pressure-Sinkage model for dilative soils that includes wheel width and diameter parameters. The physics of the model are visually validated with X-ray images of sub-surface soil deformation during the wheel indentation process. A comparison between the dilative soil pressure-Sinkage model and a previously obtained model for compactive soils is also presented. The pressure-Sinkage model presented here can be used to improve the accuracy of the terramechanics framework and UGV mobility predictions.
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ICRA - Comprehensive pressure-Sinkage model for small-wheeled unmanned ground vehicles on dilative, deformable terrain
2012 IEEE International Conference on Robotics and Automation, 2012Co-Authors: Gareth Meirion-griffith, Matthew SpenkoAbstract:This paper details a novel pressure-Sinkage model for small-diameter, rigid wheels on dilative soils. Pressure-Sinkage models are fundamental to the prediction of UGV mobility on deformable terrains. The proposed model builds on previous work in which the flat-plate pressure-Sinkage assumption of classical terramechanics was shown to yield diminished accuracy for UGVs with wheels less than 50 cm in diameter. It has been shown that classical pressure-Sinkage models can be modified by a diameter dependent term, yielding greatly increased accuracy. Here, an investigation into the effect of wheel width on the diameter-dependent model is detailed. Results from over 250 pressure-Sinkage tests on three soils using 85 wheel geometries are summarized. The results of this investigation are used to create a comprehensive pressure-Sinkage model for dilative soils that includes wheel width and diameter parameters. The physics of the model are visually validated with X-ray images of sub-surface soil deformation during the wheel indentation process. A comparison between the dilative soil pressure-Sinkage model and a previously obtained model for compactive soils is also presented. The pressure-Sinkage model presented here can be used to improve the accuracy of the terramechanics framework and UGV mobility predictions.
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a modified pressure Sinkage model for small rigid wheels on deformable terrains
Journal of Terramechanics, 2011Co-Authors: Gareth Meiriongriffith, Matthew SpenkoAbstract:Abstract Bekker’s semi-empirically derived equations allow the designers of off-road vehicles to understand and predict vehicle mobility performance over deformable terrains. However, there are several underlying assumptions that prevent Bekker theory from being successfully applied to small vehicles. Specifically, Bekker’s Sinkage and compaction resistance equations are inaccurate for vehicles with wheel diameters less than approximately 50 cm and normal loading less than approximately 45 N. This paper presents a modified pressure–Sinkage model that is shown to reduce Sinkage and compaction resistance model errors significantly. The modification is validated with results from 160 experiments using five wheel diameters and three soil types.
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TOWARD ESTABLISHING A COMPREHENSIVE PRESSURE-Sinkage MODEL FOR SMALL DIAMETER WHEELS ON DEFORMABLE TERRAINS
2011Co-Authors: Gareth Meirion-griffith, Matthew SpenkoAbstract:Traditional terramechanics theorems utilise pressure-Sinkage models based on the assumption that the contact area between a tyre and soil can be approximated as a flat plate. Examples include work by Bekker, Reece, and Ishigami. Recently, the authors have demonstrated that 1) this approximation does not hold for wheels with a diameter less than approximately 50 cm and 2) an improved diameter-dependent pressure-Sinkage model can yield more accurate results. In this paper, further improvements to the pressure-Sinkage model for small diameter wheels are presented. First the diameter-dependent pressure-Sinkage model is augmented with a geometric relationship to account for the normal stress distribution at the wheel-soil interface. Second, the effect of wheel width is investigated. The models are verified with field tests using a man-portable unmanned ground vehicle on wet sand and laboratory experiments on dilative (dry quartz sand) and compactive (kaolin-clay/silt mix) soils. Results indicate that the diameter-dependent pressure-Sinkage model outperforms previous models in predicting drawbar pull as a function of slip and that the effect of wheel width on the pressure-Sinkage model is highly dependent on the soil type.
Gareth Meirion-griffith - One of the best experts on this subject based on the ideXlab platform.
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A pressure-Sinkage model for small-diameter wheels on compactive, deformable terrain
Journal of Terramechanics, 2013Co-Authors: Gareth Meirion-griffith, Matthew SpenkoAbstract:Abstract Traditional terramechanics theorems utilize pressure-Sinkage models based on the assumption that the contact area between a tire and soil can be approximated as a flat plate. Examples include work by Bernstein–Goriatchkin, Bekker, Reece, and Ishigami. Recently, the authors have demonstrated that (1) this assumption does not hold for wheels with a diameter less than approximately 50 cm and (2) an improved diameter-dependent pressure-Sinkage model can yield more accurate results. Further improvements to the pressure-Sinkage model for small diameter wheels are presented here that account for both wheel width and diameter on compactive soils. Results from 125 pressure-Sinkage tests using 35 wheel geometries on a clay/silt mix are presented. X-ray images of sub-surface soil deformation are used to visually validate the model.
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Comprehensive pressure-Sinkage model for small-wheeled unmanned ground vehicles on dilative, deformable terrain
2012 IEEE International Conference on Robotics and Automation, 2012Co-Authors: Gareth Meirion-griffith, Matthew SpenkoAbstract:This paper details a novel pressure-Sinkage model for small-diameter, rigid wheels on dilative soils. Pressure-Sinkage models are fundamental to the prediction of UGV mobility on deformable terrains. The proposed model builds on previous work in which the flat-plate pressure-Sinkage assumption of classical terramechanics was shown to yield diminished accuracy for UGVs with wheels less than 50 cm in diameter. It has been shown that classical pressure-Sinkage models can be modified by a diameter dependent term, yielding greatly increased accuracy. Here, an investigation into the effect of wheel width on the diameter-dependent model is detailed. Results from over 250 pressure-Sinkage tests on three soils using 85 wheel geometries are summarized. The results of this investigation are used to create a comprehensive pressure-Sinkage model for dilative soils that includes wheel width and diameter parameters. The physics of the model are visually validated with X-ray images of sub-surface soil deformation during the wheel indentation process. A comparison between the dilative soil pressure-Sinkage model and a previously obtained model for compactive soils is also presented. The pressure-Sinkage model presented here can be used to improve the accuracy of the terramechanics framework and UGV mobility predictions.
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ICRA - Comprehensive pressure-Sinkage model for small-wheeled unmanned ground vehicles on dilative, deformable terrain
2012 IEEE International Conference on Robotics and Automation, 2012Co-Authors: Gareth Meirion-griffith, Matthew SpenkoAbstract:This paper details a novel pressure-Sinkage model for small-diameter, rigid wheels on dilative soils. Pressure-Sinkage models are fundamental to the prediction of UGV mobility on deformable terrains. The proposed model builds on previous work in which the flat-plate pressure-Sinkage assumption of classical terramechanics was shown to yield diminished accuracy for UGVs with wheels less than 50 cm in diameter. It has been shown that classical pressure-Sinkage models can be modified by a diameter dependent term, yielding greatly increased accuracy. Here, an investigation into the effect of wheel width on the diameter-dependent model is detailed. Results from over 250 pressure-Sinkage tests on three soils using 85 wheel geometries are summarized. The results of this investigation are used to create a comprehensive pressure-Sinkage model for dilative soils that includes wheel width and diameter parameters. The physics of the model are visually validated with X-ray images of sub-surface soil deformation during the wheel indentation process. A comparison between the dilative soil pressure-Sinkage model and a previously obtained model for compactive soils is also presented. The pressure-Sinkage model presented here can be used to improve the accuracy of the terramechanics framework and UGV mobility predictions.
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TOWARD ESTABLISHING A COMPREHENSIVE PRESSURE-Sinkage MODEL FOR SMALL DIAMETER WHEELS ON DEFORMABLE TERRAINS
2011Co-Authors: Gareth Meirion-griffith, Matthew SpenkoAbstract:Traditional terramechanics theorems utilise pressure-Sinkage models based on the assumption that the contact area between a tyre and soil can be approximated as a flat plate. Examples include work by Bekker, Reece, and Ishigami. Recently, the authors have demonstrated that 1) this approximation does not hold for wheels with a diameter less than approximately 50 cm and 2) an improved diameter-dependent pressure-Sinkage model can yield more accurate results. In this paper, further improvements to the pressure-Sinkage model for small diameter wheels are presented. First the diameter-dependent pressure-Sinkage model is augmented with a geometric relationship to account for the normal stress distribution at the wheel-soil interface. Second, the effect of wheel width is investigated. The models are verified with field tests using a man-portable unmanned ground vehicle on wet sand and laboratory experiments on dilative (dry quartz sand) and compactive (kaolin-clay/silt mix) soils. Results indicate that the diameter-dependent pressure-Sinkage model outperforms previous models in predicting drawbar pull as a function of slip and that the effect of wheel width on the pressure-Sinkage model is highly dependent on the soil type.
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A modified pressure–Sinkage model for small, rigid wheels on deformable terrains
Journal of Terramechanics, 2011Co-Authors: Gareth Meirion-griffith, Matthew SpenkoAbstract:Abstract Bekker’s semi-empirically derived equations allow the designers of off-road vehicles to understand and predict vehicle mobility performance over deformable terrains. However, there are several underlying assumptions that prevent Bekker theory from being successfully applied to small vehicles. Specifically, Bekker’s Sinkage and compaction resistance equations are inaccurate for vehicles with wheel diameters less than approximately 50 cm and normal loading less than approximately 45 N. This paper presents a modified pressure–Sinkage model that is shown to reduce Sinkage and compaction resistance model errors significantly. The modification is validated with results from 160 experiments using five wheel diameters and three soil types.
Liang Ding - One of the best experts on this subject based on the ideXlab platform.
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Sinkage definition and visual detection for planetary rovers wheels on rough terrain based on wheel soil interaction boundary
Robotics and Autonomous Systems, 2017Co-Authors: Haibo Gao, Liang Ding, Baofeng Yuan, Guangjun Liu, Zongquan DengAbstract:Abstract Wheel Sinkage detection is of tremendous significance for planetary rover mobility optimization control and prevention of serious wheel sinking. Wheel Sinkage is regarded as the distance between the lowest point of the wheel in the soil and the horizontal flat terrain on relative research. For rovers moving on rough terrains, the above definition is not reasonable because the horizontal flat terrain cannot be found. New wheel Sinkage definition and detection method are proposed, based on vision. The Sinkage definition rationality is analyzed for various terrain conditions. The discrete mathematical wheel Sinkage calculation model, for which the input is acquired through a visual method, is built. Saturation of wheel–soil interaction image is adjusted by a dynamic piecewise nonlinear adjustment method The image is processed into a binary image based on HSI (Hue, Saturation, Intensity) color space. The wheel–soil boundary is extracted from the corrected wheel region outline according to its morphological features. The wheel Sinkage and equivalent terrain interface angles are calculated through the discrete mathematical wheel Sinkage calculation model. Sinkage definition rationality and detection method applicability are experimentally validated in the four typical terrain conditions (flat, bulgy, sunken, and uneven terrains). Particularly, the experimental results prove the Sinkage detection method has high accuracy for flat terrain, for which, the deviation of the Sinkage modulus is less than 2% of the wheel radius. The Sinkage detection method is proved to have fairly reasonable adaptability to complex illumination conditions, based on the experimental results for different illumination conditions.
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Sinkage definition and visual detection for planetary rovers wheels on rough terrain based on wheel–soil interaction boundary
Robotics and Autonomous Systems, 2017Co-Authors: Haibo Gao, Liang Ding, Baofeng Yuan, Li Nan, Li Ningxi, Guangjun Liu, Zongquan DengAbstract:Abstract Wheel Sinkage detection is of tremendous significance for planetary rover mobility optimization control and prevention of serious wheel sinking. Wheel Sinkage is regarded as the distance between the lowest point of the wheel in the soil and the horizontal flat terrain on relative research. For rovers moving on rough terrains, the above definition is not reasonable because the horizontal flat terrain cannot be found. New wheel Sinkage definition and detection method are proposed, based on vision. The Sinkage definition rationality is analyzed for various terrain conditions. The discrete mathematical wheel Sinkage calculation model, for which the input is acquired through a visual method, is built. Saturation of wheel–soil interaction image is adjusted by a dynamic piecewise nonlinear adjustment method The image is processed into a binary image based on HSI (Hue, Saturation, Intensity) color space. The wheel–soil boundary is extracted from the corrected wheel region outline according to its morphological features. The wheel Sinkage and equivalent terrain interface angles are calculated through the discrete mathematical wheel Sinkage calculation model. Sinkage definition rationality and detection method applicability are experimentally validated in the four typical terrain conditions (flat, bulgy, sunken, and uneven terrains). Particularly, the experimental results prove the Sinkage detection method has high accuracy for flat terrain, for which, the deviation of the Sinkage modulus is less than 2% of the wheel radius. The Sinkage detection method is proved to have fairly reasonable adaptability to complex illumination conditions, based on the experimental results for different illumination conditions.
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Terramechanics-based modeling of Sinkage and moment for in-situ steering wheels of mobile robots on deformable terrain
Mechanism and Machine Theory, 2017Co-Authors: Liang Ding, Haibo Gao, Zongquan Deng, Li Ningxi, Huaiguang Yang, Junlong Guo, Li NanAbstract:Abstract The success of NASA's Mars missions has generated a renewed interest in planetary exploration, along with a need for better mobility of wheeled mobile robots (WMRs)—steering performance, in particular, has not yet reached an acceptable benchmark in high-precision models. This study focuses on the steering mechanics of WMRs, as it can enrich the terramechanics of planetary rovers. An improved Sinkage model based on the variable Sinkage exponent is proposed, and the Sinkage exponent is derived as a function of steering angle. Furthermore, a high-precision steering moment model is proposed based on the steering-Sinkage model, which considers the interaction area and the lug effect. The model can fit the results obtained by all of the experimental wheels, based on soil parameter identification. Most of the max relative errors (MREs) for the Sinkage are within 5%, and the coefficients of determination are more than 0.97. The MREs of moment increase with increasing vertical load but remain within 10%. This technique can also be applied to other WMRs with rigid wheels steering on deformable terrain.
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Longitudinal skid model for wheels of planetary rovers based on improved wheel Sinkage considering soil bulldozing effect
Journal of Terramechanics, 2017Co-Authors: Junlong Guo, Liang Ding, Haibo Gao, Zongquan Deng, Tianyou Guo, Zhen LiuAbstract:Abstract To successfully deploy a wheeled mobile robot on deformable rough terrains, the wheel-terrain interaction mechanics should be considered. Skid terramechanics is an essential part of the wheel terramechanics and has been studied by the authors based on the wheel Sinkage obtained using a linear displacement sensor that does not consider soil bulldozing effect. The Sinkage measured by a newly developed wheel via detecting the entrance angle is about 2 times of that measured by the linear displacement sensor. On the basis of the wheel Sinkage that takes the soil bulldozing effect into account, a linear function is proposed to the Sinkage exponent. Soil flow in the rear region of wheel-soil interface is considered in the calculation of soil shear displacement, and its average velocity is assumed to be equal to the tangential velocity component of the transition point of shear stress. To compute the normal stress in the rear region directly, the connection of the entrance and leaving points is supposed as the reference of wheel Sinkage. The wheel performance can be accurately estimated using the proposed model by comparing the simulation results against the experimental data obtained using two wheels and on two types of sands.
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improved explicit form equations for estimating dynamic wheel Sinkage and compaction resistance on deformable terrain
Mechanism and Machine Theory, 2015Co-Authors: Liang DingAbstract:Abstract The contact mechanics for a wheel and deformable terrain are complicated owing to the rigid–flexible coupling characteristics. This paper presents explicit-form analytical equations to estimate the wheel Sinkage and compaction resistance of autonomous robots that require high-accuracy terramechanics models. The limitations of Bekker's equations were analyzed both theoretically and through experiments on slip/skid Sinkages. The normal and shear stress distribution equations of the Wong–Reece model were improved through the use of a variable Sinkage exponent to reflect the dynamic Sinkage of robot wheels moving on deformable terrain. The improved integral-form equations were simplified to derive closed-form analytical equations for estimating the normal force, drawbar pull, and driving resistance moment; these were then used to derive explicit analytical equations to estimate the wheel Sinkage and compaction resistance as functions of the vertical load, terrain parameters, wheel parameters, and Sinkage exponent varying with the slip ratio. The experimental results for the contact mechanics of six different types of wheels and deformable terrain were used to verify the accuracy of the model.
Zongquan Deng - One of the best experts on this subject based on the ideXlab platform.
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Sinkage definition and visual detection for planetary rovers wheels on rough terrain based on wheel soil interaction boundary
Robotics and Autonomous Systems, 2017Co-Authors: Haibo Gao, Liang Ding, Baofeng Yuan, Guangjun Liu, Zongquan DengAbstract:Abstract Wheel Sinkage detection is of tremendous significance for planetary rover mobility optimization control and prevention of serious wheel sinking. Wheel Sinkage is regarded as the distance between the lowest point of the wheel in the soil and the horizontal flat terrain on relative research. For rovers moving on rough terrains, the above definition is not reasonable because the horizontal flat terrain cannot be found. New wheel Sinkage definition and detection method are proposed, based on vision. The Sinkage definition rationality is analyzed for various terrain conditions. The discrete mathematical wheel Sinkage calculation model, for which the input is acquired through a visual method, is built. Saturation of wheel–soil interaction image is adjusted by a dynamic piecewise nonlinear adjustment method The image is processed into a binary image based on HSI (Hue, Saturation, Intensity) color space. The wheel–soil boundary is extracted from the corrected wheel region outline according to its morphological features. The wheel Sinkage and equivalent terrain interface angles are calculated through the discrete mathematical wheel Sinkage calculation model. Sinkage definition rationality and detection method applicability are experimentally validated in the four typical terrain conditions (flat, bulgy, sunken, and uneven terrains). Particularly, the experimental results prove the Sinkage detection method has high accuracy for flat terrain, for which, the deviation of the Sinkage modulus is less than 2% of the wheel radius. The Sinkage detection method is proved to have fairly reasonable adaptability to complex illumination conditions, based on the experimental results for different illumination conditions.
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Sinkage definition and visual detection for planetary rovers wheels on rough terrain based on wheel–soil interaction boundary
Robotics and Autonomous Systems, 2017Co-Authors: Haibo Gao, Liang Ding, Baofeng Yuan, Li Nan, Li Ningxi, Guangjun Liu, Zongquan DengAbstract:Abstract Wheel Sinkage detection is of tremendous significance for planetary rover mobility optimization control and prevention of serious wheel sinking. Wheel Sinkage is regarded as the distance between the lowest point of the wheel in the soil and the horizontal flat terrain on relative research. For rovers moving on rough terrains, the above definition is not reasonable because the horizontal flat terrain cannot be found. New wheel Sinkage definition and detection method are proposed, based on vision. The Sinkage definition rationality is analyzed for various terrain conditions. The discrete mathematical wheel Sinkage calculation model, for which the input is acquired through a visual method, is built. Saturation of wheel–soil interaction image is adjusted by a dynamic piecewise nonlinear adjustment method The image is processed into a binary image based on HSI (Hue, Saturation, Intensity) color space. The wheel–soil boundary is extracted from the corrected wheel region outline according to its morphological features. The wheel Sinkage and equivalent terrain interface angles are calculated through the discrete mathematical wheel Sinkage calculation model. Sinkage definition rationality and detection method applicability are experimentally validated in the four typical terrain conditions (flat, bulgy, sunken, and uneven terrains). Particularly, the experimental results prove the Sinkage detection method has high accuracy for flat terrain, for which, the deviation of the Sinkage modulus is less than 2% of the wheel radius. The Sinkage detection method is proved to have fairly reasonable adaptability to complex illumination conditions, based on the experimental results for different illumination conditions.
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Terramechanics-based modeling of Sinkage and moment for in-situ steering wheels of mobile robots on deformable terrain
Mechanism and Machine Theory, 2017Co-Authors: Liang Ding, Haibo Gao, Zongquan Deng, Li Ningxi, Huaiguang Yang, Junlong Guo, Li NanAbstract:Abstract The success of NASA's Mars missions has generated a renewed interest in planetary exploration, along with a need for better mobility of wheeled mobile robots (WMRs)—steering performance, in particular, has not yet reached an acceptable benchmark in high-precision models. This study focuses on the steering mechanics of WMRs, as it can enrich the terramechanics of planetary rovers. An improved Sinkage model based on the variable Sinkage exponent is proposed, and the Sinkage exponent is derived as a function of steering angle. Furthermore, a high-precision steering moment model is proposed based on the steering-Sinkage model, which considers the interaction area and the lug effect. The model can fit the results obtained by all of the experimental wheels, based on soil parameter identification. Most of the max relative errors (MREs) for the Sinkage are within 5%, and the coefficients of determination are more than 0.97. The MREs of moment increase with increasing vertical load but remain within 10%. This technique can also be applied to other WMRs with rigid wheels steering on deformable terrain.
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Longitudinal skid model for wheels of planetary rovers based on improved wheel Sinkage considering soil bulldozing effect
Journal of Terramechanics, 2017Co-Authors: Junlong Guo, Liang Ding, Haibo Gao, Zongquan Deng, Tianyou Guo, Zhen LiuAbstract:Abstract To successfully deploy a wheeled mobile robot on deformable rough terrains, the wheel-terrain interaction mechanics should be considered. Skid terramechanics is an essential part of the wheel terramechanics and has been studied by the authors based on the wheel Sinkage obtained using a linear displacement sensor that does not consider soil bulldozing effect. The Sinkage measured by a newly developed wheel via detecting the entrance angle is about 2 times of that measured by the linear displacement sensor. On the basis of the wheel Sinkage that takes the soil bulldozing effect into account, a linear function is proposed to the Sinkage exponent. Soil flow in the rear region of wheel-soil interface is considered in the calculation of soil shear displacement, and its average velocity is assumed to be equal to the tangential velocity component of the transition point of shear stress. To compute the normal stress in the rear region directly, the connection of the entrance and leaving points is supposed as the reference of wheel Sinkage. The wheel performance can be accurately estimated using the proposed model by comparing the simulation results against the experimental data obtained using two wheels and on two types of sands.
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Planetary Rovers' Wheel Sinkage Detection Based on Wheel-Soil Boundary
Proceedings of the 2015 International Conference on Electrical Computer Engineering and Electronics, 2015Co-Authors: Li Nan, Liang Ding, Haibo Gao, Zongquan Deng, Zhen Liu, Song Xingguo, Bing YanAbstract:The detection of wheel Sinkage has great significance for rover mobility optimization control and prevention of wheel sinking. A new wheel Sinkage detection method is proposed based on planetary rovers' wheel-soil boundary. The model of wheel Sinkage calculation is built. The machine vision method is proposed to extract wheel-soil boundary. Wheel-soil interaction image is processed into binary image, and the wheel-soil boundary is extracted according to its morphological features. The wheel Sinkage depth, entrance angle and departure angle are calculated through the model of wheel Sinkage calculation. The method's applicability has been validated by experiments under various terrain conditions, which are flat terrain, raised terrain, hollow terrain, and rough terrain. Accuracy tests are done with the flat terrain, the results of the experiments indicate that the relative errors of the Sinkage depth are around 10% and the relative errors of terrain interface angles are around 5%, when the actual Sinkage depth is above 5mm.
Haibo Gao - One of the best experts on this subject based on the ideXlab platform.
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Sinkage definition and visual detection for planetary rovers wheels on rough terrain based on wheel soil interaction boundary
Robotics and Autonomous Systems, 2017Co-Authors: Haibo Gao, Liang Ding, Baofeng Yuan, Guangjun Liu, Zongquan DengAbstract:Abstract Wheel Sinkage detection is of tremendous significance for planetary rover mobility optimization control and prevention of serious wheel sinking. Wheel Sinkage is regarded as the distance between the lowest point of the wheel in the soil and the horizontal flat terrain on relative research. For rovers moving on rough terrains, the above definition is not reasonable because the horizontal flat terrain cannot be found. New wheel Sinkage definition and detection method are proposed, based on vision. The Sinkage definition rationality is analyzed for various terrain conditions. The discrete mathematical wheel Sinkage calculation model, for which the input is acquired through a visual method, is built. Saturation of wheel–soil interaction image is adjusted by a dynamic piecewise nonlinear adjustment method The image is processed into a binary image based on HSI (Hue, Saturation, Intensity) color space. The wheel–soil boundary is extracted from the corrected wheel region outline according to its morphological features. The wheel Sinkage and equivalent terrain interface angles are calculated through the discrete mathematical wheel Sinkage calculation model. Sinkage definition rationality and detection method applicability are experimentally validated in the four typical terrain conditions (flat, bulgy, sunken, and uneven terrains). Particularly, the experimental results prove the Sinkage detection method has high accuracy for flat terrain, for which, the deviation of the Sinkage modulus is less than 2% of the wheel radius. The Sinkage detection method is proved to have fairly reasonable adaptability to complex illumination conditions, based on the experimental results for different illumination conditions.
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Sinkage definition and visual detection for planetary rovers wheels on rough terrain based on wheel–soil interaction boundary
Robotics and Autonomous Systems, 2017Co-Authors: Haibo Gao, Liang Ding, Baofeng Yuan, Li Nan, Li Ningxi, Guangjun Liu, Zongquan DengAbstract:Abstract Wheel Sinkage detection is of tremendous significance for planetary rover mobility optimization control and prevention of serious wheel sinking. Wheel Sinkage is regarded as the distance between the lowest point of the wheel in the soil and the horizontal flat terrain on relative research. For rovers moving on rough terrains, the above definition is not reasonable because the horizontal flat terrain cannot be found. New wheel Sinkage definition and detection method are proposed, based on vision. The Sinkage definition rationality is analyzed for various terrain conditions. The discrete mathematical wheel Sinkage calculation model, for which the input is acquired through a visual method, is built. Saturation of wheel–soil interaction image is adjusted by a dynamic piecewise nonlinear adjustment method The image is processed into a binary image based on HSI (Hue, Saturation, Intensity) color space. The wheel–soil boundary is extracted from the corrected wheel region outline according to its morphological features. The wheel Sinkage and equivalent terrain interface angles are calculated through the discrete mathematical wheel Sinkage calculation model. Sinkage definition rationality and detection method applicability are experimentally validated in the four typical terrain conditions (flat, bulgy, sunken, and uneven terrains). Particularly, the experimental results prove the Sinkage detection method has high accuracy for flat terrain, for which, the deviation of the Sinkage modulus is less than 2% of the wheel radius. The Sinkage detection method is proved to have fairly reasonable adaptability to complex illumination conditions, based on the experimental results for different illumination conditions.
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Terramechanics-based modeling of Sinkage and moment for in-situ steering wheels of mobile robots on deformable terrain
Mechanism and Machine Theory, 2017Co-Authors: Liang Ding, Haibo Gao, Zongquan Deng, Li Ningxi, Huaiguang Yang, Junlong Guo, Li NanAbstract:Abstract The success of NASA's Mars missions has generated a renewed interest in planetary exploration, along with a need for better mobility of wheeled mobile robots (WMRs)—steering performance, in particular, has not yet reached an acceptable benchmark in high-precision models. This study focuses on the steering mechanics of WMRs, as it can enrich the terramechanics of planetary rovers. An improved Sinkage model based on the variable Sinkage exponent is proposed, and the Sinkage exponent is derived as a function of steering angle. Furthermore, a high-precision steering moment model is proposed based on the steering-Sinkage model, which considers the interaction area and the lug effect. The model can fit the results obtained by all of the experimental wheels, based on soil parameter identification. Most of the max relative errors (MREs) for the Sinkage are within 5%, and the coefficients of determination are more than 0.97. The MREs of moment increase with increasing vertical load but remain within 10%. This technique can also be applied to other WMRs with rigid wheels steering on deformable terrain.
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Longitudinal skid model for wheels of planetary rovers based on improved wheel Sinkage considering soil bulldozing effect
Journal of Terramechanics, 2017Co-Authors: Junlong Guo, Liang Ding, Haibo Gao, Zongquan Deng, Tianyou Guo, Zhen LiuAbstract:Abstract To successfully deploy a wheeled mobile robot on deformable rough terrains, the wheel-terrain interaction mechanics should be considered. Skid terramechanics is an essential part of the wheel terramechanics and has been studied by the authors based on the wheel Sinkage obtained using a linear displacement sensor that does not consider soil bulldozing effect. The Sinkage measured by a newly developed wheel via detecting the entrance angle is about 2 times of that measured by the linear displacement sensor. On the basis of the wheel Sinkage that takes the soil bulldozing effect into account, a linear function is proposed to the Sinkage exponent. Soil flow in the rear region of wheel-soil interface is considered in the calculation of soil shear displacement, and its average velocity is assumed to be equal to the tangential velocity component of the transition point of shear stress. To compute the normal stress in the rear region directly, the connection of the entrance and leaving points is supposed as the reference of wheel Sinkage. The wheel performance can be accurately estimated using the proposed model by comparing the simulation results against the experimental data obtained using two wheels and on two types of sands.
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Planetary Rovers' Wheel Sinkage Detection Based on Wheel-Soil Boundary
Proceedings of the 2015 International Conference on Electrical Computer Engineering and Electronics, 2015Co-Authors: Li Nan, Liang Ding, Haibo Gao, Zongquan Deng, Zhen Liu, Song Xingguo, Bing YanAbstract:The detection of wheel Sinkage has great significance for rover mobility optimization control and prevention of wheel sinking. A new wheel Sinkage detection method is proposed based on planetary rovers' wheel-soil boundary. The model of wheel Sinkage calculation is built. The machine vision method is proposed to extract wheel-soil boundary. Wheel-soil interaction image is processed into binary image, and the wheel-soil boundary is extracted according to its morphological features. The wheel Sinkage depth, entrance angle and departure angle are calculated through the model of wheel Sinkage calculation. The method's applicability has been validated by experiments under various terrain conditions, which are flat terrain, raised terrain, hollow terrain, and rough terrain. Accuracy tests are done with the flat terrain, the results of the experiments indicate that the relative errors of the Sinkage depth are around 10% and the relative errors of terrain interface angles are around 5%, when the actual Sinkage depth is above 5mm.
