As the location of the wheel center is the key to accurately measuring the wheelbase, the wheelbase difference and the wheel static radius, a high-precision wheel center detection method based on stereo vision is prop...As the location of the wheel center is the key to accurately measuring the wheelbase, the wheelbase difference and the wheel static radius, a high-precision wheel center detection method based on stereo vision is proposed. First, according to the prior information, the contour of the wheel hub is extracted and fitted as an ellipse curve, and the ellipse fitting equation can be obtained. Then, a new un-tangent constraint is adopted to improve the ellipse matching precision. Finally, the 3D coordinates of the wheel center can be reconstructed by the spatial circle projection algorithm with low time complexity and high measurement accuracy. Simulation experiments verify that compared with the ellipse center reconstruction algorithm and the planar constraint optimization algorithm, the proposed method can acquire the 3D coordinates of the spatial circle more exactly. Furthermore, the measurements of the wheelbase, the wheelbase difference and the wheel static radius for three types of vehicles demonstrate the effectiveness of the proposed method for wheel center detection.展开更多
A coupled discrete-continuum simulation incorporating a 3D aspect and non-circular particles was performed to analyze soil-pile interactions during pile penetration in sand.A self-developed non-circular particle numer...A coupled discrete-continuum simulation incorporating a 3D aspect and non-circular particles was performed to analyze soil-pile interactions during pile penetration in sand.A self-developed non-circular particle numerical simulation program was used which considered sand near the pile as interacted particles using a discrete element method;the sand away from the pile was simulated as a continuous medium exhibiting linear elastic behaviors.The domain analyzed was divided into two zones.Contact forces at the interface between the two zones were obtained from a discrete zone and applied to the continuum boundaries as nodal forces,while the interface velocities were obtained from the continuum zone and applied to the discrete boundaries.We show that the coupled discrete-continuum simulation can give a microscopic description of the pile penetration process without losing the discrete nature of the zone concerned,and may significantly improve computational efficiency.展开更多
基金The National Natural Science Foundation of China(No.61272223)the National Key Scientific Apparatus Development of Special Item(No.2012YQ170003-5)
文摘As the location of the wheel center is the key to accurately measuring the wheelbase, the wheelbase difference and the wheel static radius, a high-precision wheel center detection method based on stereo vision is proposed. First, according to the prior information, the contour of the wheel hub is extracted and fitted as an ellipse curve, and the ellipse fitting equation can be obtained. Then, a new un-tangent constraint is adopted to improve the ellipse matching precision. Finally, the 3D coordinates of the wheel center can be reconstructed by the spatial circle projection algorithm with low time complexity and high measurement accuracy. Simulation experiments verify that compared with the ellipse center reconstruction algorithm and the planar constraint optimization algorithm, the proposed method can acquire the 3D coordinates of the spatial circle more exactly. Furthermore, the measurements of the wheelbase, the wheelbase difference and the wheel static radius for three types of vehicles demonstrate the effectiveness of the proposed method for wheel center detection.
基金Project (No.90815008) supported by the National Natural Science Foundation of China
文摘A coupled discrete-continuum simulation incorporating a 3D aspect and non-circular particles was performed to analyze soil-pile interactions during pile penetration in sand.A self-developed non-circular particle numerical simulation program was used which considered sand near the pile as interacted particles using a discrete element method;the sand away from the pile was simulated as a continuous medium exhibiting linear elastic behaviors.The domain analyzed was divided into two zones.Contact forces at the interface between the two zones were obtained from a discrete zone and applied to the continuum boundaries as nodal forces,while the interface velocities were obtained from the continuum zone and applied to the discrete boundaries.We show that the coupled discrete-continuum simulation can give a microscopic description of the pile penetration process without losing the discrete nature of the zone concerned,and may significantly improve computational efficiency.
