In the realm of quadruped robot locomotion,compliance control is imperative to handle impacts when negotiating unstructured terrains.At the same time,kinematic tracking accuracy should be guaranteed during locomotion....In the realm of quadruped robot locomotion,compliance control is imperative to handle impacts when negotiating unstructured terrains.At the same time,kinematic tracking accuracy should be guaranteed during locomotion.To meet both demands,ajoint space compliance controller is designed,so that compliance can be achieved in stance phase while position tracking performance can be guaranteed in swing phase.Unlike operational space compliance control,the joint space compliance control method is easy to implement and does not depend on robot dynamics.As for each joint actuator,high performance force control is of great importance for compliance design.Therefore,a nonlinear PI controller based on feedback linearization is proposed for the hydraulic actuator force control.Besides,an outer position loop（compliance loop）is closed for each joint.Experiments are carried out to verify the force controller and compliance of the hydraulic actuator.The robot leg compliance is assessed by a virtual prototyping simulation.展开更多
Assessing the radiographic features of knee osteoarthritis （OA）, especially joint space narrowing, is important for evaluating disease progression. The purpose of this study was to quantitatively analyze joint space...Assessing the radiographic features of knee osteoarthritis （OA）, especially joint space narrowing, is important for evaluating disease progression. The purpose of this study was to quantitatively analyze joint space narrowing by measuring 2 new variables： the average joint space width （aJSW） and the articulate angle （AA） on X-ray films, and to evaluate the relationship between the 2 variables, knee function and OA symptoms. Methods Using the web-based radiology viewer （Cedara I-ReachTM 4.1.1）, we measured the 2 variables in 50 knees of 41 patients with knee OA participating in the Shanghai OA Study. We also evaluated the Kellgren-Lawrence （K-L） grade, the Western Ontario and McMaster Universities OA Index （WOMAC）, and additional questionnaire in OA knees. The study was approved by the ethics committee of Shanghai Ninth People＇s Hospital （No. 2009-28）. Results The aJSW correlated with the K-L grade （r=-0.57, P 〈0.001）, kneeling （r=-0.29, P=0.04）, sitting cross-legged on the floor （r=-0.31, P=0.03）, WOMAC pain （r=-0.31, P=0.03）, WOMAC disability （r=-0.35, P=0.01）, pain while squatting （r=-0.37, P=0.01）, and defecating in a squatting position （r=-0.39, P= 0.01）. The AA correlated with defecating in a squatting position （r=0.29, P=0.05）, WOMAC disability （r=0.30, P=0.04） and K-L grade （r=0.44, P=0.003）. The K-L grade also correlated with pain while squatting （r=-0.40, P=0.005） and defecating in a squatting position （r=-0.34, P=0.02）, WOMAC pain （r=0.30, P=0.04）, and WOMAC disability （r=0.30, P=0.04）. Conclusions The aJSW closely correlated with knee OA symptoms and function scores, and was more sensitive to knee OA related disabilities than K-L grade and the AA. The aJSW could be used as a new variable for knee OA evaluation.展开更多
BACKGROUND The role of occlusal factors on the occurrence of temporomandibular joint disorders(TMDs)is still unclear and it is tricky for orthodontists to treat malocclusions in patients with TMDs.We report the case o...BACKGROUND The role of occlusal factors on the occurrence of temporomandibular joint disorders(TMDs)is still unclear and it is tricky for orthodontists to treat malocclusions in patients with TMDs.We report the case of the second orthodontic treatment of an adult female with Class II division 2 malocclusion associated with TMD.With the removal of anterior occlusal interference,TMD symptoms were alleviated and cone beam computed tomography(CBCT)images showed the bilateral condyles shifted forward.CASE SUMMARY This case report presented an orthodontic retreatment of an adult female with TMD and mandibular backward positioning based on CBCT examination and Joint Space Index(JSI)analysis.The left and right JSI values of-38.5 and-52.6 indicated that the position of bilateral condyles had posterior displacement.Ten years prior to this evaluation,she underwent orthodontic treatment resulting in the extraction of two upper premolars and one lower central incisor.The joint symptoms,including pain and sounds,were alleviated along with verified mandibular forward repositioning by extraction of another lower central incisor.CONCLUSION Mandibular backward positioning could be associated with TMD.JSI analysis based on CBCT is a convenient way to examine condylar positions quantitatively.展开更多
Background: Rheumatoid arthritis is a form of autoimmune disease characterized by synovitis that can ultimately cause joint deformities and impaired functioning. The cartilage destruction is one of the most important ...Background: Rheumatoid arthritis is a form of autoimmune disease characterized by synovitis that can ultimately cause joint deformities and impaired functioning. The cartilage destruction is one of the most important indicators for diagnosis and treatment of rheumatoid arthritis, and it is radiographically manifested as joint space narrowing. Issue: In the literature, the joint space narrowing progression between a baseline and its follow-up finger joint images can be quantified by using image registration algorithm. We found that the inconsistencies of joint angles may lead to characteristic mismatches and thus severely affect the accuracy of joint space narrowing quantifications. Methods: In this work, we introduce a rotation invariant phase only correlation in joint space narrowing quantification for the joint angle correction. Further, we propose a confidence index to quantify the quantification reliability of phase only correlation based on phase dispersion in phase difference spectrum. Conclusion: In our clinical experiments, the proposed quantification method can effectively overcome and manage the mismatch due to the inconsistency of joint angles. Additionally, the confidence index shows a high consistency with the joint space narrowing progression examinations manually done by a trained radiologist and one radiological technologist.展开更多
This paper describes the influence of joint spacing and joint orientation on the penetration rate of a Tunnel Boring Machine （TBM） disc cutter as modeled by the Discrete Element Method （DEM）. The input data for th...This paper describes the influence of joint spacing and joint orientation on the penetration rate of a Tunnel Boring Machine （TBM） disc cutter as modeled by the Discrete Element Method （DEM）. The input data for the siLmulations were obtained from the sandstone along the AIborz tunnel that is currently being excavated in Iran using a 5.2 m diameter open TBM. Three joint spacings, 150, 200, and 300 mm, were modeled together with seven values of joint orientation; 0°, 15°, 30°, 45°, 60°, 75°, and 90°. The results show that the penetration increases when joint orientation increases from 0° to 75°, but it decreases as the joint orientation increases further from 75° to 90°. This is true for each joint spacing. In addition, for a given joint orientation increasing the joint spacing causes the TBM penetration to decrease. The optimum joint orientation, from the viewpoint of TBM penetration, is about 60-75°.展开更多
The most commonly used method for assessing the hydraulic erodibility of rock is Annandale's method.This method is based on a correlation between the erosive force of flowing water and the capacity of rock resista...The most commonly used method for assessing the hydraulic erodibility of rock is Annandale's method.This method is based on a correlation between the erosive force of flowing water and the capacity of rock resistance. This capacity is evaluated using Kirsten's index, which was initially developed to evaluate the excavatability of earth materials. For rocky material, this index is determined according to certain geomechanical factors related to intact rock and rock mass, such as compressive strength of intact rock, rock block size, discontinuity shear strength and relative block structure. To quantify the relative block structure, Kirsten(1982) developed a mathematical expression that accounts for the shape and orientation of the blocks relative to the direction of flow. Kirsten's initial concept for assessing the relative block structure considers that the geological formation is mainly fractured by two joint sets forming an orthogonally fractured system. An adjusted concept is proposed to determine the relative block structure when the fractured system is non-orthogonal where the angle between the planes of the two joint sets is greater or less than 90°. An analysis of the proposed relative block structure rating shows that considering a non-orthogonally fractured system has a significant effect on Kirsten's index and, as a consequence, on the assessment of the hydraulic erodibility of rock.展开更多
This paper investigates the motion planning of redundant free-floating manipulators with seven prismatic joints. On the earth, prismatic-jointed manipulators could only position their end-effectors in a desired way. H...This paper investigates the motion planning of redundant free-floating manipulators with seven prismatic joints. On the earth, prismatic-jointed manipulators could only position their end-effectors in a desired way. However, in space, the end-effectors of free-floating manipulators can achieve both the desired orientation and desired position due to the dynamical coupling between manipulator and satellite movement, which is formally expressed by linear and angular momentum conservation laws. In this study, a tractable algorithm particle swarm optimization combined with differential evolution （PSODE） is provided to deal with the motion planning of redundant free-floating prismatic-jointed manipulators, which could avoid the pseudo inverse of the Jacobian matrix. The polynomial functions, as argument in sine functions are used to specify the joint paths. The co- efficients of the polynomials are optimized to achieve the desired end-effector orientation and position, and simulta- neously minimize the unit-mass-kinetic energy using the redundancy. Relevant simulations prove that this method pro- vides satisfactory smooth paths for redundant free-floating prismatic-jointed manipulators. This study could help to recognize the advantages of redundant prismatic-jointed space manipulators.展开更多
Toy play is a basic skill for a humanoid robot after it has joint attention(JA) ability. Because such skill is helpful for human-robot interaction and cooperation, we must realize this skill to enhance the robots comm...Toy play is a basic skill for a humanoid robot after it has joint attention(JA) ability. Because such skill is helpful for human-robot interaction and cooperation, we must realize this skill to enhance the robots communication ability with person. In this paper, we researched a toy play controlling strategy in JA space based on a virtual plate with a serial robot arm, which has five degrees of freedom(5-DoF). For this purpose, a reachable space of joint attention was constructed firstly. And then the toy play controlling strategy was proposed in details. Here we used a virtual plate to enhance the toy play effect. In order to realize this skill better, toy play energy and some restraining relations were analyzed. By contrasting the audio waveform in the experiments, good performance effect of toy play was demonstrated.展开更多
基金Supported by the National High Technology Research and Development Program of China(863 Program)(2011AA041002)
文摘In the realm of quadruped robot locomotion,compliance control is imperative to handle impacts when negotiating unstructured terrains.At the same time,kinematic tracking accuracy should be guaranteed during locomotion.To meet both demands,ajoint space compliance controller is designed,so that compliance can be achieved in stance phase while position tracking performance can be guaranteed in swing phase.Unlike operational space compliance control,the joint space compliance control method is easy to implement and does not depend on robot dynamics.As for each joint actuator,high performance force control is of great importance for compliance design.Therefore,a nonlinear PI controller based on feedback linearization is proposed for the hydraulic actuator force control.Besides,an outer position loop（compliance loop）is closed for each joint.Experiments are carried out to verify the force controller and compliance of the hydraulic actuator.The robot leg compliance is assessed by a virtual prototyping simulation.
文摘Assessing the radiographic features of knee osteoarthritis （OA）, especially joint space narrowing, is important for evaluating disease progression. The purpose of this study was to quantitatively analyze joint space narrowing by measuring 2 new variables： the average joint space width （aJSW） and the articulate angle （AA） on X-ray films, and to evaluate the relationship between the 2 variables, knee function and OA symptoms. Methods Using the web-based radiology viewer （Cedara I-ReachTM 4.1.1）, we measured the 2 variables in 50 knees of 41 patients with knee OA participating in the Shanghai OA Study. We also evaluated the Kellgren-Lawrence （K-L） grade, the Western Ontario and McMaster Universities OA Index （WOMAC）, and additional questionnaire in OA knees. The study was approved by the ethics committee of Shanghai Ninth People＇s Hospital （No. 2009-28）. Results The aJSW correlated with the K-L grade （r=-0.57, P 〈0.001）, kneeling （r=-0.29, P=0.04）, sitting cross-legged on the floor （r=-0.31, P=0.03）, WOMAC pain （r=-0.31, P=0.03）, WOMAC disability （r=-0.35, P=0.01）, pain while squatting （r=-0.37, P=0.01）, and defecating in a squatting position （r=-0.39, P= 0.01）. The AA correlated with defecating in a squatting position （r=0.29, P=0.05）, WOMAC disability （r=0.30, P=0.04） and K-L grade （r=0.44, P=0.003）. The K-L grade also correlated with pain while squatting （r=-0.40, P=0.005） and defecating in a squatting position （r=-0.34, P=0.02）, WOMAC pain （r=0.30, P=0.04）, and WOMAC disability （r=0.30, P=0.04）. Conclusions The aJSW closely correlated with knee OA symptoms and function scores, and was more sensitive to knee OA related disabilities than K-L grade and the AA. The aJSW could be used as a new variable for knee OA evaluation.
文摘BACKGROUND The role of occlusal factors on the occurrence of temporomandibular joint disorders(TMDs)is still unclear and it is tricky for orthodontists to treat malocclusions in patients with TMDs.We report the case of the second orthodontic treatment of an adult female with Class II division 2 malocclusion associated with TMD.With the removal of anterior occlusal interference,TMD symptoms were alleviated and cone beam computed tomography(CBCT)images showed the bilateral condyles shifted forward.CASE SUMMARY This case report presented an orthodontic retreatment of an adult female with TMD and mandibular backward positioning based on CBCT examination and Joint Space Index(JSI)analysis.The left and right JSI values of-38.5 and-52.6 indicated that the position of bilateral condyles had posterior displacement.Ten years prior to this evaluation,she underwent orthodontic treatment resulting in the extraction of two upper premolars and one lower central incisor.The joint symptoms,including pain and sounds,were alleviated along with verified mandibular forward repositioning by extraction of another lower central incisor.CONCLUSION Mandibular backward positioning could be associated with TMD.JSI analysis based on CBCT is a convenient way to examine condylar positions quantitatively.
文摘Background: Rheumatoid arthritis is a form of autoimmune disease characterized by synovitis that can ultimately cause joint deformities and impaired functioning. The cartilage destruction is one of the most important indicators for diagnosis and treatment of rheumatoid arthritis, and it is radiographically manifested as joint space narrowing. Issue: In the literature, the joint space narrowing progression between a baseline and its follow-up finger joint images can be quantified by using image registration algorithm. We found that the inconsistencies of joint angles may lead to characteristic mismatches and thus severely affect the accuracy of joint space narrowing quantifications. Methods: In this work, we introduce a rotation invariant phase only correlation in joint space narrowing quantification for the joint angle correction. Further, we propose a confidence index to quantify the quantification reliability of phase only correlation based on phase dispersion in phase difference spectrum. Conclusion: In our clinical experiments, the proposed quantification method can effectively overcome and manage the mismatch due to the inconsistency of joint angles. Additionally, the confidence index shows a high consistency with the joint space narrowing progression examinations manually done by a trained radiologist and one radiological technologist.
文摘目的 评价磁共振3D space序列在膝关节半月板放射状撕裂中的诊断价值,提高对此病的影像认识,为临床诊疗提供帮助。方法 回顾性分析29例经关节镜证实的膝关节半月板放射状撕裂患者的磁共振资料;对比常规磁共振2D序列与3D space序列在半月板放射状撕裂病变中的诊断效能,使用Fisher确切概率法对两种方法诊断半月板放射状撕裂的准确率进行比较。结果 3D space序列和常规2D序列诊断半月板放射状撕裂的准确率分别为96.7%(29/30)、80.0%(24/30),3D space序列诊断准确率高于常规2D序列,差异有统计学意义(P<0.05)。结论 3D space序列在半月板放射状撕裂的诊断中具有较高价值,其诊断效能优于2D序列。
文摘This paper describes the influence of joint spacing and joint orientation on the penetration rate of a Tunnel Boring Machine （TBM） disc cutter as modeled by the Discrete Element Method （DEM）. The input data for the siLmulations were obtained from the sandstone along the AIborz tunnel that is currently being excavated in Iran using a 5.2 m diameter open TBM. Three joint spacings, 150, 200, and 300 mm, were modeled together with seven values of joint orientation; 0°, 15°, 30°, 45°, 60°, 75°, and 90°. The results show that the penetration increases when joint orientation increases from 0° to 75°, but it decreases as the joint orientation increases further from 75° to 90°. This is true for each joint spacing. In addition, for a given joint orientation increasing the joint spacing causes the TBM penetration to decrease. The optimum joint orientation, from the viewpoint of TBM penetration, is about 60-75°.
基金the organizations that have funded this project:the Natural Sciences and Engineering Research Council of Canada(Grant No.498020-16)Hydro-Quebec(NC-525700)Mitacs Accelerate Program(Grant Ref.IT10008)
文摘The most commonly used method for assessing the hydraulic erodibility of rock is Annandale's method.This method is based on a correlation between the erosive force of flowing water and the capacity of rock resistance. This capacity is evaluated using Kirsten's index, which was initially developed to evaluate the excavatability of earth materials. For rocky material, this index is determined according to certain geomechanical factors related to intact rock and rock mass, such as compressive strength of intact rock, rock block size, discontinuity shear strength and relative block structure. To quantify the relative block structure, Kirsten(1982) developed a mathematical expression that accounts for the shape and orientation of the blocks relative to the direction of flow. Kirsten's initial concept for assessing the relative block structure considers that the geological formation is mainly fractured by two joint sets forming an orthogonally fractured system. An adjusted concept is proposed to determine the relative block structure when the fractured system is non-orthogonal where the angle between the planes of the two joint sets is greater or less than 90°. An analysis of the proposed relative block structure rating shows that considering a non-orthogonally fractured system has a significant effect on Kirsten's index and, as a consequence, on the assessment of the hydraulic erodibility of rock.
基金supported by the National Natural Science Foundation of China (11072122)
文摘This paper investigates the motion planning of redundant free-floating manipulators with seven prismatic joints. On the earth, prismatic-jointed manipulators could only position their end-effectors in a desired way. However, in space, the end-effectors of free-floating manipulators can achieve both the desired orientation and desired position due to the dynamical coupling between manipulator and satellite movement, which is formally expressed by linear and angular momentum conservation laws. In this study, a tractable algorithm particle swarm optimization combined with differential evolution （PSODE） is provided to deal with the motion planning of redundant free-floating prismatic-jointed manipulators, which could avoid the pseudo inverse of the Jacobian matrix. The polynomial functions, as argument in sine functions are used to specify the joint paths. The co- efficients of the polynomials are optimized to achieve the desired end-effector orientation and position, and simulta- neously minimize the unit-mass-kinetic energy using the redundancy. Relevant simulations prove that this method pro- vides satisfactory smooth paths for redundant free-floating prismatic-jointed manipulators. This study could help to recognize the advantages of redundant prismatic-jointed space manipulators.
基金supported by Hebei Province Natural Science Foundation for Youths (No. F2015402108)the Foundation for Young Scholars of Hebei Educational Committee (No. QN20131152)Handan Municipal Science and Technology Projects (No. 1421103054)
文摘Toy play is a basic skill for a humanoid robot after it has joint attention(JA) ability. Because such skill is helpful for human-robot interaction and cooperation, we must realize this skill to enhance the robots communication ability with person. In this paper, we researched a toy play controlling strategy in JA space based on a virtual plate with a serial robot arm, which has five degrees of freedom(5-DoF). For this purpose, a reachable space of joint attention was constructed firstly. And then the toy play controlling strategy was proposed in details. Here we used a virtual plate to enhance the toy play effect. In order to realize this skill better, toy play energy and some restraining relations were analyzed. By contrasting the audio waveform in the experiments, good performance effect of toy play was demonstrated.
