The existing kinematic parameter calibration method cannot further improve the absolute positioning accuracy of the robot due to the uncertainty of positioning error caused by robot joint backlash.In view of this prob...The existing kinematic parameter calibration method cannot further improve the absolute positioning accuracy of the robot due to the uncertainty of positioning error caused by robot joint backlash.In view of this problem,a closed‑loop feedback accuracy compensation method for robot joints was proposed.Firstly,a Chebyshev polynomial error estimation model was established which took geometric error and non‑geometric error into account.In addition,the absolute linear grating scale was installed at each joint of the robot and the positioning error of the robot end was mapped to the joint angle.And the joint angle corrected value was obtained.Furthermore,the closed‑loop feedback of robot joints was established to realize the online correction of the positioning error.Finally,an experiment on the KUKA KR210 industrial robot was conducted to demonstrate the effectiveness of the method.The result shows that the maximum absolute positioning error of the robot is reduced by 75%from 0.76 mm to 0.19 mm.This method can compensate the robot joint backlash effectively and further improve the absolute positioning accuracy of the robot.展开更多
In this manuscript, the authors have studied the Disc Displacement (DD) status of patients with acute Closed Lock (CL) to determine differences between DD with Reduction (DDwR) and DD without Reduction (DDwoR). Among ...In this manuscript, the authors have studied the Disc Displacement (DD) status of patients with acute Closed Lock (CL) to determine differences between DD with Reduction (DDwR) and DD without Reduction (DDwoR). Among the acute CL patients who visited our hospital within 2 weeks of the onset of CL, we studied 10 patients whose CL was released (DDwR) and 13 patients whose CL was not released (DDwoR). The DDwoR group was significantly older than the DDwR group. Although the mouth opening distance was significantly greater in the DDwoR group than in the DDwR group, the two groups were identical in the duration of CL. Sagittal MRI images showed no significant differences between the two groups in disc length and disc thickness (anterior band, intermediate zone, and posterior band). Multisection sagittal and coronal images identified lateral DD in 7 of the 10 patients in the DDwR group, although no specific direction of the DD was observed in the DDwoR group. Furthermore, deformation of the medial disc was common in the DDwoR group but uncommon in the DDwR group.展开更多
The relationship between the stability and the configuration of the driving joint was studied as a measure to improve the stability of robot.The Lagrange dynamic equation of the robot was established.According to the ...The relationship between the stability and the configuration of the driving joint was studied as a measure to improve the stability of robot.The Lagrange dynamic equation of the robot was established.According to the principle of virtual work,the least squares solution of each joint torque was obtained.The relationship between the stability of the robot and the configuration of the driving joint is obtained by the sum of the norms of the joint torque.Finally,numerical simulations verify the correctness of the theory.展开更多
目的比较经后外侧入路由后向前三枚空心螺钉三角分布固定与钢板固定治疗累及关节面≥25%后踝骨折的临床疗效。方法回顾性分析南京大学医学院附属苏州医院2016年5月至2022年5月行外科手术治疗的63例后踝骨折患者的临床资料,其中33例行三...目的比较经后外侧入路由后向前三枚空心螺钉三角分布固定与钢板固定治疗累及关节面≥25%后踝骨折的临床疗效。方法回顾性分析南京大学医学院附属苏州医院2016年5月至2022年5月行外科手术治疗的63例后踝骨折患者的临床资料,其中33例行三枚空心螺钉三角分布固定(空心钉组),30例行钢板固定(钢板组)。比较两组患者的术中出血量、手术时间、骨折愈合时间、并发症发生率,以及术后6、12个月及末次随访时踝关节功能评分(American Orthopaedic Foot and Ankle Society,AOFAS)和踝关节活动度(range of motion,ROM)。结果63例患者均得到随访,随访时间为12~48个月,平均(20.5±2.1)个月。两组患者在平均手术时间及并发症发生率方面比较,差异有统计学意义(P<0.05),平均手术时间空心钉组短于钢板组,并发症发生率空心钉组(3.03%)低于钢板组(13.33%);而两组患者的术中出血量及后踝骨折愈合时间比较,差异无统计学意义(P>0.05)。末次随访时优良率比较,空心钉组(90.9%)与钢板组(90.0%)差异无统计学意义(P>0.05)。两组患者随访期间均未出现切口感染、内固定物松动、退出、骨不连等并发症。结论两种方法在治疗此类后踝骨折中均可取得良好的临床疗效,而空心螺钉三角分布固定具有创伤小、并发症少及易于取出等众多优点,是此类后踝骨折内固定有效且经济的方法选择。展开更多
Cape Stone Forest is a group of granite rock pillars(pedestal rocks) towering over Shilin Lake, on the southern shore of Shantou Bay in eastern Guangdong, China. The rock pillars were previously identified as sea stac...Cape Stone Forest is a group of granite rock pillars(pedestal rocks) towering over Shilin Lake, on the southern shore of Shantou Bay in eastern Guangdong, China. The rock pillars were previously identified as sea stacks because they have marine notch-like concave sidewalls at their base, and more importantly, the lake is immediately adjacent to the bay, which is exposed to the open sea. However, rock pillars similar in shape and size can also be found at the top of Queshi Mountain, which is only about 300 meters northwest of the lake and about 85 meters above sea level. Therefore, the marine origin of Cape Stone Forest is seriously questioned. In this study, 3D imagery and drone technology were used to collect data in the investigations without direct manual measurements in the water or on the mountain. It shows that the concave sidewalls of the rock pillars in the lake and on the mountains occur at different heights and are exposed to different directions, while a natural sea stack on Mayu Island at the mouth of Shantou Bay has a horizontal notch parallel to the sea level, although the granite rock of the sea stack is the same as that of the lake and the mountains. The eastern side of the island, where the sea stack is located, is exposed to the open sea but blocks large waves for the rock pillars in the lake. Therefore, the origin of Cape Stone Forest cannot be explained by wave-based mechanisms. The only satisfactory explanation that takes into account all the field evidence is that the narrow rock pillars of the lake and mountain were formed by chemical weathering that penetrated closely the spaced joints of the granite rock, and the notch-like concave sidewalls were formed by more effective chemical weathering at the base of the pillars.展开更多
Subtalar dislocation is described as the simultaneous dislocation of the talo-calcaneal and talo-navicular joints without any tibio-talar or talar neck associated fractures. This injury is rare, and represents 1% of d...Subtalar dislocation is described as the simultaneous dislocation of the talo-calcaneal and talo-navicular joints without any tibio-talar or talar neck associated fractures. This injury is rare, and represents 1% of dislocations. We report the case of 28-year-old male patient, without any medical history, who had been involved in a sport accident causing a rare closed external subtalar dislocation without any bone fracture. An open reduction was indicated after failure of closed reduction and the X-ray control showed good joint congruence;the fixation was maintained for 6 weeks and then the rehabilitation was started. The evaluation was favorable, and we noted good functional results after a decline of 12 months.展开更多
基金supported by the National Natural Science Foundation of China(Nos.51875287, 52075250)the Special Fund for Transformation of Scientific,and Technological Achievements of Jiangsu Province(No.BA2018053)
文摘The existing kinematic parameter calibration method cannot further improve the absolute positioning accuracy of the robot due to the uncertainty of positioning error caused by robot joint backlash.In view of this problem,a closed‑loop feedback accuracy compensation method for robot joints was proposed.Firstly,a Chebyshev polynomial error estimation model was established which took geometric error and non‑geometric error into account.In addition,the absolute linear grating scale was installed at each joint of the robot and the positioning error of the robot end was mapped to the joint angle.And the joint angle corrected value was obtained.Furthermore,the closed‑loop feedback of robot joints was established to realize the online correction of the positioning error.Finally,an experiment on the KUKA KR210 industrial robot was conducted to demonstrate the effectiveness of the method.The result shows that the maximum absolute positioning error of the robot is reduced by 75%from 0.76 mm to 0.19 mm.This method can compensate the robot joint backlash effectively and further improve the absolute positioning accuracy of the robot.
文摘In this manuscript, the authors have studied the Disc Displacement (DD) status of patients with acute Closed Lock (CL) to determine differences between DD with Reduction (DDwR) and DD without Reduction (DDwoR). Among the acute CL patients who visited our hospital within 2 weeks of the onset of CL, we studied 10 patients whose CL was released (DDwR) and 13 patients whose CL was not released (DDwoR). The DDwoR group was significantly older than the DDwR group. Although the mouth opening distance was significantly greater in the DDwoR group than in the DDwR group, the two groups were identical in the duration of CL. Sagittal MRI images showed no significant differences between the two groups in disc length and disc thickness (anterior band, intermediate zone, and posterior band). Multisection sagittal and coronal images identified lateral DD in 7 of the 10 patients in the DDwR group, although no specific direction of the DD was observed in the DDwoR group. Furthermore, deformation of the medial disc was common in the DDwoR group but uncommon in the DDwR group.
文摘The relationship between the stability and the configuration of the driving joint was studied as a measure to improve the stability of robot.The Lagrange dynamic equation of the robot was established.According to the principle of virtual work,the least squares solution of each joint torque was obtained.The relationship between the stability of the robot and the configuration of the driving joint is obtained by the sum of the norms of the joint torque.Finally,numerical simulations verify the correctness of the theory.
文摘目的比较经后外侧入路由后向前三枚空心螺钉三角分布固定与钢板固定治疗累及关节面≥25%后踝骨折的临床疗效。方法回顾性分析南京大学医学院附属苏州医院2016年5月至2022年5月行外科手术治疗的63例后踝骨折患者的临床资料,其中33例行三枚空心螺钉三角分布固定(空心钉组),30例行钢板固定(钢板组)。比较两组患者的术中出血量、手术时间、骨折愈合时间、并发症发生率,以及术后6、12个月及末次随访时踝关节功能评分(American Orthopaedic Foot and Ankle Society,AOFAS)和踝关节活动度(range of motion,ROM)。结果63例患者均得到随访,随访时间为12~48个月,平均(20.5±2.1)个月。两组患者在平均手术时间及并发症发生率方面比较,差异有统计学意义(P<0.05),平均手术时间空心钉组短于钢板组,并发症发生率空心钉组(3.03%)低于钢板组(13.33%);而两组患者的术中出血量及后踝骨折愈合时间比较,差异无统计学意义(P>0.05)。末次随访时优良率比较,空心钉组(90.9%)与钢板组(90.0%)差异无统计学意义(P>0.05)。两组患者随访期间均未出现切口感染、内固定物松动、退出、骨不连等并发症。结论两种方法在治疗此类后踝骨折中均可取得良好的临床疗效,而空心螺钉三角分布固定具有创伤小、并发症少及易于取出等众多优点,是此类后踝骨折内固定有效且经济的方法选择。
基金funded by the Natural Science Foundation of China (Grants No. 42171007)。
文摘Cape Stone Forest is a group of granite rock pillars(pedestal rocks) towering over Shilin Lake, on the southern shore of Shantou Bay in eastern Guangdong, China. The rock pillars were previously identified as sea stacks because they have marine notch-like concave sidewalls at their base, and more importantly, the lake is immediately adjacent to the bay, which is exposed to the open sea. However, rock pillars similar in shape and size can also be found at the top of Queshi Mountain, which is only about 300 meters northwest of the lake and about 85 meters above sea level. Therefore, the marine origin of Cape Stone Forest is seriously questioned. In this study, 3D imagery and drone technology were used to collect data in the investigations without direct manual measurements in the water or on the mountain. It shows that the concave sidewalls of the rock pillars in the lake and on the mountains occur at different heights and are exposed to different directions, while a natural sea stack on Mayu Island at the mouth of Shantou Bay has a horizontal notch parallel to the sea level, although the granite rock of the sea stack is the same as that of the lake and the mountains. The eastern side of the island, where the sea stack is located, is exposed to the open sea but blocks large waves for the rock pillars in the lake. Therefore, the origin of Cape Stone Forest cannot be explained by wave-based mechanisms. The only satisfactory explanation that takes into account all the field evidence is that the narrow rock pillars of the lake and mountain were formed by chemical weathering that penetrated closely the spaced joints of the granite rock, and the notch-like concave sidewalls were formed by more effective chemical weathering at the base of the pillars.
文摘Subtalar dislocation is described as the simultaneous dislocation of the talo-calcaneal and talo-navicular joints without any tibio-talar or talar neck associated fractures. This injury is rare, and represents 1% of dislocations. We report the case of 28-year-old male patient, without any medical history, who had been involved in a sport accident causing a rare closed external subtalar dislocation without any bone fracture. An open reduction was indicated after failure of closed reduction and the X-ray control showed good joint congruence;the fixation was maintained for 6 weeks and then the rehabilitation was started. The evaluation was favorable, and we noted good functional results after a decline of 12 months.
