All-position robots are widely applied in the welding of complicated parts.Welding of intersecting pipes is one of the most typical tasks.The welding seam is a complicated saddle-like space curve,which puts a great ch...All-position robots are widely applied in the welding of complicated parts.Welding of intersecting pipes is one of the most typical tasks.The welding seam is a complicated saddle-like space curve,which puts a great challenge to the pose planning of end-effector.The special robots designed specifically for this kind of tasks are rare in China and lack sufficient theoretical research.In this paper,a systematic research on the pose planning for the end-effectors of robot in the welding of intersecting pipes is conducted. First,the intersecting curve of pipes is mathematically analyzed.The mathematical model of the most general intersecting curve of pipes is derived,and several special forms of this model in degraded situations are also discussed.A new pose planning approach of bisecting angle in main normal plane（BAMNP） for the welding-gun is proposed by using differential geometry and the comparison with the traditional bisecting angle in axial rotation plane（BAARP） method is also analytically conducted.The optimal pose of the welding-gun is to make the orientation posed at the center of the small space formed by the two cylinders and the intersecting curve to help the welding-pool run smoothly.The BAMNP method can make sure the pose vertical to the curve and center between the two cylinders at the same time,therefore its performance in welding-technique is superior to the BAARP method.By using the traditional BAARP method,the robot structure can become simpler and easier to be controlled,because one degree of freedom（DOF） of the robot can be reduced.For the special case of perpendicular intersecting,an index is constructed to evaluate the quality of welding technique in the process of welding.The effect of different combination of pipe size on this index is also discussed.On the basis of practical consideration,selection principle for BAARP and BAMNP is described.The simulations of those two methods for a serial joint-type robot are made in MATLAB,and the simulation results are consistent to the analys展开更多
目的:探讨改良式硅橡胶印模定位平行投照技术的临床运用。方法:选取24例牙周炎牙周治疗患者及 24例牙体牙髓科根管治疗的患者,分别进行硅橡胶印模定位平行投照和分角线投照,分别测量数字式根尖片上沿牙长轴方向的牙体长度(L)及釉牙骨质...目的:探讨改良式硅橡胶印模定位平行投照技术的临床运用。方法:选取24例牙周炎牙周治疗患者及 24例牙体牙髓科根管治疗的患者,分别进行硅橡胶印模定位平行投照和分角线投照,分别测量数字式根尖片上沿牙长轴方向的牙体长度(L)及釉牙骨质界牙体宽度(W),按照牙位分为前牙+上颌磨牙组和下颌磨牙组,使用SPSS 22.0软件进行配对 t 检验及相关性分析比较2种投照技术2次投照的差异。结果:虽然两种投照技术前后2次投照的牙体长度及宽度的配对 t 检验均不具有显著性差异( P >0.05),但是与分角线投照技术相比,改良式硅橡胶印模定位平行投照技术所得到的前后两次根尖片上的牙体长度和宽度的组内相关系数更高。结论:改良式硅橡胶印模定位投照技术是一种稳定可靠、可操作性强的根尖片投照技术,适用于需要进行纵向定量对比的各类口腔科疾病诊断和分析。展开更多
基金supported by National Nautural Science Foundation of China(Grant No.50775002)Key Science and Technology Research Program of Beijing Municipal Commission of Education of China(Grant No.KZ200910005003)
文摘All-position robots are widely applied in the welding of complicated parts.Welding of intersecting pipes is one of the most typical tasks.The welding seam is a complicated saddle-like space curve,which puts a great challenge to the pose planning of end-effector.The special robots designed specifically for this kind of tasks are rare in China and lack sufficient theoretical research.In this paper,a systematic research on the pose planning for the end-effectors of robot in the welding of intersecting pipes is conducted. First,the intersecting curve of pipes is mathematically analyzed.The mathematical model of the most general intersecting curve of pipes is derived,and several special forms of this model in degraded situations are also discussed.A new pose planning approach of bisecting angle in main normal plane（BAMNP） for the welding-gun is proposed by using differential geometry and the comparison with the traditional bisecting angle in axial rotation plane（BAARP） method is also analytically conducted.The optimal pose of the welding-gun is to make the orientation posed at the center of the small space formed by the two cylinders and the intersecting curve to help the welding-pool run smoothly.The BAMNP method can make sure the pose vertical to the curve and center between the two cylinders at the same time,therefore its performance in welding-technique is superior to the BAARP method.By using the traditional BAARP method,the robot structure can become simpler and easier to be controlled,because one degree of freedom（DOF） of the robot can be reduced.For the special case of perpendicular intersecting,an index is constructed to evaluate the quality of welding technique in the process of welding.The effect of different combination of pipe size on this index is also discussed.On the basis of practical consideration,selection principle for BAARP and BAMNP is described.The simulations of those two methods for a serial joint-type robot are made in MATLAB,and the simulation results are consistent to the analys
文摘目的:探讨改良式硅橡胶印模定位平行投照技术的临床运用。方法:选取24例牙周炎牙周治疗患者及 24例牙体牙髓科根管治疗的患者,分别进行硅橡胶印模定位平行投照和分角线投照,分别测量数字式根尖片上沿牙长轴方向的牙体长度(L)及釉牙骨质界牙体宽度(W),按照牙位分为前牙+上颌磨牙组和下颌磨牙组,使用SPSS 22.0软件进行配对 t 检验及相关性分析比较2种投照技术2次投照的差异。结果:虽然两种投照技术前后2次投照的牙体长度及宽度的配对 t 检验均不具有显著性差异( P >0.05),但是与分角线投照技术相比,改良式硅橡胶印模定位平行投照技术所得到的前后两次根尖片上的牙体长度和宽度的组内相关系数更高。结论:改良式硅橡胶印模定位投照技术是一种稳定可靠、可操作性强的根尖片投照技术,适用于需要进行纵向定量对比的各类口腔科疾病诊断和分析。
