The job shop scheduli ng problem has been studied for decades and known as an NP-hard problem. The fl exible job shop scheduling problem is a generalization of the classical job sche duling problem that allows an oper...The job shop scheduli ng problem has been studied for decades and known as an NP-hard problem. The fl exible job shop scheduling problem is a generalization of the classical job sche duling problem that allows an operation to be processed on one machine out of a set of machines. The problem is to assign each operation to a machine and find a sequence for the operations on the machine in order that the maximal completion time of all operations is minimized. A genetic algorithm is used to solve the f lexible job shop scheduling problem. A novel gene coding method aiming at job sh op problem is introduced which is intuitive and does not need repairing process to validate the gene. Computer simulations are carried out and the results show the effectiveness of the proposed algorithm.展开更多
基于问题的学习(PBL:Problem Based Learning)是一个学习者主动构建知识的过程,强调以学生为中心,教师仅仅起到引导学生去进行建构性活动的角色。在PBL中,由教师根据课程要求和学生的基础知识预先定义一个不完整的或劣构的问题,让学生...基于问题的学习(PBL:Problem Based Learning)是一个学习者主动构建知识的过程,强调以学生为中心,教师仅仅起到引导学生去进行建构性活动的角色。在PBL中,由教师根据课程要求和学生的基础知识预先定义一个不完整的或劣构的问题,让学生进行研究,理论联系实际,运用已掌握的知识和技能厘清问题、分解问题并提出解决问题的可行方案,从而不仅使学生获取了知识,并且学会运用知识解决问题。本文对PBL理论进行了综述,总结了几个国外航空航天工程教育案例,在此基础上根据我国航天工程教育的现状,讨论了以小卫星作为航天工程教育载体的重要性,并探讨了PBL教学方法在航天工程教育中的推行途径。展开更多
It is crucial for implementing force/position control of robotic manipulator under the constraint of unknown environment to determine the force control and the position control directions. This paper presents an on l...It is crucial for implementing force/position control of robotic manipulator under the constraint of unknown environment to determine the force control and the position control directions. This paper presents an on line algorithm to real timely estimate the tangent and the normal vectors of the constraint surface based on the measured contact force under the consideration of frictional force. A fuzzy synthesis policy is proposed to coordinate the conflict between the compliant force control and the stiff position control. An experimental study on an AdeptThree, a SCARA type robotic manipulator, is conducted. The experimental results show that the policy presented in the paper is effective.展开更多
A force control strategy for position controlled robotic manipulators is presented. On line force feedback data are employed to estimate the local shape of the unknown constraint. The estimated vectors are used to ge...A force control strategy for position controlled robotic manipulators is presented. On line force feedback data are employed to estimate the local shape of the unknown constraint. The estimated vectors are used to generate the virtual reference trajectory for the target impedance model that is driven by the force error to produce command position. By following the command position trajectory the robotic manipulator can follow the unknown constraint surface while keeping an acceptable force error in a manner depicted by the target impedance model. Computer simulation on a 3 linked planar manipulator and experimental studies on an Adept 3, an SCARA type robotic manipulator, are conducted to verify the force tracking capability of the proposed control strategy.展开更多
文摘The job shop scheduli ng problem has been studied for decades and known as an NP-hard problem. The fl exible job shop scheduling problem is a generalization of the classical job sche duling problem that allows an operation to be processed on one machine out of a set of machines. The problem is to assign each operation to a machine and find a sequence for the operations on the machine in order that the maximal completion time of all operations is minimized. A genetic algorithm is used to solve the f lexible job shop scheduling problem. A novel gene coding method aiming at job sh op problem is introduced which is intuitive and does not need repairing process to validate the gene. Computer simulations are carried out and the results show the effectiveness of the proposed algorithm.
文摘基于问题的学习(PBL:Problem Based Learning)是一个学习者主动构建知识的过程,强调以学生为中心,教师仅仅起到引导学生去进行建构性活动的角色。在PBL中,由教师根据课程要求和学生的基础知识预先定义一个不完整的或劣构的问题,让学生进行研究,理论联系实际,运用已掌握的知识和技能厘清问题、分解问题并提出解决问题的可行方案,从而不仅使学生获取了知识,并且学会运用知识解决问题。本文对PBL理论进行了综述,总结了几个国外航空航天工程教育案例,在此基础上根据我国航天工程教育的现状,讨论了以小卫星作为航天工程教育载体的重要性,并探讨了PBL教学方法在航天工程教育中的推行途径。
文摘It is crucial for implementing force/position control of robotic manipulator under the constraint of unknown environment to determine the force control and the position control directions. This paper presents an on line algorithm to real timely estimate the tangent and the normal vectors of the constraint surface based on the measured contact force under the consideration of frictional force. A fuzzy synthesis policy is proposed to coordinate the conflict between the compliant force control and the stiff position control. An experimental study on an AdeptThree, a SCARA type robotic manipulator, is conducted. The experimental results show that the policy presented in the paper is effective.
文摘A force control strategy for position controlled robotic manipulators is presented. On line force feedback data are employed to estimate the local shape of the unknown constraint. The estimated vectors are used to generate the virtual reference trajectory for the target impedance model that is driven by the force error to produce command position. By following the command position trajectory the robotic manipulator can follow the unknown constraint surface while keeping an acceptable force error in a manner depicted by the target impedance model. Computer simulation on a 3 linked planar manipulator and experimental studies on an Adept 3, an SCARA type robotic manipulator, are conducted to verify the force tracking capability of the proposed control strategy.
