Repeated bending occurs toward the direction of rail head and rail base during the cooling which can lead to significant bending deformation and residual stress after cooling.The longer the rail is,the more obvious th...Repeated bending occurs toward the direction of rail head and rail base during the cooling which can lead to significant bending deformation and residual stress after cooling.The longer the rail is,the more obvious this phenomenon is.In addition to cooling function,a kind of cooling bed with a pre-bending process is used in order to solve this problem on 100 m rail.The synchronous movements on this cooling bed can be realized by the automatic control system after establishing the mathematical model of bending deformation after rolling.The rail is reversely bent toward the rail base before cooling according to the pre-bending control of the pre-bending curve and is straight after cooling,which can realize the control of the residual stress after pre-bending and straightening.The straightening residual stress is significantly reduced after the pre-bending.展开更多
Robotic fingers, which are the key parts of robot hand, are divided into two main kinds： dexterous fingers and under-actuated fingers. Although dexterous fingers are agile, they are too expensive. Under-actuated fing...Robotic fingers, which are the key parts of robot hand, are divided into two main kinds： dexterous fingers and under-actuated fingers. Although dexterous fingers are agile, they are too expensive. Under-actuated fingers can grasp objects self-adaptively, which makes them easy to control and low cost, on the contrary, under-actuated function makes fingers feel hard to grasp things agilely enough and make many gestures. For the purpose of designing a new finger which can grasp things dexterously, perform many gestures and feel easy to control and maintain, a concept called ＂gesture-changeable under-actuated＂ （GCUA） function is put forward. The GCUA function combines the advantages of dexterous fingers and under-actuated fingers： a pre-bending function is embedded into the under-actuated finger. The GCUA finger can not only perform self-adaptive grasping function, but also actively bend the middle joint of the finger. On the basis of the concept, a GCUA finger with 2 joints is designed, which is realized by the coordination of screw-nut transmission mechanism, flexible drawstring constraint and pulley-belt under-actuated mechanism. Principle analyses of its grasping and the design optimization of the GCUA finger are given. An important problem of how to stably grasp an object which is easy to glide is discussed. The force analysis on gliding object in grasping process is introduced in detail. A GCUA finger with 3 joints is developed. Many experiments of grasping different objects by of the finger were carried out. The experimental results show that the GCUA finger can effectively realize functions of pre-bending and self-adaptive grasping, the grasping processes are stable. The GCUA finger excels under-actuated fingers in dexterity and gesture actions and it is easier to control and cheaper than dexterous hands, becomes the third kinds of finger.展开更多
The application of soft pneumatic actuators is typically hindered by the low strength and slow response speed caused by their intrinsic material limitation and unstressed stable form.In this work,we present a design s...The application of soft pneumatic actuators is typically hindered by the low strength and slow response speed caused by their intrinsic material limitation and unstressed stable form.In this work,we present a design strategy for improving the performance and response speed for Pneu-Nets actuators by incorporating adjustable elastic components to form the elastic composite pneumatic actuator(ECPA).The elastic energy storage of the elastic component is implemented to enhance the capability and speed up the response of ECPA and pre-bend the actuator.Due to the design principle,the fully-flexible ECPA is easy to manufacture and regulate.Theoretical modeling and experiments are implemented to reveal the fast response characteristics and adjustable mechanical characteristics of ECPA.Experimental results show that the deflation response speed of ECPA is increased by at least 3.1 times with the action of elastic components,what is more,the stiffness of ECPA is increased by 22 times.Based on the ECPA,two kinds of locomotion robots including a running robot(runs at an average locomotion speed of 6.3 BL/s(body lengths,BL))and an underwater swimming robot(achieves an average speed of 1.1 BL/s)are designed.The fast-moving robots both demonstrate high-speed mobility because of the rapid response and high strength of ECPA.展开更多
基金the National Natural Science Foundation of China (No.50765004)
文摘Repeated bending occurs toward the direction of rail head and rail base during the cooling which can lead to significant bending deformation and residual stress after cooling.The longer the rail is,the more obvious this phenomenon is.In addition to cooling function,a kind of cooling bed with a pre-bending process is used in order to solve this problem on 100 m rail.The synchronous movements on this cooling bed can be realized by the automatic control system after establishing the mathematical model of bending deformation after rolling.The rail is reversely bent toward the rail base before cooling according to the pre-bending control of the pre-bending curve and is straight after cooling,which can realize the control of the residual stress after pre-bending and straightening.The straightening residual stress is significantly reduced after the pre-bending.
基金supported by National Natural Science Foundation of China (No. 50905093)National Hi-tech Research and Development Program of China(863 Program,Grant No.2007AA04Z258)
文摘Robotic fingers, which are the key parts of robot hand, are divided into two main kinds： dexterous fingers and under-actuated fingers. Although dexterous fingers are agile, they are too expensive. Under-actuated fingers can grasp objects self-adaptively, which makes them easy to control and low cost, on the contrary, under-actuated function makes fingers feel hard to grasp things agilely enough and make many gestures. For the purpose of designing a new finger which can grasp things dexterously, perform many gestures and feel easy to control and maintain, a concept called ＂gesture-changeable under-actuated＂ （GCUA） function is put forward. The GCUA function combines the advantages of dexterous fingers and under-actuated fingers： a pre-bending function is embedded into the under-actuated finger. The GCUA finger can not only perform self-adaptive grasping function, but also actively bend the middle joint of the finger. On the basis of the concept, a GCUA finger with 2 joints is designed, which is realized by the coordination of screw-nut transmission mechanism, flexible drawstring constraint and pulley-belt under-actuated mechanism. Principle analyses of its grasping and the design optimization of the GCUA finger are given. An important problem of how to stably grasp an object which is easy to glide is discussed. The force analysis on gliding object in grasping process is introduced in detail. A GCUA finger with 3 joints is developed. Many experiments of grasping different objects by of the finger were carried out. The experimental results show that the GCUA finger can effectively realize functions of pre-bending and self-adaptive grasping, the grasping processes are stable. The GCUA finger excels under-actuated fingers in dexterity and gesture actions and it is easier to control and cheaper than dexterous hands, becomes the third kinds of finger.
基金supported by the National Natural Science Foundation of China(Grant Nos.91748118 and 12032015)the Program of Shanghai Key Laboratory of Spacecraft Mechanism+2 种基金the National Natural Science Foundation for Distinguished Young Scholars of China(Grant No.11625208)the Program of Shanghai Academic/Technology Research Leader(Grant No.19XD1421600)the National Postdoctoral Program for Innovative Talents(Grant No.BX20190201)。
文摘The application of soft pneumatic actuators is typically hindered by the low strength and slow response speed caused by their intrinsic material limitation and unstressed stable form.In this work,we present a design strategy for improving the performance and response speed for Pneu-Nets actuators by incorporating adjustable elastic components to form the elastic composite pneumatic actuator(ECPA).The elastic energy storage of the elastic component is implemented to enhance the capability and speed up the response of ECPA and pre-bend the actuator.Due to the design principle,the fully-flexible ECPA is easy to manufacture and regulate.Theoretical modeling and experiments are implemented to reveal the fast response characteristics and adjustable mechanical characteristics of ECPA.Experimental results show that the deflation response speed of ECPA is increased by at least 3.1 times with the action of elastic components,what is more,the stiffness of ECPA is increased by 22 times.Based on the ECPA,two kinds of locomotion robots including a running robot(runs at an average locomotion speed of 6.3 BL/s(body lengths,BL))and an underwater swimming robot(achieves an average speed of 1.1 BL/s)are designed.The fast-moving robots both demonstrate high-speed mobility because of the rapid response and high strength of ECPA.
