The Leading-Edge(LE)serrations on owls'wings are known to be responsible for silent ***,this design has rarely been applied to reduce the noise of rotational rotor propellers and the morphologies of the existing s...
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The Leading-Edge(LE)serrations on owls'wings are known to be responsible for silent ***,this design has rarely been applied to reduce the noise of rotational rotor propellers and the morphologies of the existing serration designs are ***,we present a comparative study ofLE serrations with different morphologies in terms of the effectiveness in suppressing noise and promoting thrust *** performances of biomimetic propellers are investigated by Computational Fluid Dynamics(CFD)simulations and rotation *** simulation results reveal that LE serrations could reduce velocity fluctuations and change the lamina-turbulent transition and turbulence distribution on the suction surface of propeller,but the morphology of the serrations influences its *** testing results indicate that the sawtooth propeller has the best performance on noise reduction(on average 2.43 dB and in maximum 4.18 dB)and simultaneously enhancing the thrust forces(3.53%).The largest practical noise reductions(4.73 dB and 3.79 rdB)using the sawtooth propeller are observed when the quad-rotor Unmanned-Aerial Vehicle(UAV)is hovering at heights of 5 m and 8 m,*** results indicate the robustness and usefulness of owl-inspired biomimetic serration devices for aero-acoustic control and aerodynamic performance promotion on propeller *** finding is expected to con^bute to suppressing the sound of propeller and the rotor-based aircraft.
We performed the fabrication of the lens array mould with embossing type surface by using a fast tool servo. To overcome the nonlinear hysteresis characteristics of the piezoelectric actuator in fast tool servo, the p...
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ISBN:
(纸本)9780995775107
We performed the fabrication of the lens array mould with embossing type surface by using a fast tool servo. To overcome the nonlinear hysteresis characteristics of the piezoelectric actuator in fast tool servo, the proportional integral controller with feedforward compensator was used. Also, to meet the large optical sag required in most of commercial optical devices, the fast tool servo with large displacement up to hundreds of micro meter has been integrated into the diamond turning machines. To synchronize the fast tool servo and the diamond turning machine, the precision encoder signal from the CNC was read and used to update the control input to the high voltage amplifier for the piezoelectric actuator. The machined result shows that the proposed controller and tool servo can be successfully integrated into the machine and can fabricate the complex optical surfaces with embossing shape.
We describe a two-dimensional piezoelectric laser scanner designed and tested to obtain the large steering angle of 1 degree and fast response characteristics with 200 Hz. To overcome the relatively small expansion ca...
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We describe a two-dimensional piezoelectric laser scanner designed and tested to obtain the large steering angle of 1 degree and fast response characteristics with 200 Hz. To overcome the relatively small expansion capability of piezoelectric actuator, the displacement amplification mechanisms are employed to magnify the end tip of the lever which is connected to the 0.5" aluminum mirror. For fast response characteristics, several shapes of the displacement amplification mechanisms are proposed and their natural frequencies calculated by using finite element analysis technique. As a result of performance testing of hinge mechanisms by exciting the actuator, the resolution of the proposed piezoelectric scanner shows the excellent capability in beam steering. Also, the actual machining test of the proposed laser scanner in the burning paper are performed to show that it is capable of steering the laser beam in 1 degree and with frequency of 200 Hz.
This research designs a robot gripper for a rapid service robot. For a service robot that moves rapidly, a robot gripper must be lightweight and must have the ability to grasp objects of any size or shape stably. In a...
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This research designs a robot gripper for a rapid service robot. For a service robot that moves rapidly, a robot gripper must be lightweight and must have the ability to grasp objects of any size or shape stably. In addition, sufficient gripping force, a low cost, and a friendly shape are necessary. To satisfy the above requirements, this research designs a new robot gripper. We use a four-bar linkage underactuated system for shape adaptability and to reduce the weight. In a simulation, the four-bar linkage is designed to eliminate the rollback ejection phenomenon while also maximizing the utilization of a parallel grasping. While other studies place emphasis on preventing rollback ejection phenomenon, in this research we stress the maximum utilization of both parallel and power grasping using a compliance jaw and a double four-bar linkage design. With the parallel four-bar linkage system, the gripper can perform both parallel grasping and power grasping, allowing it to grip a diverse range of objects. Moreover, the compliant jaw enhances the stability of its grasp, and its worm gear enables the gripper grasp to be stable while also reducing the gripper's weight. With a force sensor, it can manage sensitive force control. In this way, we designed a robot gripper suitable for rapid service robots.
Currently,two rotations and one translation(2R1T)three-degree-of-freedom(DOF)parallel mechanisms(PMs)are widely applied in five-DOF hybrid machining ***,there is a lack of an effective method to evaluate the configura...
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Currently,two rotations and one translation(2R1T)three-degree-of-freedom(DOF)parallel mechanisms(PMs)are widely applied in five-DOF hybrid machining ***,there is a lack of an effective method to evaluate the configuration stiffness of mechanisms during the mechanism design *** is a challenge to select appropriate 2R1T PMs with excellent stiffness performance during the design *** the operational status of 2R1T PMs,the bending and torsional stiffness are considered as indices to evaluate PMs'configuration ***,a specific method is proposed to calculate these stiffness ***,the various types of structural and driving stiffness for each branch are assessed and their specific values ***,a rigid-flexible coupled force model for the over-constrained 2R1T PM is established,and the proposed evaluation method is used to analyze the configuration stiffness of the five 2R1T PMs in the entire ***,the driving force and constraint force of each branch in the whole working space are calculated to further elucidate the stiffness evaluating results by using the proposed method *** obtained results demonstrate that the bending and torsional stiffness of the 2RPU/UPR/RPR mechanism along the x and y-directions are larger than the other four mechanisms.
作者:
陈学东田文罡李小清渡边桂吾School of Mechanical Science and Engineering
Huazhong University of Science and Technology Wuhan 430074 China Dept. of Advanced Systems Control Engineering
Saga University Japanhe robot consists of a quadruped mechanism and two active dual-wheel casters possesses the advantages of wheeled and legged mechanism and can quickly move on the relatively plane ground with the wheeled mechanism and can walk on the extremely uneven terrain with the legged mechanism. The effectiveness of the motion design of the hybrid robot is iHustrated by simulation results.
The robot consists of a quadruped mechanism and two active dual-wheel casters possesses the advantages of wheeled and legged mechanism, and can quickly move on the relatively plane ground with the wheeled mechanism, a...
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The robot consists of a quadruped mechanism and two active dual-wheel casters possesses the advantages of wheeled and legged mechanism, and can quickly move on the relatively plane ground with the wheeled mechanism, and can walk on the extremely uneven terrain with the legged mechanism. The effectiveness of the motion design of the hybrid robot is iHustrated by simulation results.
Human emotion recognition is an important factor for social robots. In previous research, emotion recognizers with many modalities have been studied, but there are several problems that make recognition rates lower wh...
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Laser-arc hybrid welding is an attractive tool that has high potential in welding lightweight structure. The welding quality is improved by deep penetration with gap-bridging ability. This study examines the effective...
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ISBN:
(纸本)0912035757
Laser-arc hybrid welding is an attractive tool that has high potential in welding lightweight structure. The welding quality is improved by deep penetration with gap-bridging ability. This study examines the effectiveness an arc leading welding process through plasma phenomenon, melting efficiency and gap bridging ability experiment in melting pool. We apply hybrid welding using sheet aluminum welding to a vehicle body. We use 3KW cw Nd:YAG laser and 350A class MIG welding machine as an experiment device, high speed camera for melting phenomenon observation in melting pool and welding current measurement device for arc state observation.
Concerns a research and development project of advanced robot technology in Japan, finished in FY 1990. This project aimed to develop robots which could carry out inspection, maintenance, rescue operations or others i...
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Concerns a research and development project of advanced robot technology in Japan, finished in FY 1990. This project aimed to develop robots which could carry out inspection, maintenance, rescue operations or others in the field of nuclear power, subsea and disaster fighting. The various elementary technologies have been developed and the conceptual designs of total systems of the robots have been made taking those results into consideration. This paper describes the total system of the advanced subsea robot which supports the offshore oil exploitation and the verification experiment by the experimental robot which was carried out in December 1990.< >
Educational/entertainment robots are usually designed to perform various gesture motions for nonverbal communication or interaction with humans[1]. This paper proposed a robot motion programming methodology by applyin...
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Educational/entertainment robots are usually designed to perform various gesture motions for nonverbal communication or interaction with humans[1]. This paper proposed a robot motion programming methodology by applying three-level robot motion hierarchical structure and a gesture variation method that can easily apply emotional attributes (Joy, Normal or Sad) to a robot's gesture. Experiments and evaluation tests are conducted with a graphical robot motion simulator and a real robot named Engkey, which is developed to carry out several tasks for interactive English education in elementary school or interactive games for elderly people.
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