A fractional-N frequency synthesizer for 433/868MHz SRD applications is implemented in a 0.3μm CMOS process. A wide-band VCO and an AFC are used to cover the desired bands. A 3bit third order sigma-delta modulator is...A fractional-N frequency synthesizer for 433/868MHz SRD applications is implemented in a 0.3μm CMOS process. A wide-band VCO and an AFC are used to cover the desired bands. A 3bit third order sigma-delta modulator is adopted to reduce the out-band phase noise. The measurements show a VCO tuning range from 1.31 to 1.88GHz with AFC working correctly,an out-band phase noise of -139dBc/Hz at 3MHz offset frequency, and a fractional spur of less than - 60dBc. The chip area is 1.5mm × 1.2mm and the total current dissipation including LO buffers is 19mA from a single 3.0V supply voltage.展开更多
Due to the intense vibration durirLg launching and rigorous orbital temperature environment, the kinematic parameters of space robot may be largely deviated from their nominal parameters. The disparity will cause the ...Due to the intense vibration durirLg launching and rigorous orbital temperature environment, the kinematic parameters of space robot may be largely deviated from their nominal parameters. The disparity will cause the real pose （including position and orientation） of the end effector not to match the desired one, and further hinder the space robot from performing the scheduled mission. To improve pose accuracy of space robot, a new self-calibration method using the distance measurement provided by a laser-ranger fixed on the end-effector is proposed. A distance-measurement model of the space robot is built according to the distance from the starting point of the laser beam to the intersection point at the declining plane. Based on the model, the cost function about the pose error is derived. The kinematic calibration is transferred to a non-linear system optimization problem, which is solved by the improved differential evolution （DE） algoritlun. A six-degree of freedom （6-DOF） robot is used as a practical simulation example, and the simulation results show： 1） A significant improvement of pose accuracy of space robot can be obtained by distance measurement only; 2） Search efficiency is increased by improved DE; 3） More calibration configurations may make calibration results better.展开更多
文摘A fractional-N frequency synthesizer for 433/868MHz SRD applications is implemented in a 0.3μm CMOS process. A wide-band VCO and an AFC are used to cover the desired bands. A 3bit third order sigma-delta modulator is adopted to reduce the out-band phase noise. The measurements show a VCO tuning range from 1.31 to 1.88GHz with AFC working correctly,an out-band phase noise of -139dBc/Hz at 3MHz offset frequency, and a fractional spur of less than - 60dBc. The chip area is 1.5mm × 1.2mm and the total current dissipation including LO buffers is 19mA from a single 3.0V supply voltage.
基金Projects(60775049,60805033) supported by National Natural Science Foundation of ChinaProject(2007AA704317) supported by the National High Technology Research and Development Program of China
文摘Due to the intense vibration durirLg launching and rigorous orbital temperature environment, the kinematic parameters of space robot may be largely deviated from their nominal parameters. The disparity will cause the real pose （including position and orientation） of the end effector not to match the desired one, and further hinder the space robot from performing the scheduled mission. To improve pose accuracy of space robot, a new self-calibration method using the distance measurement provided by a laser-ranger fixed on the end-effector is proposed. A distance-measurement model of the space robot is built according to the distance from the starting point of the laser beam to the intersection point at the declining plane. Based on the model, the cost function about the pose error is derived. The kinematic calibration is transferred to a non-linear system optimization problem, which is solved by the improved differential evolution （DE） algoritlun. A six-degree of freedom （6-DOF） robot is used as a practical simulation example, and the simulation results show： 1） A significant improvement of pose accuracy of space robot can be obtained by distance measurement only; 2） Search efficiency is increased by improved DE; 3） More calibration configurations may make calibration results better.
