This paper presents a macro-micro dual stage using hybrid actuators composed of voice coil motor (VCM) and piezoelectric actuator (PZT). Connecting coarse (driven by voice coil motor) and fine (actuated by the piezoel...
详细信息
ISBN:
(纸本)9781479913329
This paper presents a macro-micro dual stage using hybrid actuators composed of voice coil motor (VCM) and piezoelectric actuator (PZT). Connecting coarse (driven by voice coil motor) and fine (actuated by the piezoelectric), in series, to achieve a large travel range and high precision positioning. In the structure of redundant actuation, the micro stage is applied to compensate the error generated by the macro stage. The compensating method of point-to-point (PTP) positioning is divided into two types: compensation before steady state (macro/micro single input dual output) and compensation before steady state (macro/micro dual input dual output). A corresponding driving process is described in each type. In the driving process, the interference behavior between macro stage and micro stage is considered and the dynamic coupling model established. In the process of control analysis, because of the saturation of micro stage, switching control plays an important role in realizing precision positioning. Mode switching control is achieved by using switching function according to the two types of positioning way. Finally, step response shows that the positioning accuracy of dual stage is higher than single macro stage, and also can realize nano-positioning.
Stable and fast switching between displacement and pressure will directly affect precision and velocity of automated equipment. Switching control between displacement and pressure, which is based on the velocity dampi...
详细信息
Traditionally, based on the pseudo rigid body model method, the ideal stiffness of double parallel four-bar mechanism is obtained by virtual work principle while support arm bar is regard as a rigid rod. However, a te...
详细信息
ISBN:
(纸本)9781479910267
Traditionally, based on the pseudo rigid body model method, the ideal stiffness of double parallel four-bar mechanism is obtained by virtual work principle while support arm bar is regard as a rigid rod. However, a terrible error between ideal and real stiffness will be caused in practice as a result of the bending deformation of support arm bar. Therefore, it is urgent to analyze the error of stiffness in double parallel four-bar mechanism and to explore the condition in which the support arm bar could be equivalent to rigid rod. In the paper, an accurate expression of stiffness in the double parallel four-bar mechanism is derived by integral method while the support arm bar is studied as a variable cross section beam through force analysis and deformation analysis. The error between stiffness derived from virtual work principle and integral method is obtained, and whose changing trend with the structural parameters of the right-angle flexure hinge and the support arm bar is analyzed. The result demonstrates that the error is less than 1% when the thickness ratio is larger than 6 and the length ratio is between 6 and 25, that is, the support arm bar can be equivalent to rigid rod, and whose bend deformation can be neglected.
This paper presents a new type of intelligent ultrasonic power supply based on DSP and DDS, and then designed a debridement transducer. The ultrasonic power supply consist of TMS320F2812, DDS waveform generating circu...
详细信息
ISBN:
(纸本)9781479927456
This paper presents a new type of intelligent ultrasonic power supply based on DSP and DDS, and then designed a debridement transducer. The ultrasonic power supply consist of TMS320F2812, DDS waveform generating circuit, Full-bridge inverter circuit, signal processing circuit and so on. In order to achieve frequency automatic tracking with the characteristics of high precision and fast speed, it adopted the control strategy of Integra separation PI algorithm and variable step size. Ultrasonic transducer is mainly composed of quarter wave oscillator and second order of the amplitude. Experiments show that both of the hardware and the software achieved the expect function, the ultrasonic power can achieve high precision frequency automatic tracking. Consequence, the results proved the designed method was feasible.
Connection frame has been a key module in a macro-micro platform. The error of connection frame deformation must be taken into account for nano-positioning motion in working process. While working, the nano-positionin...
详细信息
ISBN:
(纸本)9781479956234
Connection frame has been a key module in a macro-micro platform. The error of connection frame deformation must be taken into account for nano-positioning motion in working process. While working, the nano-positioning motion is affected by the two major deformation error sources: magnetic force and thermal structural coupling effects. These error models were built by response surface method. Each experiment result can be obtained by calculation of finite element method. Their input variables of orthogonal experiment design were imported to the commercial software ANSYS to calculate and obtain output. The response surface model was built by the input and output data. Based on these models, change trends of deformation errors with design parameters can be revealed. And an optimal model of total deformations errors would be built. Finally, the minimum error of connection frame deformation considering magnetic force and thermal structural coupling effect was calculated by genetic algorithm. The optimal solutions were obtained when the total error iterate to 15 times as follows, D=32mm, L1=80mm, R=64mm. The improvement of deformation error considering magnetic force, thermal-structural coupling force and high acceleration is 86.48%, 0.26%, 26.85% These results can provide a more accurate prediction of error analysis in more widely used cases and also offer a theoretical support for improving nano-positioning accuracy of macro-micro platform.
Inverse solution of five-axis machine tool is that given the excepted point of tool-tip and the excepted vector of tool-axis to solve the G codes of five axes, it is the key step of five-axis machining. Based on the e...
详细信息
Stable and fast switching between displacement and pressure will directly affect precision and velocity of automated equipment. Switching control between displacement and pressure, which is based on the velocity dampi...
详细信息
ISBN:
(纸本)9781479913329
Stable and fast switching between displacement and pressure will directly affect precision and velocity of automated equipment. Switching control between displacement and pressure, which is based on the velocity damping, is proposed for motion switching of automated equipment. At first, the control models were established by analyzing displacement control and pressure control. To solve the shortage of direct switching between displacement and pressure, switching control based on the velocity damping is presented. The effectiveness of this method is verified by using piezoelectric sensor in experiment. Compared to direct switching control, the proposed switching control becomes more accurate and faster. The measurement data shows that the maximal impact force of control system is 0.4N and the amplitude of forces of fluctuations are within the range of ±0.03N.
暂无评论