Direct compensation of the spindle rotation error with an active hydrostatic journal bearing system

Spindle rotation accuracy is important in machining process. Indirect compensation of spindle rotation error has been widely adopted in the field of machining accuracy improvement. However, there are some limitations on indirect compensation, and a little research on direct compensation can be found. This article utilizes active lubrication technology to improve the spindle rotation accuracy. Hydrostatic journal bearing with control recesses and servo valve drove by piezoelectric ceramics are adopted to compose the compensation element. The simple control strategy PID is adopted to provide control signal for servo valve. Both simulation and experiment are designed and conducted. The results show that proposed bearing system has the ability to improve the spindle rotation accuracy.

Research on online calibration of lidar and camera for intelligent connected vehicles based on depth-edge matching

The practicality of online calibration algorithms in actual autonomous driving scenarios is enhanced by proposing an online calibration method for intelligent networked automotive lidar and camera based on depth-edge matching. The initial values of external parameters are estimated and calculated through hand-eye calibration. The solution of hand-eye calibration is optimized and accurate external parameters are obtained through data conversion. The CMA-ES algorithm is utilized to optimize the optimized parameters which are further compared with the conventional method based on edge matching. It is found that the provided frames of data, the external parameters can be appropriately improved by the method in this paper, and the algorithm congregates in about 1000 seconds. However, the conventional method cannot optimize the parameters correctly when there are only 2 frames of data. The rotation error of most results of this method is between 0.1° and 0.8°, and the translation error is between 0.02m and 0.06m. Compared with other representative algorithms of various methods, the errors in all aspects are more balanced and there is no outstanding error value.

Influence of tooth profile on rotation error of eccentric gearing satellite

In the article a cycloid internal engagement of gears that form an eccentric gearing, is considered. This engagement is investigated in point of insensitivity to assembly error. Only one type of assembly error – error of center distance i. e. eccentricity – is considered. It is expanded that workability of gearing with center distance error is provided on the assumption of decrease of diameter of roller that acts as central gear tooth. Roller diameter decrease and center distance error lead to breach of condition of conjugation of gears of eccentric gearing that in turn governs the output member rotation error. IThe output member and rotation transmission mechanism are not considered. Thus output member rotation error is equated to rotation error of eccentric gearing satellite. The influence of tooth profile on rotation error of eccentric gearing satellite is estimated when center distance error. On the base of matrix kinematic the methodology that takes in account the multiple-tooth contact is worked out. On basis of the developed methodology the research of influence of satellite tooth profiles formed on the base of shortened and extended epicycloids on rotation error is carried out. It is determined that in the eccentric gearing the use of satellite tooth profiles, formed on the base of extended epicycloid, makes it possible to decrease the rotation error. At that makes possible the operation of eccentric gearing in general manufacturing settings. Thus, the possibility of extending of eccentric gearing application fields to driving devices with higher requirements to overall sizes, mass, as well as cost, is come.