Measurement Of The Clearance Of Intelligent Ball Joint And Calibration Promotion Technology

Precision ball hinge is a mechanical joint with three degree of freedom,which is widely applied in robots,parallel mechanisms,automobiles and medical devices on account of its flexible movement,compact structure,load capacity.But its rotation orientation and clearance error can not be determined.If the rotation angle and clearance of the ball hinge can be detected accurately in real time,it will be helpful to improve the accuracy of subsequent mechanical control.In this paper,an embedded intelligent ball hinge that can detect the rotation angle and moving clearance based on our previous research results is proposed.In view of the low precision of the intelligent ball hinge and the problem that the clearance cannot be acquired automatically,main works and study of this article are as follows: The relationship model of the ball hinge between the clearance and the eccentric at three axis of the ball head is established.A point capacitance model for measuring the clearance is constructed;Based on the point capacitance model,an experimental platform using eddy current sensor has been finished.Controlled by the pneumatic device,the clearance value of the ball hinge is measured by the inductive sensor.And finally the eccentricities of three axis in different angles and axial loads is calculated;A new type of error evaluation device for ball hinge was developed,which is benefit to the error assessment accuracy of the ball hinge;Based on the equivalent magnetic charge model and the space rotation model,a new detection device and its method on account of magnetic effect is proposed.Simple measurement for spatial position without guide and scale is achieved.The experimental results of clearance measurement based on eddy current sensor shows that the method can realize eccentricity components measurement along three directions in different rotation angles and different force.The experimental data indicate that the influence of rotation angle change on ball hinge eccentricity is greater than that of load force.The resolution of the clearance measurement device can reach 0.05μm,and the reliability of eddy current sensor method is higher than that of inductive sensor.The device is applicable to clearance measurement of spherical hinge,universal joints and so on.From data analysis of the new calibration device,within ±5°of angle α and ±20° of β,the average error of α is 3.4’,the average error of β is 9.6’.Compared with previous results,the accuracy of angle measurement has been improved a lot.