Performances and Shapes of Acceleration-deceleration Curve of Kinematical Linkages

Abstract

The transient duty has a very important role within the kinematical linkages of the numerical control machine tools and industrial robots. The acceleration and deceleration of the movable element of the kinematical linkage participates directly to achieving the positioning accuracy and to the path error. This work presents the main shapes of the acceleration- deceleration curve of the kinematical linkage, as well as their performances. Shapes of the acceleration-deceleration curve are presented for positioning linkages as well as for contouring linkages. The extent of influence upon the contour error in case of the linear and exponential acceleration-deceleration of kinematical linkage is also presented. The works is also giving recommendations on the way of choosing the type of curve being used in case of various transient processes, by the machine tool builders, with a view to obtaining high dynamical performances. In general, the recommendations are considering the inertia of the mobile element and the imposed path error. By knowing the acceleration shape, the machine tool designer and builder can know, even from the design stage, the area of the transient duty where the acceleration is maximal. The maximum acceleration imposes the rate of the impulsion torque of the drive servomotor based on which the kinematical linkage is sized, in terms of its components.