Modeling and analysis of spherical micromanipulator dynamics based on the stick-slip effect

A spherical micromanipulator is a micro robotic system largely applied to the micro/nano precision positioning, which is composed of a seat, a micro-ball and 3 piezoelectric tubes with ruby balls on the top. Rotations with 3-DOFs of the micro-ball are achieved with the relative displacements brought by the frictions between the ruby balls and the micro-ball. The stick-slip effect exists in this friction movement, whose nonlinear characteristic leads to the serious complication of the system dynamics. A dynamic model of the micromanipulator with stick-slip characteristic is established under the condition of simplifying spherical higher pair joints. Based on the dynamic friction model, a method of numerical analysis is used to value the effects played by several parameters. The dynamic model is demonstrated by simulations. The rotation experiment is also done, and the validity of the micromanipulator dynamic model is further proved by the results.