The static friction
coefficient ([[my].sub.s]) of the beans was determined by the method outlined by Kaliniewicz et al.
Consequently, the static friction
torque for rotation is remarkably reduced to 10.5 gm (0.103 Nm), which approaches zero.
Employing generalised matrix inverses (GI), an intuitive and effective computation method of the static friction
forces is deduced, considering Gauss' least constraint principle.
Due to this stochastic nature, at each time, different control signal values are needed to overcome static friction
in the same specific position, and different values of minimum speed are required so that the valve does not grip during opening or closing procedure, being not compatible with traditional model-based controllers.
The reason for introducing [[epsilon].sub.f] in (5) is because the classical Coulomb friction model only defines the maximum static friction
for the stick state; the actual static friction
force can take on any value in the interval between zero and [f.sub.[sigma]][[mu].sub.s], depending on the magnitude of the total nonfrictional external force.
As shown in Figure 4, the motion of a curved surface slider is characterized by at least three phases, which corresponds to different friction factors: [[mu].sub.0] is the static friction
relative to the onset of motion; [[mu].sub.dyn] = [mu] is the dynamic friction during the sliding with velocity similar to the design one; [[mu].sub.1] is the friction factor corresponding to the change of velocity sign.
8, the net static friction
with the presence of magnetic flux passing through steel plate and platform is given by:
When [F.sup.(1).sub.s] cannot overcome the static friction
force [F.sup.(1).sub.f] (i.e., [absolute value of [F.sup.(1).sub.s]] [less than or equal to] [absolute value of [F.sup.(1).sub.f]]), mass [m.sub.1] does not have any relative motion to the belt, that is,
Halperin, "Experimental investigation of the elastic-plastic contact area and static friction
of a sphere on flat," Journal of Tribology, vol.
Moreover, the analytic conditions for stick and nonstick motions are developed, and the influence of the maximum static friction
torque and the driving torque on the stick motion is predicted numerically.