Effect of lubrication on impact drive mechanism

Piezoelectric Inertia Motors—A Critical Review of History, Concepts, Design, Applications, and Perspectives

“…This differentiation seems justified, as only moving actuator inertia motors can use an "impact" on the motor to generate additional displacement, but this explanation is rarely found in literature [111] (p. 37f). The use of the different terms rather seems to have historical reasons: "impact drive (mechanism)" is used for moving actuator motors, and mostly by authors whose works are to different extents based on the early works of Higuchi et al [35,110] on this type of motor; e.g., in [64,70,[113][114][115][116]. The derived term "smooth impact drive mechanism" is used for fixed actuator motors by authors who directly or indirectly refer to the works of Okamoto, Yoshida et al [26,117,118] (e.g., in [25,95,119,120]).…”

“…The literature contains some examples of inertia motors with quickly changing normal force, realised by piezoelectric actuators [144], electromagnets [113,145], electrostatic forces [43,140,146], or inertial forces [147,148]. In all these motors, the normal force is increased in the propulsion phase, during which a large tangential force shall be transmitted, and/or decreased in the retraction phase, during which a low friction force is desired.…”

“…Some authors have experimentally compared different friction couples in inertia motors (e.g., [41,84,113,[173][174][175]). Bergander [111] (pp.…”

“…The fact that lubrication reduced the step size of their motor should not be seen as proof of a general disutility of lubrication in inertia motors, as two motors with different friction couples have different optimal control signals. In fact, the experiments by Furutani et al [113] with steel couples and different lubrication fluids indicate that lubrication can be beneficial for different reasons. It increases the uniformity of the contact, resulting in less variation of the step size and less movement of the slider perpendicular to the contact [113].…”

Modeling and control of piezoelectric inertia–friction actuators: review and future research directions

“…It is clear that the result from these works suggests that the Coulomb model for friction in PIFAs is not adequate. Other works such as Furutani et al (1998), Chang and Li (1999), and Jiang et al (2000), which also used the Coulomb model for friction, did not discuss the adequacy of the Coulomb model for frictional contact in PIFAs.…”