Comment on "Minimum Energy-Loss Guidance for Aeroassisted Orbital Plane Change"

Abstract We study a recently proposed compound two degrees of freedom planar leg mechanism consisting of a four-bar linkage and a pantograph. In this mechanism, one degree of freedom is used for normal walking to provide an ovoid path which emulates that of humans while the other is used only when necessary to walk over obstacles. Potential advantages of such a compound mechanism are fast locomotion, minimal energy loss, simplicity in controller design, and slenderness of the leg. To exploit these to the fullest, a multiobjective optimization-based design problem formulation is proposed with the following four design objectives: (i) minimum leg height, (ii) minimum of the maximum joint forces, (iii) minimum leg mass, and (iv) minimum energy loss for a walking cycle. In addition, this problem formulation takes into account a combination of mechanism requirements and structural requirements. Several tradeoff solutions are obtained using the Consol-Optcad interactive optimization-based design package.

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Energy Efficient Cam-Follower Systems

Journal of Mechanisms Transmissions and Automation in Design ◽

10.1115/1.3258534 ◽

1983 ◽

Vol 105 (4) ◽

pp. 681-685 ◽

Cited By ~ 11

Author(s):

F. Freudenstein ◽

M. Mayourian ◽

E. R. Maki

Keyword(s):

Energy Efficiency ◽

Energy Loss ◽

Energy Efficient ◽

Energy Savings ◽

Functional Dependence ◽

Minimum Energy ◽

Optimization Strategy ◽

Cam Follower ◽

Return Spring ◽

Rating Factor

The energy loss in cam-follower systems due to friction between moving parts can be a significant contributor to the power loss in machinery. Considering the total number of cam-operated machines in manufacturing and other operations, the energy savings obtainable by improving the efficiency of the average cam-follower system by even a small percentage would be significant. In this investigation a new rating factor—an energy-loss coefficient proportional to the energy loss at the cam-follower interface—has been defined and evaluated. The rating factor relates to energy efficiency in a manner analogous to the way in which the well-known rating factors for velocity, acceleration, and shock relate to the kinematic characteristics of the cam-follower system. Two cam-follower configurations have been considered: 1) a follower motion governed by both cam and return spring, and 2) a follower positively driven by the cam. In both cases it was found that cam curves with identical rise and rise times can differ substantially in energy efficiency thereby demonstrating the significance of an energy-optimization strategy in the design of cam-follower systems. The nature of the functional dependence of the energy loss on system parameters has been identified and a minimum energy-loss limit established.

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