This paper presents a novel approach to optimize the design of planar mechanisms with revolute joints
for function-generation or path synthesis. The proposed method is based on the use of an extensible-link
mechanism model whose strain energy is minimized to find the optimal rigid design. This enables us to
get rid of assembling constraints and the use of natural coordinates makes the objective function simpler.
The optimization strategy is divided into two stages: the first one relies on multiple partial optimizations
and provides hot starting point for the second stage which involves all the variables and all the energy
contributions. The question of finding the global optimum is reviewed. Instead, a simple algorithm is
proposed to explore the design space and to find several local optima among which the designer may choose
the best one taking other criteria into account (e.g. stiffness, collision, size,. . . ). Two applications are
presented to illustrate the whole process
