Abstract: High speed operation is a recurring target in design and application of robotic manipulators. Moreover, maximizing the
ratio between the weight of the payload and of the whole mechanism is a common objective. Therefore the use of a
lightweight robot is a good practice that can help to reach these goals. On the other hand, the use of lightweight and
therefore flexible manipulators requires the use of efficient control techniques and clever trajectory planning strategies
. For this reason, a large number of techniques have been proposed in literature to solve the problem of trajectory
planning and control of such mechanisms . Limiting our investigation only to the development of trajectory planning
alogrithms, both model-based  and model-free techniques have been proposed .
In this paper we deal with the model-based trajectory planning of flexible-link robots. A large number of techniques
have been developed for rigid-link robots, while the same problem is less frequently investigated for the case of manipulators
with flexible-links, i.e. when the flexibility is distributed along the links of the robot. At the same time, the aim
of this paper is to use the technique of desensitization to increase the robustness of the planned trajectory with respect
to parametric perturbation of the plant. In fact several authors have emphasized  that the optimal control techniques
which are commonly used in the case of model-based approaches, lead to a lack of robustness. This means that a trajectory
that is optimal in the nominal case, is far from the optimal solution if applied to a perturbed plant. This can happen quite
frequently, given the general difficulty of using (and tuning) accurate dynamic models of flexible-link mechanisms.
In this paper, a possible solution to this problem is proposed. The approach is based on the definition of a Two-Point
Boundary Value Problem (TP-BPV), which is augmented with the introduction of one or more sensitivity functions. A
similar approach has been used in some works by Singh , but its application is limited to linear plants. Here, a nonlinear
model of a single flexible-link mechanism, which has been validated in , is taken into account.