Human-Robot Co-Working is an active research domain in the field of robotics and control theory. Most of pioneering contributions addressing Co-Working interaction control problems has focused on PID based control. On the other hand, there are, in modern control theory, several tools allowing to design and tune arbitrarily complex servo-controllers. Non-Smooth optimization is one of recently developed tools that addresses the problem of tuning structured controllers according to H∞, H2, and pole placement specifications. In this paper, the problem of force amplification is transcribed into high level H∞ specifications and is solved using Non-Smooth optimization. The resulting controller is tested on an industrial robot and shows similar performances as the state of the art while respecting some extra robustness certificates. Therefore, thanks to the abstraction level of the proposed technique, it becomes possible to tune interaction controllers with high number of tunable parameters according to complex performance/robustness specifications.