Robust Concurrent Design of a 2-DOF Collaborative Robot (Cobot)

Uncertainties play a fundamental role in systems design, since the device behavior may be undesirable in the presence of unknown parameters. For devices interacting with humans, the force exerted by different operators represents a source of uncertainty, which under specific circumstances, could lead to undesired performance. This article proposes a robust concurrent design of a planar 2-DOF cobot modeled as a differential algebraic system and considers the force exerted by the human operator as the output of a PD controller. The robust concurrent design keeps the system performance as less sensitive as possible despite the different operators that interact with the device. Therefore, we establish the robust concurrent design as a multiobjective dynamic optimization problem, intended to minimize both the trajectory tracking error and its sensitivity with respect to uncertain parameters. The source of uncertainty comes from the force applied by the human operator while the independent variables are the inertial and kinematic parameters of the links in the kinematic chain, as well as the cobot controller gains. Experimental results show the effectiveness of the proposed design methodology.