Identification and Inverse Torque Control of Hydrodynamic Dynamometers

Hydrodynamic dynamometers are employed in internal combustion engine (ICE) test benches for the entire range of ICEs, from cart engines to large ship engines. They are inexpensive and characterized by a relatively small moment of inertia. Although nonlinearities and the absence of accurate models make controlling these dynamometers a difficult task, they are currently used almost exclusively for stationary measurements. To overcome this limitation, this paper proposes an inverse torque control based on a Wiener approximation whose parameterization is strongly simplified by choosing a suitable set of basis functions for the nonlinear map. As inverting this nonlinear map would be computationally demanding, it is replaced with a dynamic inversion which - together with the actuator redundancy - allows additional optimality criteria to be incorporated. The performance of the proposed control law is validated by measurements on a test bench and shows significant improvement compared with classical implementations.