Rafael Fietzek

Observer validation and model based control of a two mass oscillator with backlash

In many technical systems, like for example automotive powertrains, the torque generated by the actuator is transmitted through an elastic shaft with backlash, which results in a system where the controlled variable is not collocated with the actuator. A model based pole placement control approach can be used to achieve satisfying closed loop dynamics. However for this approach the system states have to be known, but for cost reasons not every variable can be measured. Therefore a powertrain of an electric car is modeled as a two mass oscillator with backlash and a nonlinear observer is designed to estimate the system states in this paper. The comparison of simulated and measured data is used to validate the performance of the observer depending on the number of measured variables.

Vehicle Mass Estimation from CAN Data and Drivetrain Torque Observer

A method for estimating the vehicle mass in real time is presented. Traditional mass estimation methods suffer due a lack of knowledge of the vehicle parameters, the road surface conditions and most importantly the effect of the vehicle transmission. To resolve these issues, a method independent of a vehicle model is utilized in conjunction with a drivetrain output torque observer to obtain the estimate of the vehicle mass. Simulations and experimental track tests indicate that the method is able to accurately estimate the vehicle mass with a relatively fast rate of convergence compared to traditional methods.