Revised Modelling, parameterizing and validating the motion of a tadpole style cargo tricycle with real world experiments

In the past years, cargo bicycles in different configurations have gained popularity for many use cases. Their configurations differ substantially. Single-track cargo bicycles and their kinematics are linked closely to conventional bicycles. The kinematics of inverted tricycles, so-called tadpole trikes, are different. In this work, we model the motion for such a tadpole tricycle with articulated steering in order to predict the kinematic potential of such a vehicle. A single-track model for vehicle kinematics is implemented and compared to a planar model that incorporates a term for the lean (or roll) angle. To do so, the connection between steering and lean angle is calculated by the help of wheel flop. This is validated by inversing the modelling process and optimizing the geometrical approach function with the help of naturalistic cycling studies. The tricycle used for this study is measured experimentally in order to find the parameters for the model. It is then equipped with measuring devices and we present our instrumented tadpole cargo tricycle. By the help of it, we validate the two presented kinematic models for the motion of the tadpole tricycle with real world measuring data for given driving scenarios. These models are impinged with data from our experimental driving maneuvers. It is shown that our derived kinematic models hold reasonably well against the measurements for short term predictions during driving scenarios below the limits of driving dynamics. For the performed test scenarios, we compare the experimentally measured trajectory with the simulated ones and quantify the error. It is shown that a planar model that incorporates lean performs minimally better compared to a single-track model. We discuss model limitations as well as potential inaccuracies caused by the used measuring devices on our instrumented cargo tricycle. With the help of the kinematic models, motion prediction of tadpole cargo tricycles can be undertaken. The range for which the implemented planar models are considered to be valid is depicted by the range of forward speeds until the liftoff condition. For motion prediction, a single-track model is considered feasible, as the more complicated planar model with lean does not substantially outperform it. For maneuvers at the limits of driving dynamics, more sophisticated dynamic models are needed, as the simple kinematic models presented in this work are not sufficient for this kind of tasks.