Stabilisation and manoeuvre of electrically powered pedestrian controlled uniaxial vehicles for goods transport

Uniaxial vehicles for goods transport such as hand trucks are popular with many transport tasks. They offer intuitive manoeuvrability with little space requirements. The disadvantage of this class of pedestrian controlled means of transportation is the need for the user to apply force for stabilisation and propulsion. To eliminate this disadvantage a solution approach is to equip the vehicle with a controlled drive system providing force for both balancing and propulsion. To make possible stabilisation of a uniaxial vehicle for goods transport without need for external support the frame´s pitch angle must be adapted with every change of load, which is a fundamental difference to uniaxial vehicles without payload or for passenger transportation. To make possible intuitive and convenient pedestrian controlled manoeuvre even with high payload the controller must set translational and rotational speed based on low interaction forces applied by the user going along. To allow for cheap production we developed a balance and manoeuvre controller not requiring sensor information of both load´s absolute weight and user interaction forces. Main components of the concept are a balance controller including a Kalman state estimator for identification of frame´s and load´s combined centre of gravity´s pitch angle, a manoeuvre controller based on state space control and a sophisticated program sequence switching automatically between operating modes for reload and manoeuvre. The control concept was designed and implemented using our new uniaxial vehicle system for urban goods transport. This vehicle is the first electrically powered hand truck that both balances adaptive to changing payload and allows for pedestrian controlled manoeuvre without need to operate control levers for setting speed or steering angle. The experimental results presented in this paper show the correct operation of the approach.