Fraunhofer-Institut für Produktionsanlagen und Konstruktionstechnik IPK

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Adaptive backstepping controller with Kalman state estimator for stabilisation and manoeuvre of pedestrian controlled uniaxial transport vehicles

2015 , Brüning, M. , Thiele, Gregor , Schönewolf, W. , Krüger, J.

Pedestrian controlled uniaxial vehicles for goods transport such as hand trucks offer intuitive manoeuvrability with little space requirements. The disadvantage of this class of statically underdetermined vehicles is the need for the user to apply force for both stabilisation and propulsion. Removing this disadvantage is the key to enable their use for convenient transportation of heavy goods over long distances. For this our solution approach is to equip the vehicle with controlled drives providing force for both balancing and propulsion. Different to uniaxial vehicles without payload or for passenger transportation controller's adaptation to kinematic and dynamic parameters is required here after every reload. The frame's pitch angle must be adapted with every change of load whereby the COG's position is not measurable with acceptable effort. Dynamic parameters vary in a wide range. We applied an adaptive controller based on backstepping combined with Kalman state estimation for stable balancing with adaptation to changed payload without need for external support from the user. The manoeuvre concept based on low interaction forces applied from the user to the vehicle frame is taking advantage of the underconstrained dynamics of the vehicle, and offers similar driving behaviour to the user with different load situations. Operating control levers for setting speed is not required. To allow for cheap production a design goal was not requiring sensor information of both load's absolute weight and user interaction forces. The adaptive control and state estimation concept was simulated based on the kinematic and dynamic model of our new uniaxial vehicle system designed for urban parcel distribution on foot. Simulation results show the correct operation of the approach.

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

2014 , Brüning, M. , Schönewolf, W. , Krüger, J.

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.

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