Development of look-ahead controller concepts for a wheel loader application
This paper presents two conceptual methods, based on dynamic programming, for one-step look-ahead control of a continuously variable transmission (CVT) in a wheel loader. The first method developed, designated Stochastic Dynamic Programming or SDP, uses a statistical load prediction and stochastic dynamic programming for minimizing fuel use. The second method developed, designated Free-Time Dynamic Programming or FTDP, has vehicle speed as a state and introduces a fixed 0:1s delay in the bucket controls in a combined minimization of fuel and time.
The methods are evaluated using a set of 34 measured loading cycles, used in a ’leave one out’ manner. The evaluation shows that the SDP method requires about 1/10th of the computational effort of FTDP and has a more transparent impact of differences in the cycle prediction. The FTDP method, on the other hand, shows a 10% lower fuel consumption, which is close to the actual optimum, at the same cycle times, and is able to complete a much larger part of the evaluation cycles.
Tomas Nilsson, Anders Fröberg and Jan Åslund
Oil & Gas Science and Technology - Rev. IFP,
2015
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