Using the Equal-Power-Based MCE to Transform Driving Cycles With Road Grade for Testing Heavy-Duty Vehicle Fuel Consumption on Dynamometer

Chassis dynamometer testing based on representative driving cycles is commonly performed in the evaluation of the fuel economy of heavy-duty vehicles. However, the requirement for a zero or fixed grade when using a traditional chassis dynamometer results in the inaccurate testing of the fuel economy of a vehicle to be driven on hilly roads. Against this background and considering that the engine operation and driving conditions should remain consistent, this study proposes an equal-power-based Markov chain evolution method whereby multi-parameter driving cycles with a time-varying road grade are transformed into desired driving cycles of zero grade. Adopting the condition of equal power before and after transformation, the driving cycles with a non-zero road grade are transformed into possible zero-grade driving cycles as the feasible cycle region. The Markov chain evolution is used to finally obtain the desired driving cycles from the feasible region. An analysis using real-world vehicle driving data reveals that the desired driving cycle obtained using the proposed method is similar to that in the original driving database. The engine distribution and driving characteristics of the desired driving cycle are highly consistent with those in the original driving database, with the correlation indices being as high as 90%, which verifies the credibility of the desired driving cycle. Additionally, simulation shows that the relative deviation of the fuel consumption per 100 km obtained using the proposed method remains within 10%, indicating the effectiveness of the proposed method. The proposed method is thus superior to the expected driving cycle transformation based on the equal-power method.