Research On Dynamic Modeling And Control Strategy For Hybrid Tracked Bulldozer

Bulldozers with traditional mechanical structure have low energy utilization rate, poor emissions performance, and high fuel consumption because of its poor load adaptability when confronted with complex working conditions with load changing frequently. Hybrid technology is the best way to improve the bulldozer’s fuel economy under the existing technology conditions. Dynamic Modeling and control strategy for hybrid tracked bulldozer are researched in this paper to improve its fuel economy in the premise of ensuring its dynamic characteristics.The analysis of terra-mechanics of tracked bulldozer provides the theoretical basis for dynamic modeling. Control strategy and its optimization for the hybrid tracked bulldozer are researched based on the dynamic modeling. The main research work is as follows:1) Terra-mechanics of tracked bulldozer is researched by discussing mechanical problems of the interaction between the walk device, working parts and the ground. Meanwhile, Terra-mechanics can provide the theoretical basis for travel dynamics modeling.2) A control-oriented travel dynamics model is established. The dynamic simulation of straight driving, steering and working condition are performed to verify the validity of the travel dynamics model. Then, the parameters matching and type selection are performed for the key components of the hybrid tracked bulldozer.3) The entire power train dynamic model for the hybrid tracked bulldozer is established. Based on analyzing of the Terra-mechanics and travel dynamics model, a control-oriented simulation model of the hybrid tracked bulldozer is established. This model includes the engine-generator, ultracapacitor, drive motor system, driveline and bulldozer travel dynamics model. The model can not only reflect the changes of the control strategy parameters such as the engine-generator set operating speed points, ultracapacitor’s SOC and fuel consumption, but also reveal the energy control and distribution process between engine-generator set and ultracapacitor. Comparison of the simulation results and the real vehicle experimental data is performed to verify the accuracy of the simulation model of the hybrid tracked bulldozer.4) Engine control strategy and energy management strategies are researched based on the working characteristics of the bulldozer. Off-line simulation is performed based on the bulldozer typical and integrated working condition to verify the effectiveness of these control strategy. The bench test experiment for the hybrid tracked bulldozer is performed to verify the rationality and feasibility of the control strategy further more.5) In order to further improve the fuel economy, control strategy parameters for the hybrid tracked bulldozer are optimized. The optimization model is established with optimum fuel consumption as the objective function, and engine speed and ultracapacitor’s SOC as the design variables. Then parameters optimization of the control strategy is performed by using the adaptive genetic algorithm. The results show that this method is effective which is used for control strategy optimization can improve the fuel economy of the hybrid tracked bulldozer, and it also can greatly reduce the control parameters of the real vehicle calibration time.Hybrid tracked bulldozer using the load power following control strategy can improve the fuel economy effectively and the control strategy parameters optimization by using the self-adaptive genetic algorithm can reduce the fuel consumption further more.