| The off-road multi-axis vehicles,such as missile launch vehicles,radar-carrying vehicles,and military/civilian off-road vehicles,have a wide range of driving requirements such as crossing obstacles and rocky,which impose urgent requirements on the control of body posture and wheel-axle loads.Multi-axle vehicles are affected by the complex deformation and load-bearing coupling relationship in their systems,and although the adjustments solved based on the rigid body coordinate transformation model can theoretically achieve body posture adjustment on good roads,they cannot meet the non-road environment high-performance attitude control;at the same time,the wheel load can only be controlled by feedback,and there are problems such as induced posture disturbance,uneven wheel load distribution,and even "false leg " and overload.In response to the above problems,this paper carries out a study on the coupled control of body height-posture and wheel load distribution for off-road multi-axle vehicles.The main work of the full paper is as follows:(1)The basic theoretical study of coupled control of body height-posture and wheel load distribution.Firstly,a simplified model of the multi-axle vehicle is characterized in terms of mechanical properties,and a control equation for the coupling between body height-posture and wheel load is established.Then,based on this equation,the body height-posture and wheel load distribution control concept relying on the forward and reverse control equation is proposed,and the main body height-posture and wheel load distribution control strategy under a typical non-road environment is constructed.The theory can realize the active control of vehicle height and posture,and at the same time,the synchronous control of each wheel load,from the principle of no iteration or few iterations,completely avoids the "virtual leg",overload,and oscillation problems in feedback control.It can greatly improve the vehicle’s passability,maneuverability,and stability when passing through complex roads.(2)Improvement of optimal wheel load distribution algorithm and simulation verification.First,the shortcomings of the original optimal wheel load assignment algorithm are investigated,and the results obtained by this method may not be globally optimal for some special wheel load assignment expectations.Therefore,it is further improved based on the forced wheel load and nonlinear constraints,respectively.Then,the algorithm is verified and numerically simulated for several special working conditions,and the results are analyzed and compared to prove the correctness and feasibility of the improved algorithm.(3)Principle validation platform for off-road multi-axis vehicles is built.With the design goal of simulating the moving multi-axis vehicle,the principle verification platform of the off-road multi-axis vehicle including the equivalent model of the three-axis vehicle,the virtual road display and loading system,the front road pre-scanning system,and the upper and lower computer control system is built.The control strategy program is completed in the upper and lower bit control system to prepare for the experimental verification.(4)Experimental verification of multi-axis vehicle off-road environment passability.Carry out coupled control experiments on the built experimental platform under the scenarios of three-axis vehicles passing pits unilaterally,passing triangular symmetric speed bumps,and V-shaped speed bumps.The experimental results show that the coupled control theory of body posture and wheel load distribution can precisely control the body height-posture and wheel load within the optimal interval,and can control the load synchronously according to the driver’s expectation with good convergence and no obvious oscillation,which confirms the correctness and superiority of the proposed theory and strategy.In this paper,the coupled control theory of body height-posture and wheel load distribution is investigated from three aspects: theory,simulation,and experiment.It significantly enhances the capability of special vehicles to achieve high mobility,high trafficability,and high stability,and lays the foundation for future vehicles to pass quickly and perform special tasks in complex geographical areas. |
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