针对铰接农用车在变附着系数路面条件下的路径跟踪精度难以保证的问题,提出了引入侧滑补偿的非线性模型预测控制(Nonlinear Model Predictive Control,NMPC)算法。首先,构建了考虑侧滑补偿的铰接农用车二自由度运动学模型,并基于该模型...针对铰接农用车在变附着系数路面条件下的路径跟踪精度难以保证的问题,提出了引入侧滑补偿的非线性模型预测控制(Nonlinear Model Predictive Control,NMPC)算法。首先,构建了考虑侧滑补偿的铰接农用车二自由度运动学模型,并基于该模型在Simulink中构建了NMPC控制器,最后以Adams环境中的虚拟铰接农用车为被控对象,以农业典型的地头转弯路径为参考路径,开展了变附着系数路面条件下的试验验证。结果表明,该算法的跟踪误差最大约为0.03 m,能够实现铰接农用车在变附着系数路面下的高精度路径跟踪。展开更多
In a system based on the phase lock loop（PLL）, a trade-off must be made between the tracking precision and the dynamic performance if constant parameters are adopted. To overcome this drawback, a new method called n...In a system based on the phase lock loop（PLL）, a trade-off must be made between the tracking precision and the dynamic performance if constant parameters are adopted. To overcome this drawback, a new method called no phase slipping adaptive bandwidth（NPS-AB） is proposed, which can adjust the loop bandwidth adaptively for different working conditions. As a result, both the tracking precision and the dynamic performance can be achieved concurrently. NPS-AB has two features to keep the loop stable： one is the capability of quick response to dynamics; the other is a series of additional constraints when the bandwidth is switched. Compared with other methods, there is no phase slipping during the adjustment process for NPS-AB. The phase integer ambiguity can be avoided and the phase value is kept valid. It is meaningful for carrier ranging systems. Simulation results show that NPS-AB can deal with sudden dynamics and keep the pseudo-range value stable in the entire dynamic process.展开更多
Based on previous achievements,a dynamic pressure-sinkage equation for saturated clay is established.First,aquasi-static penetration rate is selected,and the ratio of the dynamic penetration rate to the quasi-static r...Based on previous achievements,a dynamic pressure-sinkage equation for saturated clay is established.First,aquasi-static penetration rate is selected,and the ratio of the dynamic penetration rate to the quasi-static rate is used to characterize the degree of dynamic effect,then theβth power of the ratio is used to quantify the dynamic effect of sinkage.The dynamic effect exponentβis obtained using penetration tests with different penetration rates.Then,a dynamic motion resistance equation for a tracked vehicle is established based on the dynamic pressure-sinkage equation.The equation incorporates both penetration and bulldozing resistance.Finally,a series of simulation experiments with varying travel speeds and slip rates is carried out.The results show that an increase in the speed leads to stronger terrain stiffness,resulting in a decrease in sinkage and motion resistance.However,the enhancement effect becomes weaker with an increase in the travel speed.展开更多
文摘针对铰接农用车在变附着系数路面条件下的路径跟踪精度难以保证的问题,提出了引入侧滑补偿的非线性模型预测控制(Nonlinear Model Predictive Control,NMPC)算法。首先,构建了考虑侧滑补偿的铰接农用车二自由度运动学模型,并基于该模型在Simulink中构建了NMPC控制器,最后以Adams环境中的虚拟铰接农用车为被控对象,以农业典型的地头转弯路径为参考路径,开展了变附着系数路面条件下的试验验证。结果表明,该算法的跟踪误差最大约为0.03 m,能够实现铰接农用车在变附着系数路面下的高精度路径跟踪。
文摘In a system based on the phase lock loop（PLL）, a trade-off must be made between the tracking precision and the dynamic performance if constant parameters are adopted. To overcome this drawback, a new method called no phase slipping adaptive bandwidth（NPS-AB） is proposed, which can adjust the loop bandwidth adaptively for different working conditions. As a result, both the tracking precision and the dynamic performance can be achieved concurrently. NPS-AB has two features to keep the loop stable： one is the capability of quick response to dynamics; the other is a series of additional constraints when the bandwidth is switched. Compared with other methods, there is no phase slipping during the adjustment process for NPS-AB. The phase integer ambiguity can be avoided and the phase value is kept valid. It is meaningful for carrier ranging systems. Simulation results show that NPS-AB can deal with sudden dynamics and keep the pseudo-range value stable in the entire dynamic process.
基金Supported by the National Natural Science Foundation of China(51005018)
文摘Based on previous achievements,a dynamic pressure-sinkage equation for saturated clay is established.First,aquasi-static penetration rate is selected,and the ratio of the dynamic penetration rate to the quasi-static rate is used to characterize the degree of dynamic effect,then theβth power of the ratio is used to quantify the dynamic effect of sinkage.The dynamic effect exponentβis obtained using penetration tests with different penetration rates.Then,a dynamic motion resistance equation for a tracked vehicle is established based on the dynamic pressure-sinkage equation.The equation incorporates both penetration and bulldozing resistance.Finally,a series of simulation experiments with varying travel speeds and slip rates is carried out.The results show that an increase in the speed leads to stronger terrain stiffness,resulting in a decrease in sinkage and motion resistance.However,the enhancement effect becomes weaker with an increase in the travel speed.
