A Model-Free Extremum-Seeking Approach to Autonomous Excavator Control Based on Output Power Maximization
A Model-Free Extremum-Seeking Approach to Autonomous Excavator Control Based on Output Power Maximization
复制标题
基于输出功率最大化的挖掘机自主控制无模型极值搜索方法
DOI：
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发表时间：
2019
影响因子：
5.2
通讯作者：
H. Asada
中科院分区：
文献类型：
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作者：
Filippos E. Sotiropoulos;H. Asada
提出了一种新的自主挖掘机控制方法，使机器能够适应未知的土壤特性。与传统的力控制或轨迹控制不同，新方法使用力和速度的乘积，即从挖掘机传递到土壤的功率，作为自适应挖掘的信号。使用极值搜索算法，寻找并保持最佳挖掘条件，其中铲斗处的力和速度采取使机器的输出功率最大化的特定组合。在此条件下，系统通过控制挖掘机的臂架来找到最佳挖掘深度。同样在这种情况下，挖掘机的输出阻抗与负载的阻抗匹配，从而将最大功率从机器传输到土壤。理论分析证明了在较弱的假设下，存在一个力和速度的最优组合，并且该组合是唯一的。提出了一种基于递归最小二乘的极值搜索算法，以最大化输出功率。该方法是在一个小规模的原型系统，力矩电机模拟液压执行器的非线性力-速度特性。实验结果表明，该原型能够适应不同的土壤性质和地形轮廓执行挖掘任务。
A new approach to autonomous excavator control that allows the machine to adapt to unknown soil properties is presented. Unlike traditional force control or trajectory control, the new method uses the product of force and velocity, namely, the power transmitted from the excavator to the soil, as a signal for adaptive excavation. Using an extremum-seeking algorithm, an optimal excavation condition where the force and velocity at the bucket take a particular combination that maximizes the output power of the machine is sought and maintained. Under this condition, the system finds the optimal depth of digging by controlling the boom of the excavator. Also under this condition, the output impedance of the excavator matches the impedance of the load and, thereby, transmits the maximum power from the machine to the soil. Theoretical analysis proves that an optimal combination of force and velocity exists and is unique under mild assumptions. An extremum-seeking algorithm using recursive least squares is developed for maximizing the output power. The method is implemented on a small-scale prototype system where torque motors emulate nonlinear force-speed characteristics of hydraulic actuators. Experiments demonstrate that the prototype can execute excavation tasks adaptively against varying soil properties and terrain profile.