基于力反馈的液压柔顺驱动器补充能量控制

Supplement Energy Control for Hydraulic Compliant Actuator Based on Force Feedback

在大型足式机器人的驱动系统中,使用液压柔顺驱动器进行补充能量控制可以极大地提高机器人的续航能力,因此具有很强的实用价值。首先通过扫频的方式分别得到驱动器输出端空载状态位置频率特性曲线和输出端静止状态力频率特性曲线,然后通过MATLAB的ident系统辨识工具箱进行模型辨识得到较准确的驱动器数学模型。基于上述模型采用自抗扰力控制器,实时估计扰动及对其进行有效的补偿,取得了较好的力控制效果,进而通过力控制将液压缸等效为变刚度弹簧。建立液压柔顺驱动器中液压能、驱动器能量和热能三种能量的动态模型,并对简化运动过程中三种能量之间的转换规律进行分析。基于变刚度策略对运动过程进行了补充能量控制,提高了能量使用效率。不同负载质量和不同液压缸刚度情况下的水平方向运动试验结果验证了上述控制策略的有效性。

In the actuation system of large legged robots, the supplementary energy control of hydraulic compliant actuator can greatly improve the robot endurance, which has strong practical value. The displacement frequency characteristic curve without load and force frequency characteristic curve with the fixed output displacement are obtained respectively and firstly by frequency sweep, and then the accurate mathematical model of the actuation system is obtained through the identification toolbox of MATLAB ident. The active disturbance rejection controller is adopted to estimate the perturbation in real-time and compensate the disturbance effectively based on the above mathematical model. A better force control effect is obtained. And then the hydraulic cylinder is equivalent to a variable stiffness spring through the force control. The three energy dynamic models of the hydraulic energy, the energy of the actuator and the heat energy are built for the hydraulic compliant actuator, and the energy conversion law of these three energies is analyzed for the simplified movement. The adjustable stiffness strategy is used to fulfil the supplement energy control during the movement, and the energy efficiency is improved. The experimental results of horizontal motion with different load mass and different stiffness of hydraulic cylinder show the effectiveness of the above control strategy.