基于计算力矩法的机械臂滑模鲁棒控制

Sliding mode robust control for robotic manipulators based on computed torque method

  • 摘要: 针对机械臂系统中存在的未建模动态与外部扰动问题,提出一种基于计算力矩法的滑模鲁棒控制算法。首先,采用计算力矩法对机械臂的非线性动力学进行前馈补偿,建立名义线性化系统;其次,引入滑模控制策略,确保系统跟踪误差沿预定滑模面动态收敛,并利用饱和函数替代符号函数,有效抑制滑模控制固有的高频抖振现象;再次,设计额外的鲁棒干扰补偿项,增强系统对集总干扰(包含外部扰动与模型不确定性)的鲁棒性和抑制能力;最后,通过比例-微分(proportional-derivative, PD)控制律优化滑模控制增益矩阵,提升闭环系统的瞬态响应速度与稳定性。为验证所提算法的有效性,在仿真环境中设置了3种典型工况,并施加随机干扰。以计算力矩法滑模控制和基于扩张状态观测器的自抗扰滑模控制作为对比算法。评估体系包含4项关键跟踪性能指标及系统总能耗指标。仿真结果表明,相较于两种对比方法,所提出的基于计算力矩法的滑模鲁棒控制算法显著提升了控制性能,各项性能指标数值平均降低超过10%,同时系统总能耗更低。结果表明,所提出的控制方法能有效提升机械臂在复杂扰动环境下的轨迹跟踪精度、鲁棒稳定性及能量利用效率。

     

    Abstract: To address the challenges of unmodeled dynamics and external disturbances in robotic manipulator systems, a sliding mode robust control algorithm based on the computed torque method is proposed. The core design comprises employing the computed torque method for feedforward compensation of the manipulator's nonlinear dynamics to establish a nominal linearized system. Sliding mode control is introduced to ensure dynamic convergence of tracking errors along a predetermined sliding surface, utilizing a saturation function instead of the sign function to effectively suppress inherent high-frequency chattering. An additional robust disturbance compensation term is designed to enhance system robustness and suppression capability against lumped disturbances, which encompass external perturbations and model uncertainties. The sliding mode control gain matrix is optimized via a proportional-derivative control law to improve the transient response speed and stability of the closed-loop system. For algorithm validation, simulations were conducted under three typical operating conditions subject to random disturbances. Computed torque method-based sliding mode control and active disturbance rejection sliding mode control utilizing an extended state observer served as comparative controllers. The evaluation framework incorporated four key tracking performance metrics and total system energy consumption. Results demonstrate that, compared to the two comparative methods, the proposed computed torque method-based sliding mode robust control algorithm significantly enhances control performance. Key performance metrics exhibit an average reduction exceeding 10%, alongside lower total energy consumption. This indicates the proposed method's efficacy in improving trajectory tracking accuracy, robust stability, and energy utilization efficiency for manipulators operating in complex disturbance environments.

     

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