While presenting many advantages in application, the loss of actuators also brings about great challenge to the control of underactuated systems. Specifically, the unactuated DOFs (degrees of freedom) cannot be directly controlled, instead, they have to be stabilized indirectly through appropriate regulation of actuated ones. As an unfortunate fact, the natural couplings between actuated and unactuated states are often relatively weak. Hence, in many practical cases, even the actuated states are well regulated, the performance of the unactuated states still fails to meet expectations. Such phenomenon is particularly obvious when the system faces various disturbances, since the unactuated states are more vulnerable to them and more difficult to be re-stabilized. To deal with the aforementioned issues, a nonlinear gain-adapting controller is proposed for a class of underactuated mechanical systems, which incorporates extra unactuated states-related information into the controller to enhance the state couplings. In this way, the closed-loop system reacts more appropriately and efficiently to the unactuated dynamics, which is expected to obtain improved transient performance and robustness. With a relatively concise structure, the proposed strategy imposes few requirements on the system configuration, which makes it more convenient for practical application. Theoretical analysis and experiment results are presented to demonstrate the performance of the proposed method.

尽管在应用中显示出许多优点，但执行器的丢失也给欠驱动系统的控制带来了巨大挑战。具体来说，未激活的自由度（自由度）不能直接控制，相反，必须通过对已激活的自由度进行适当的调节来间接稳定它们。不幸的是，激活状态和未激活状态之间的自然耦合通常相对较弱。因此，在许多实际情况下，即使激活状态也得到很好的调节，未激活状态的性能仍然无法达到预期。当系统面对各种干扰时，这种现象尤其明显，因为未激活状态更容易受到干扰，并且更难于重新稳定。为了解决上述问题，针对一类欠驱动机械系统，提出了一种非线性增益自适应控制器，该控制器将额外的与未激活状态相关的信息整合到控制器中，以增强状态耦合。以此方式，闭环系统对未激励的动力学有更适当和有效的反应，这有望获得改善的瞬态性能和鲁棒性。该策略结构相对简洁，对系统配置的要求不高，在实际应用中更加方便。理论分析和实验结果表明了该方法的有效性。闭环系统会对未动态响应做出更适当，更有效的反应，从而有望获得更高的瞬态性能和鲁棒性。该策略结构相对简洁，对系统配置的要求不高，在实际应用中更加方便。理论分析和实验结果表明了该方法的有效性。闭环系统会对未动态响应做出更适当，更有效的反应，从而有望获得更高的瞬态性能和鲁棒性。该策略结构相对简洁，对系统配置的要求不高，在实际应用中更加方便。理论分析和实验结果表明了该方法的有效性。