Bistabilities in turning are characterized by the process being stable for small perturbations and unstable for larger ones. These bistabilities occur due to nonlinearities in cutting force characteristics. Characterizing these bistabilities can guide selection of cutting parameters to lie outside these zones of conditional instabilities. However, if cutting is targeted in the bistable regions, or in regions that are globally unstable, active damping methods may need to be pursued to improve the stability envelopes. Since gain tuning for active damping of chatter vibrations is usually based on linear stability analysis, it would be useful to know if those gains are adequate for damping chatter in the presence of bistabilities that occur in processes prone to strong perturbations. However, experimentation on machines to investigate these bistabilities and/or tune gains to meet targeted productivity levels with active damping is difficult due to the destructive nature of chatter. This paper hence discusses the use of a hardware-in-the-loop (HiL) simulator to emulate bistabilities and to serve as a test bench for gain tuning in the presence of bistabilities. The HiL simulator has a hardware layer comprising a flexure representing a flexible workpiece, and two actuators. One emulates the cutting force calculated in real-time in the software layer. Another serves as the active damper operating with a velocity feedback control law. Bistabilities for three different nonlinear force models are experimentally illustrated on this HiL simulator. We show that active damping can stabilize these bistable regions. Since the width of the bistable regions depend on the nonlinear force characteristics, our investigations reveal that gains must be tuned for the force model and the static chip thickness under consideration. These results are useful and can instruct active damping strategies during more realistic cutting processes with nonlinear force characteristics that exhibit conditional instabilities in the presence of strong perturbations.

转动的稳定性的特征在于，对于小扰动，该过程稳定，而对于大扰动，该过程不稳定。这些双稳态由于切削力特性的非线性而发生。表征这些双稳态可以指导选择切削参数，使其位于这些条件不稳定区域之外。但是，如果将切割目标定在双稳态区域或全局不稳定的区域，则可能需要采用主动阻尼方法来改善稳定性包络线。由于对颤振的主动阻尼进行的增益调整通常基于线性稳定性分析，因此，如果在容易发生强烈扰动的过程中存在双稳态，则了解这些增益是否足以阻尼颤振将很有用。然而，由于颤振具有破坏性，因此很难在机器上进行实验以调查这些双稳态和/或调整增益以达到具有主动阻尼的目标生产率水平。因此，本文讨论了使用硬件在环（HiL）模拟器来模拟双稳态并用作在双稳态存在时进行增益调整的测试平台。HiL模拟器具有硬件层，该硬件层包括代表挠性工件的挠曲件和两个致动器。一个可以在软件层中模拟实时计算的切削力。另一个用作根据速度反馈控制律运行的主动阻尼器。在此HiL模拟器上通过实验说明了三种不同的非线性力模型的双稳态。我们表明主动阻尼可以稳定这些双稳态区域。由于双稳态区域的宽度取决于非线性力的特性，因此我们的研究表明，必须针对力模型和所考虑的静态切屑厚度来调整增益。这些结果是有用的，并且可以在更现实的切削过程中以非线性力特性指示主动阻尼策略，该非线性力特性在强烈扰动的情况下表现出条件上的不稳定性。