The paper presents a novel strategy to control the instantaneous rotational velocity of a planar slider subject to a soft contact with friction and to external loads, including gravity. The approach is based on a novel model that combines the LuGre dynamic friction model with the limit surface concept for two main reasons. First, the limit surface allows considering both translational and rotational sliding motions. Secondly, the actual friction provided at the contact by the LuGre dynamic model exhibits dependence on the rate of variation of the external loads and, thus, it is worthwhile in dynamic conditions. Slipping control is realized by acting on the friction forces through the normal load so as to stably regulate the velocity of the slider to zero. The control law exploits a nonlinear observer, based on the proposed model, to estimate the instantaneous rotational velocity of the slider, which is used to compute the normal load necessary to ensure a globally asymptotically stable equilibrium of the slider. Experimental results show the effectiveness of the approach in an application of robotic manipulation using an industrial gripper sensorized with force/tactile sensors.

本文提出了一种新颖的策略来控制平面滑块的瞬时旋转速度，使其经受与摩擦的软接触以及包括重力在内的外部载荷。该方法基于一种新颖的模型，该模型将LuGre动摩擦模型与极限表面概念相结合，主要有两个原因。首先，限制表面允许同时考虑平移和旋转滑动运动。其次，LuGre动力学模型在接触处提供的实际摩擦表现出对外部载荷变化率的依赖性，因此在动态条件下是值得的。滑动控制是通过作用于法向载荷下的摩擦力来实现的，以便将滑块的速度稳定地调节为零。控制律基于提出的模型开发了非线性观测器，估计滑块的瞬时旋转速度，该瞬时旋转速度用于计算确保滑块整体渐近稳定平衡所需的法向载荷。实验结果表明，该方法在使用带有力/触觉传感器的工业抓手进行机器人操纵的应用中是有效的。