轻型机械臂无外置传感器碰撞检测功能的实现

Modeling for Collision Detecting of Light Robotic Manipulator Without External Sensors

在工业以及服务领域中,人机协作型机械臂已经得到了越来越广泛的应用。让机械臂与人共享工作空间的优势是显而易见的,然而在这一过程中,机械臂由于失控而引发机械臂伤人危险的可能性是存在的,如何保证人的安全就变得极为重要。针对这一议题,提出了一种基于关节电流变化来检测是否有碰撞发生的方法,这一方法摆脱了在机械臂外部加传感器的限制,极大地降低了方案实施的成本。考虑到关节电流会因为机械臂速度的变化以及摩擦力的存在而变得不可预知,提出了一种消除以上干扰的方法。针对判断是否有碰撞发生的检测阈值如何确定这一问题,提出了一种基于机械臂构型变换而变化的可变阈值方法。碰撞检测实验在一台七自由度机械臂上实施,实验结果显示在机械臂对人体产生伤害之前,碰撞可以被检测到。

Physical human-robot interaction and cooperation has become a topic which has drawing much attention. Industrial and domestic applications unifying the workspace of humans and robot will require safe and dependable robot design and control. In order to guarantee human＇s safety during robot manipulation and to reduce cost of sensors, a method for solving collision detecting without force sensors is put forward based on the joints＇ motor current in this paper. Considering that direct calculation of the collision force will introduce noise because of the existence of acceleration and unpredictable frictions, we present a method to eliminate the force mentioned above. For the problem that constant current threshold will cause robotic manipulator to perform different safety protection effect, dynamic threshold is put forward based on the manipulator＇s mechanical configuration and pose position and orientation. Collision experiments are carried out on a 7 - DOF robotic manipulator, results show that the method can detect collision safely and effectively.