In this paper, a novel autonomous mobile robotic arm is presented that can autonomously follow mobility impaired patients and provide protection against backward and sideway falls. The arm is equipped with a Lidar sensor to estimate the subject distance and orientation for autonomous tracking. An end-effector with is designed to prevent backward and sideway falls when the subject becomes unbalanced. The robot is tested experimentally to demonstrate that it can effectively follow a subject and limit backward and sideway falls.