Research On Passive Five Bar Collaborative Robot

Cobots (collaborative robots) are a kind of novel special robots, which possess the advantages of conventional robots such as higher task precision, better bearing loads capacity and high agility and facility of an operator. Cobots are intended for direct physical interaction with a human operator in a shared workpace, so they can relieve of task intensity, improve task precision and work efficiency. The Cobot in the paper has passive and constraint charactristics, whose servomotors are applied to modify the ratio of velocities between the joints, rather than actuate joints move. So it can steer motion direction and speed of the endpoint, and furthermore implement the trajectory control of the endpoint. The operator supplies the power of Cobot moving when collaborating with a Cobot, while loading gravity and trajectory control are carried by the Cobot. The Cobot possesses widely application foreground such as "Intelligent Assist Devices" (IADs), surgery operations, telepresence of virtual reality and teleoperation, and daily life and so on.The research work is a project funded by NSFC (National Natural Science Foundation of China), which is "The research of key technology for passive collaborative robot (Cobot) ". The main objective is to develop the Cobot which has passive and constraint characteristics, which includes Cobot architecture, control system, dynamics characteristic, control strategy , prototype of the Cobot and experiments of the Cobot.The paper reviews the present situation of the Cobot field domestically and abroad at first. After analyzing and comparing with architectures, running principles and control modes of current Cobots, the architecture, control system project and control strategy of a five-bar Cobot are put forward.According to the features of Cobot and its control requirements the nonholonomic constraint transmission (NCT) is designed which consists of two unilateral overrunning clutches and two DC servomotors (with worm reducer). The NCT possesses passive and velocity constraint characteristics by making useful of unilateral overrunning speciality of clutch and reverse self-locking...