Force Control Of Polishing Robot End Pneumatic Actuator

The degree of automation of industrial production lines is increasingly high, which, on the one hand, is the inevitable requirement of liberating and developing the productivity, on the other hand, also the real needs to satisfy the gradually increasing quality requirements of standardized industrial product. In one of the categories of the industrial production process, it requires the final surface treatment of work pieces, such as deburring, grinding, polishing or grinding. In this type of process, in order to replace manual forces with automation processes, the industries currently take the common practice of introducing the industrial robots to replace the current manual forces. In the process of grinding and polishing, the quality of polishing tools is not only directly affected by the relative position and movement between the polishing tool and the work piece, but also by the interacting surface contact force. This is concerned with a very challenging area of research, interactive control of the robot and the environment. It gives rise to high accuracy requirements about position control of robot, in the meantime, the ability to adjust the end position of a robot based on environmental changes. Given the crucial influence of contact force on the polished effect, this paper is mainly about the issues related to contact control, and different control strategies to accomplish compliant contact control approach and results are analyzed. This paper seeks to redesign the end effector of the robot system, on the premise of no modification of the robot self-body, to contribute to improve robots the ability to control it contact force with environments.First, this paper describes the background and significance of the study to the topic. Then it briefly reviews the relevant research in the field of the status quo. After constituting the dynamic analysis model for the main component in the pneumatic system, pneumatic directional proportional valves and pneumatic actuators(cylinders), we set up a practical model for system friction. With these preparations, a series of different control methods are discussed. First of all, we ignore the effects of friction, with a linearized controlled object, to construct open loop transfer function of a linear system, and have undertaken a preliminary analysis with selected parameters values of the system. Then, a method based on the control of terminal velocity was introduced to achieve the open-loop force control for contact force. This is an indirect methods. And then another indirect method was introduced. This article continues with the classic impedance control and actuator output pressure control to achieve closed-loop relay control for contact force method. To some extent, these methods can be used to meet certain requirements of the initial need for control of contact force, and is easy to implement, but we also noticed that these classical methods also depend on access to fully understanding of environmental information. Given the fact that in the mechanical systems, friction and load often mostly may become the uncertainties in the system, adaptive control method is a popular control strategy to deal with uncertainty or slowly changing parameter of dynamic systems. This paper design a model reference adaptive controller to compensate uncertainty of friction and effective load in pneumatic system, while for the inner force control loop sliding model controller was used. Numerical simulations have been done for the verification of effectiveness of the control system design. At the same time, we build the actual physics system, program codes for motion control and PC software interface, to accomplish the position and contact force control for the robot end pneumatic actuators.