تکنیک شکل گیری ورودی مدت زمان متغیر بکارگرفته شده برای کاهش لرزش در یک ربات صنعتی

It is widely and frequently observed that industrial robots conducting fast motion involve serious residual vibration, the period of which varies with time. To address this time-varying residual vibration problem, this paper presents a practical solution based on a time-varying input shaping technique (TVIST). First, to suppress the time-varying vibration, a guideline for designing a practical TVIST is presented. Following the guideline, a TVIST for a heavy 6 DOF industrial robot is designed. In doing so, a simple yet effective equation is derived from robot dynamic equations to schedule the time-varying period. Furthermore, a simple payload-adaptation scheme is also included. Then, experiments are performed by using the TVIST for the industrial robot under spatial motion and payload variation. The experimental results show that the residual vibration is reduced to less than 14% of the original level in magnitude and the time delay caused by pre-filtering is shortened, demonstrating the efficiency and effectiveness of the proposed TVIST.

This paper presents a practical solution to the residual vibration problem frequently and widely found in industrial robots. Provided below are the background and context associated with the problem and our solution approach. It is well known that industrial robots need to achieve higher speed and precision to increase productivity. To this end, one of the major obstacles to overcome is the residual vibration coming from joint flexibility primarily due to the transmissions on the motor axes. Take the example of a heavy industrial robot performing spot welding in an automobile factory. The welding process can only be started after positioning the end-effector to a proper position. However, the robot must wait for the residual vibration to be decayed out before beginning the welding. For this reason, residual vibration increases task execution time thereby decreasing productivity. However, the residual vibration problem is difficult to solve since the residual vibration the robots exhibit tends to be nonlinear and time-varying, owing to configuration1-dependent inertia variation and nonlinear stiffness of the gears. Moreover, the vibration becomes further complicated by the different payloads the industrial robot handles.

For suppression of time-varying residual vibration in industrial robots, a practical design procedure of TVIST is presented and the procedure is applied to an industrial robot. The parameter scheduling rule of the TVIST is practically designed for computational efficiency so that it can be implemented in a system without enough left-over memory and computational power. In designing the TVIST, the period of vibration needs to be scheduled in real-time. By using s–w length as a time-varying variable, the period of vibration at each configuration can be scheduled efficiently. In addition, the TVIST is modified to adapt to various payload. As a result, the proposed TVIST reduces 90% of the residual vibration in magnitude and also shortens the time delay due to filtering.