Robust Motion Control of Industrial Robot Based on Robot Parameter Identification and Feedforward Control Considering Resonant Frequency

In control application of industrial robot manipulator, a two-inertia resonant system is normally represented as the basic plant model for various control schemes. Various control techniques with partially feedback linearization have been proposed to achieve high performance motion control. The design of such controllers basically relies on system mechanical parameters. The proper parameters of the model cannot be obtained by the parameter identification based on only manipulator force and motion measurements. In this paper, the open-loop resonant frequency characteristic of the flexible joint is employed to identify the proper mechanical parameters of the two-inertia model. The nominal link inertia and spring constant of gear drive can be readily measured by this novel identification method. The identified parameters are used in independent-joint controller design for conventional PD control scheme and robust control scheme to verify the effectiveness of the proposed identification method. Moreover, the accuracy improvement of the proposed robust control scheme based on feedforward inverse dynamic compensation and D-PD position control gives support the validity of the proposed identification method.