Inertial Sensor-Based State Estimation of Long-Reach Flexible-Link Manipulators

In this paper, we study the performance of a finite-element-based observer in estimating the flexural degrees of freedom (DOF) of a single-link flexible long-reach manipulator. The observability of the system confirms that all the flexural states of the system can be estimated using a single angular velocity measurement. The inputs to the observer are obtained from retrofittable and low-cost inertial sensors suitable for mobile machines. Results of the observer's performance with different measured states and varying loads are provided. Validation of the end-point position is carried out using an OptiTrack camera system. The performance of the estimated variables as feedback signals in high-performance control is demonstrated using a nonlinear model-based controller based on the virtual decomposition control framework. The test setup consists of a hydraulically driven 4.5-meter-long beam having a maximum tip mass of 70 kg, resulting in a static deflection of -56.7 cm. The initial experiments on the 1-DOF system indicate that the proposed method is effective.