An accelerometer-based joint angle sensor for heavy-duty manipulators

An indirect, self-calibrating, easy to install, and robust joint angle sensing method for heavy-duty manipulators is presented in this paper. This method is suitable for the harsh working environment of these machines where conventional contact-type angle sensors cannot be deployed, or problems are associated with their use. The approach is based on processing the outputs of a pair of biaxial accelerometers placed very close to the joint axis on the adjacent links. In the proposed technique, joint angles are obtained without integrating the accelerometer outputs to avoid measurement error accumulation over a long period of time. Two calibration procedures are also described for accelerometers to ensure the accuracy of their measurements. The experimental results attest to the efficiency and accuracy of the new angle sensing mechanism.