State Estimation of a Partially Observable Multi-Link System with No Joint Encoders Incorporating External Dead-Reckoning

This paper presents a technique for state estimation of a multi-link system having no joint encoders, which can only be partially observed by a camera. To fully observe the system without changing the current configuration, a gyroscope and an accelerometer are attached to each link as dead-reckoning sensors. Observations of the dead-reckoning sensors are associated with the states of the multi-link system such that the states are fully observable. The camera, which observes part of the system globally, is used as a global corrector in the framework of an extended Kalman filter to filter the dead-reckoning errors accumulated over time. Parametric studies in simulation have investigated and identified the efficacy of the proposed technique in estimating the state of the multilink system. Experimental validation using a two-link arm has demonstrated the applicability of the proposed technique to real-world multi-link systems.