Joint failure recovery for snake robot locomotion using a shape-based approach

Snake robots have shown significant locomotion abilities in various challenging environments. Therefore, they are considered good candidates for search-and-rescue and inspection applications. Their expected working environment may cause the problem of actuator malfunction, which in turn leads to task failure. As actuator replacement or maintenance is not always possible in these difficult-to-reach environments, a control strategy that enables the robot to resume its motion (using the remaining actuators) is highly needed. In this paper, we introduce a shape-based recovery control approach for snake robots with joint failure. In the proposed method, the motion is recovered by restoring the overall desired shape of the robot via controlling the neighbor joints of the failed one. The controlled joints form a so-called recovery part which works to eliminate the effect caused by the failed joint. The recovery part restores the desired robot shape and thus allows the robot to carry on the desired motion. We derive recovery controllers considering locked-joint and free-joint failures. The approach is also extended to cover the double failure case, where two failed joints are considered during movement. The validity of the proposed method is verified in the simulation environment. We apply the recovery controller for several failure scenarios considering different locations of the failed joint. The results show the effectiveness of the proposed method to regain the robot shape and resume the locomotion desired.