Task-based Dynamic Fault Tolerance for Humanoid Robot Applications and Its Hardware Implementation

Abstract

This paper presents a new fault tolerance scheme suitable for humanoid robot applications. In the future, various tasks ranging from daily chores to safety-related tasks will be carried out by individual humanoid robots. If the importance of the tasks is different, the required dependability will vary accordingly. Therefore, for mobile humanoid robots operating under power constraints, fault tolerance that dynamically changes based on the importance of the tasks is desirable because fault-tolerant designs involving hardware redundancy are power intensive. In the proposed fault tolerance scheme, a duplex computer system switches between hot standby and cold standby according to each individual task. However, in mobile humanoid robots, a safety issue arises when cold standby is used for the standby computer unit. Since an unpowered unit cannot immediately start to operate, a biped-walking robot falls down when failover occurs during cold standby. This paper proposes a safety failover method to resolve this issue and describes the hardware design of the safety failover subsystem.