A New Model-free Robust Adaptive Control of Cable-driven Robots

For high performance control of cable-driven robots, a new model-free robust adaptive control is proposed using adaptive proportional-integral-derivative nonsingular fast terminal sliding mode (PID-NFTSM) in this paper. The designed control scheme has three elements, which are time-delay estimation (TDE) and a new PID-NFTSM manifold and a combined adaptive reaching law. The TDE element is applied to achieve the lumped system dynamics and hence founds a practical model-free structure. Meanwhile, a new PID-NFTSM manifold is designed to inherit the advantages of the NFTSM and high-order SM (HOSM) and integral SM (ISM) controls. Because of this design, the PID-NFTSM manifold can effectively ensure the non-singularity and high comprehensive control performance. Then, by combining the fast-TSM-type reaching law and a constant speed one with adaptive gain, we design a new combined adaptive reaching law for performance reinforcement. Benefiting from above three parts, our proposed control is model-free, highly precise and strongly robust. Stability is analyzed using Lyapunov theory. The effectiveness of our control is proved by comparative simulation studies.