Encrypted Feedback Linearization and Motion Control for Manipulator with Somewhat Homomorphic Encryption

Encrypted control is a cryptographic approach to reducing the risks of eavesdropping attacks for networked control systems. An encrypted controller determines control inputs directly from encrypted data without decryption. This study considers an implementation of an encrypted motion controller, which consists of feedback linearization and PD control, for a manipulator using somewhat homomorphic encryption. A controller reconstruction method is proposed for separating a nonlinear time-varying controller into a linear part and a nonlinear part. A plant side device supports encrypted controller operations by generating the nonlinear part in advance of encryption. Simulation results demonstrate that the proposed encrypted control system can achieve the same control performance as the one that an unencrypted control system does.