Remotely controlled mobile robots are important examples of Cyber-Physical Systems (CPSs). Recently, these robots are being deployed in many safety critical applications. Therefore, ensuring their cyber-security is of paramount importance. Different control schemes that have been proposed to secure such systems against sophisticated cyber-attacks require the exchange of secret messages between their smart actuators and the remote controller. Thus, these schemes require pre-shared secret keys, or an established Public Key Infrastructure (PKI) that allows for key agreement. Such cryptographic approaches might not always be suitable for the deployment environments of such remotely mobile robots. To address this problem, in this paper, we consider a control theoretic approach for establishing a secret key between the remotely controlled robot and the networked controller without resorting to traditional cryptographic techniques. Our key agreement scheme leverages a nonlinear unknown input observer and an error correction code mechanism to allow the robot to securely agree on a secret key with its remote controller. To validate the proposed scheme, we implement it using a Khepera-IV differential drive robot and evaluate its efficiency and the additional control cost acquired by it. Our experimental results confirm the effectiveness of the proposed key establishment scheme.

翻译：远程控制移动机器人是信息物理系统（CPS）的重要实例。近年来，此类机器人被部署于诸多安全关键型应用场景，因此确保其网络安全至关重要。针对复杂网络攻击，现有多种控制方案通过智能执行器与远程控制器间交换秘密消息来实现系统防护，但这些方案需要预共享密钥或建立允许密钥协商的公钥基础设施（PKI）。此类密码学方法未必适用于远程移动机器人的部署环境。为解决该问题，本文提出一种控制理论方法，在不采用传统密码技术的情况下，在远程控制机器人与其网络控制器之间建立密钥。本密钥协商方案利用非线性未知输入观测器与纠错码机制，使机器人能够安全地与远程控制器协商共享密钥。为验证所提方案，我们基于Khepera-IV差动驱动机器人实现该方案，并评估其效率及引入的额外控制代价。实验结果表明了所提密钥建立方案的有效性。