Abstract: Development of dexterous robotic joints is essential for advancing manipulation capabilities in robotic systems. This paper presents a design and an implementation of a tendon-driven robotic wrist joint, together with an efficient Sliding Mode Controller (SMC) for precise motion control. The wrist mechanism is modelled using the Timoshenko-based approach to accurately capture its kinematic and dynamic properties, which serve as the foundation for tendon force calculations within the controller. The proposed SMC is designed to deliver fast dynamic response and computational efficiency, enabling accurate trajectory tracking under varying operating conditions. The effectiveness of the proposed controller is validated through comparative analyses with existing controllers for similar wrist mechanisms. The proposed SMC demonstrated superior performance, validated through both simulation and experimental studies. The Root Mean Square Error (RMSE) range in simulation is found to be approximately 1.67 × 10-2 radians, while experimental validation yielded an error of 0.2 radians. Additionally, the controller achieved a settling time of less than 3 seconds and a steady-state error below 10-1 radians, consistently observed across both simulation and experimental evaluations. Comparative analyses with other controllers confirmed that the developed SMC surpassed alternative control strategies in motion accuracy, rapid convergence, and steady-state precision, contributing to enhanced dexterity. This work establishes a foundation for future exploration of tendon-driven wrist mechanisms and control strategies in robotic applications.

Key words: Tendon-driven robot')">Tendon-driven robot, Robotic wrist, Sliding mode controller, Timoshenko beam theory