Virtual Prototyping of a Cable-Driven Compliant Robotic Wrist

This article details the virtual prototyping of a cable-actuated robotic wrist with two degrees of freedom (DOFs). These DOFs are achieved using two pairs of Cross Axis Flexural Pivot (CAFP) compliant transmission elements (CTEs), along with passive rolling contacts that guide deflection and protect the CTEs from buckling. Developing a virtual prototype allows for testing the behavior of the prototype in various scenarios without the cost of building a physical model. This approach helps in selecting the appropriate actuation system for specific applications in advance. Moreover, a fast-operating virtual prototype enables the exploration of suitable control strategies and parameter adjustments without risking the physical prototype. Thus, having a computationally efficient model is crucial. This study describes the creation of a quasi-real-time virtual prototype based on Finite Element Analysis (FEA) results. Simplifying the model by replacing flexible actuation cables with rigid counterparts, substituting CTEs with their reaction forces from deformation, and using constraints to mimic passive contacts and ensure correct component trajectories, along with implementing a friction estimation model based on Euler-Eytelwein’s formula, allowed to achieve a computational time reduced by 99.98%. Additionally, a multi-software control algorithm was integrated to fine-tune parameters and estimate the system’s response speed.