# A Cable-Driven Hybrid Robot with Series-Parallel Coupling: Design, Modeling, Optimization Analysis, and Trajectory Tracking

## TL;DR

This paper introduces a new hybrid robot combining serial and parallel cable systems for complex tasks, with modeling, optimization, and calibration methods.

## Contribution

A novel cable-driven hybrid robot with series-parallel coupling and methods for modeling, workspace analysis, and self-calibration.

## Key findings

- A modular CDHR design with an 8-cable parallel drive and a 4-DOF serial manipulator was developed.
- Optimized anchor seat positions improved the statics and force-closure workspace analysis.
- Experimental validation confirmed the effectiveness of the proposed methods in simulations and a physical prototype.

## Abstract

Compared to purely serial robots or cable-driven parallel robots (CDPRs), cable-driven hybrid robots (CDHRs) combine the advantages of both, addressing their limitations and enabling the execution of complex tasks. The series-parallel coupling structure increases the complexity of the system, complicating modeling, calibration, and force-closure workspace (FCW) analysis. This study develops a CDHR system equipped with various sensors and proposes methods for series-parallel coupling modeling, workspace analysis, and self-calibration of complex systems. First, the modular design requirements for the CDHR are analyzed, comprising an 8-cable parallel drive and a 4-degree-of-freedom serial manipulator. Second, a kinematic model of the CDHR with series-parallel coupling was derived, and the positions of the dynamic anchor seats were optimized using an optimization algorithm. Based on these optimized results, a modeling and analysis method for the statics and FCW is proposed. Furthermore, considering the complex and interdependent structural parameters of the system, a method for the self-calibration of the system parameters and trajectory planning for the CDHR is presented. Finally, experimental validation on both simulations and a physical prototype confirmed the effectiveness of the proposed methods. The developed prototype and the proposed method provide a basis for high-precision operations in large spaces, operations in dangerous/extreme environments, and automated operations in logistics/warehousing.