Design Optimization of

Three-Dimensional Wire Arrangement

Considering Wire Crossings for Tendon-driven Robots

IROS2025

Robots generally have a structure that combines rotational joints and links in a serial fashion. On the other hand, various joint mechanisms are being utilized in practice, such as prismatic joints, closed links, and wire-driven systems. Previous research have focused on individual mechanisms, proposing methods to design robots capable of achieving given tasks by optimizing the length of links and the arrangement of the joints. In this study, we propose a method for the design optimization of robots that combine different types of joints, specifically rotational and prismatic joints. The objective is to automatically generate a robot that minimizes the number of joints and link lengths while accomplishing a desired task, by utilizing a black-box multi-objective optimization approach. This enables the simultaneous observation of a diverse range of body designs through the obtained Pareto solutions. Our findings confirm the emergence of practical and known combinations of rotational and prismatic joints, as well as the discovery of novel joint combinations.


Design Optimization of Three-dimensional Wire Arrangement Considering Wire Crossings

The overview of the three-dimensional wire arrangement optimization considering wire crossings and feasible joint torque space.

The body structure considered is a two-link three-dimensional structure. By placing the start, relay, and end points of the wires on each link, this structure is actuated. The task is to achieve a given joint angle trajectory. Therefore, a sequence of joint angles is provided. Here, it is required that no wire crossings occur along the trajectory and that sufficient feasible joint torque is ensured. The goal of this study is to explore a wire arrangement that satisfies these conditions.

We arrange M wires on the structure, with each wire having N start, relay, and end points.


Simulation Results

The sampling results, design solutions, and torque evaluation for simulation experiments on a 2-DOF joint at N={2, 3} and M=3.

The sampling results, design solutions, and torque evaluation for simulation experiments on a 2-DOF joint at N={2, 3} and M=4.

The sampling results, design solutions, and torque evaluation for simulation experiments on a 3-DOF joint at N={2, 3} and M=4.

The sampling results, design solutions, and torque evaluation for simulation experiments on a 3-DOF joint at N={2, 3} and M=5.

The sampling results, design solutions, and torque evaluation for simulation experiments on a 3-DOF joint at N={2, 3} and M=6.


Bibtex

@inproceedings{kawaharazuka2025arrange3d,
  author={K. Kawaharazuka and S. Inoue and Y. Sahara and K. Yoneda and T. Suzuki and K. Okada},
  title={{Design Optimization of Three-Dimensional Wire Arrangement Considering Wire Crossings for Tendon-driven Robots}},
  booktitle={2025 IEEE/RSJ International Conference on Intelligent Robots and Systems},
  year=2025,
}
            

Contact

If you have any questions, please feel free to contact Kento Kawaharazuka.