Shuai Liu刘帅
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Cable-Driven Parallel Robot

Design, modeling, and trajectory optimization of a cable-driven parallel robot (CDPR) for additive manufacturing.

HKUST · Manufacturing and Aerospace Automation Lab · CASE 2023 / Mechanism and Machine Theory 2025

Graphical abstract from the supplied PDF, showing the CDPR design and comparisons of tracking and printing performance under gust disturbances
Graphical abstract: robot design, anti-disturbance trajectory generation, and experimental results. Open full PDF ↗

The challenge

Cable-driven robots offer a flexible, scalable approach to large-workspace manufacturing. Cable elasticity and external forces can displace the printing nozzle, making accurate tracking difficult. Outdoor applications introduce an additional challenge: wind disturbances.

For printing tasks that constrain nozzle position but leave some freedom in orientation, that freedom can be used to improve the robot’s resistance to disturbances.

The approach

  • Model the mechanism. Relate cable geometry, tension, and elasticity to the end-effector pose and nozzle position.
  • Quantify disturbance sensitivity. Use a variation-based analytical framework to evaluate directional stiffness and the effect of external forces.
  • Optimize orientation. Generate an anti-disturbance trajectory (ADTG) while maintaining the required nozzle path.
  • Make it practical. Fit sampled orientation optimization results with a shallow neural network for efficient implementation.

Simulation & experimental validation

The method was evaluated using dynamic simulation and a physical CDPR with a printing end effector. Laser-tracker measurements capture nozzle motion; impact-hammer tests assess frequency response; gust experiments compare ADTG with tension-considering compensation (TCMC).

End effector with wind baffles, tracking target, IMU, and gust source in the experimental setup
Gust-rejection setup with baffles on the end effector and a tracking target for motion measurement.
Printing experiment video from the project presentation.

What the experiments show

Optimizing orientation improves directional stiffness and nozzle tracking under gusts. Surface scanning of the printed parts provides a second way to evaluate the effect on manufacturing quality.

0.3857 mmRMS surface height
TCMC baseline
0.0928 mmRMS surface height
Proposed ADTG method

Values from the scanned printed-part comparison in the project presentation (slide 21), describing this experimental condition.

Related publications

Shuai Liu and Molong Duan. Cable-driven parallel robot trajectory generation with optimized orientation considering disturbance rejection. Mechanism and Machine Theory, 210, 106016, 2025.
Read paper ↗

Molong Duan, Jiaquan Feng, and Shuai Liu. Design, manufacturing, modelling, and control of a cable-driven parallel robot for additive manufacturing. IEEE CASE, 2023.
Read paper ↗

Graphical abstract ↗