Robotic disassembly of a permanent magnet DC brushless motor

Liang, Chaozhi (2025). Robotic disassembly of a permanent magnet DC brushless motor. University of Birmingham. Ph.D.

Preview

Liang2025PhD_Redacted.pdf
Text - Redacted Version
Available under License All rights reserved.
Download (14MB) | Preview

Abstract

Globally, the transition to electric vehicles (EVs) is accelerating. As these EVs reach the end of their service life, large quantities of valuable components, including electric motors, need to be remanufactured to achieve a more sustainable circular economy. Disassembly, the first step in the remanufacturing process, typically requires human intervention due to difficulties in automating it. This thesis investigates the robotic disassembly of a permanent magnet DC brushless motor. Six typical tasks are defined in motor disassembly, and four of them are studied, including the ‘Press-in’ task, ‘Press-on’ task, Unplugging task and Coil disassembly task.
Related to methodology, an analytical model implementing the magnetomotive force method was developed to calculate disassembly forces when removing a rotor with permanent magnets from a stator. This model provides reasonable accuracy in a very short calculation time without requiring high-performance computers compared with the finite element method. The average error rates of the FE method and MMF method are 16.7% and 26.3 %, respectively. By determining the material magnetic hysteresis, the improved analytical model predicts the force optimal positions, adapting to different cases of magnetic fields on the rotor with permanent magnets. Additionally, potential robotic solutions for the press-fit component disassembly tasks and the Coil disassembly task were investigated and experimentally validated.
A robotic cell, including two collaborative robots, a set of tools and two devices for disassembling press-fit components, is designed to fully automate the disassembly process. The disassembly quality in the robotic process is superior to that in the manual process, preventing unnecessary damage to the components. The time of the robotic process is 886 s at full capacity, which is 56.93% faster than that of the manual process (1390 s).
Robotic disassembly offers significant potential for advancing the circular economy in EV remanufacturing. However, although robotic automation improves disassembly efficiency and sustainability, it faces economic barriers due to high equipment costs. Future research should focus on cost-reduction strategies, expanding task automation, and hybrid approaches that combine robots and humans.

Type of Work:

Thesis (Doctorates > Ph.D.)

Award Type:

Doctorates > Ph.D.

Supervisor(s):