Étude et optimisation d’un actionneur à aimant permanent programmable pour des applications robotiques

Abstract

Actuators are a central component of robotic systems, particularly for applications requiring safe and precise physical interaction with the environment. Conventional electromagnetic architectures, mainly based on brushless DC motors combined with mechanical transmissions, nonetheless exhibit significant limitations in low-speed, high-torque operating regimes. Main taining a static torque requires continuous power supply, leading to substantial thermal losses, while the use of transmissions degrades mechanical transparency, control bandwidth, and overall energy efficiency. This thesis investigates an alternative to these conventional architectures through the study and optimization of a programmable permanent magnet actuator (PPM). This type of actuator exploits passive magnetic interactions to generate and maintain static torque without continuous energy consumption. The torque output and equilibrium position of the actuator are defined by the magnetic state of a reconfigurable Halbach structure, programmed using short-duration, high-intensity current pulses. The work first focuses on the development of a design methodology for impulse magnetization circuits, through the analysis of scaling laws governing key electrical parameters such as resistance, inductance, capacitance, and damping factor. Several circuit topologies are studied in order to identify an optimal trade-off between stored energy, peak current, and magnetization robustness. This methodology is then applied to the design of the PPM magnetization circuit. An extensive experimental study of the magnetic circuit is also conducted, with particular emphasis on the impact of magnet discretization, magnetic material selection, and geometric sizing of Halbach arrangements. The influence of demagnetizing fields and current attenuation phenomena during magnetization is experimentally characterized, enabling the optimization of energy consumption and torque performance. The potential of the PPM is demonstrated through its integration into a practical robotic application. A safe robotic gripper is developed to evaluate the actuator’s ability to modulate gripping force, maintain a grasp without electrical power, and respond effectively to external disturbances. Experimental results confirm the relevance of the PPM for robotic applications requiring low energy consumption, robust physical interaction, and dynamic adaptation of mechanical behavior. In addition to the study of the PPM, this thesis also presents the design and evaluation of an interior permanent magnet synchronous motor (IPM) intended for robotic applications. This motor aims to provide an optimized conventional electromagnetic alternative for typical robotic operating conditions by combining high torque capability, good efficiency, and improved mechanical robustness compared to surface-mounted permanent magnet motors. Finite element analysis is performed to compare the performance of the IPM motor with that of a surface mounted permanent magnet synchronous motor of equivalent geometry. The results show a significant extension of the speed range, accompanied by a reduction in the produced torque, which is experimentally validated. This thesis thus contributes to a deeper understanding of programmable permanent magnet actuators and optimized permanent magnet motors for robotics, and provides design tools enabling their integration into advanced robotic systems.

Date	27 Mar 2026
Original language	French
Awarding Institution	École de technologie supérieure
Supervisor	Vincent Duchaine (Supervisor)