Performance analysis on radiation degraded BLDC motor in robot servo systems

Abstract

For humanoid robot applications in nuclear radiation environments, not only the electronic and mechanical parts, but also the servo system in robots could be damaged by large dose of radiation. In this paper we study the radiation induced degradation to the brushless DC (BLDC) motor in the robot servo systems and analyze how its performance changes due to radiation induced demagnetization. The radiation demagnetization factor is introduced into the electromagnetic model of the BLDC motor, and the motor performance under the PWM control method is compared with the one without radiation degradation. The result illustrates that the radiation will decrease the motor power and cause controlability loss in the robot servo systems.

Performance degradation estimation of robot in highly radioactive environment: Servo Motor Control

“…where݇ is the power coefficient determined by the power of radiation source, ݀ ሚ (ߠ) is an random B-field intensity reduction ratio following the distribution ܰ ෩ (ߤ, ߪ ଶ ) , in which ߤ is the average reduction ratio, ߪ ଶ the variance of the same parameter.Our research in [16] has shown that the value of ݀ߖ ݀ߠ ⁄ always vary by a greater extent than the magnetic flux density ‫.ܤ‬ Therefore, the motor back-emf constant ‫ܭ‬ , will nolonger be a constant, but a number varying with the motor angular position.…”