Design of a Concentrically Stacked Modular Actuator with Forced Air Cooling for Multi-DOF Robotic Systems

Jaeho Noh,Woosung Yang,Sungon Lee,Jaeyong Lee

doi:10.3390/en11112947

Abstract

This paper proposes a concentrically stacked modular (CoSMo) actuator with rotary electric motors to implement multi-degree-of-freedom (multi-DOF) robotic systems with high power densities. The CoSMo actuator shows a novel design concept, which enables the actuator module with an integrated radiator to be combined in series and cooled by a single fan. This unique system has elevated thermal characteristics owing to the heatsink sharing effect. This enables the module to carry higher current by decreasing the temperature-rise rate. Also, the proposed design concept reduces the number of components required for cooling and allows the actuator to be placed concentrically, which contributes to the system having low mechanical impedance and higher power output per unit mass. The thermal characteristics and feature of the CoSMo actuator were analytically and numerically verified by simulation using a simplified model. To advance the thermal characteristics of the system further, the adequate actuator types for the CoSMo actuator were analyzed and a prototype was fabricated based on the analysis. Through the experiment using the prototype, we verified that the maximum continuous current that can be applied to the CoSMo actuator is up to about three times greater than the rated current in a forced air-cooling environment.

Highlights

With the recent advances in electromagnetic motor systems, the scope of their application as core power-generating components in robotic and automotive applications has progressively expanded.With the advent of the Fourth Industrial Revolution in particular, there has been a rising demand for performance upgrades and functional diversification of electromagnetic motor-driven industrial and service robots
Because the motor housing of a concentrically stacked modular (CoSMo) actuator generally consists of a metal with a high thermal conductivity, such as aluminum, the thermal resistance between the modules becomes very small if sufficient pressure exists between the housings [11,12]
Ir is the maximum continuous current when the heat transfer coefficient (HTC) is 3 W/ m2 ·◦ C, which is the minimum of the mean value in natural air convection [16], and im is the maximum continuous current in a certain cooling environment

Summary

Introduction

With the recent advances in electromagnetic motor systems, the scope of their application as core power-generating components in robotic and automotive applications has progressively expanded. With the advent of the Fourth Industrial Revolution in particular, there has been a rising demand for performance upgrades and functional diversification of electromagnetic motor-driven industrial and service robots. This trend has generated a growing interest in the performance improvement of multi-degree-of-freedom (multi-DOF) robot arm systems, along with the need to develop smaller motors with higher power densities [1]. Maximal motor performance greatly varies depending on the thermal management level of the installation environment. A comparison of motor performance based on the output torque per unit mass, which is currently regarded as a reliable indicator of motor performance, demonstrated

Methods

Results

Discussion

Conclusion