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“ Minimization and Enhancement of BLDC actuators for applications on Mechanical Systems by implementing Mechanical Field Weakening method ”
Research Motivation
The purpose of our study is not only building an actuator but enhancing the performance by applying field weakening. The advantage of this development is that we can control the motor run limitations. This technique can be applied to many fields of industry, say robotics, and one can control the use of resources of the system. Precedent study has been made about field weakening, but there are limitations. As for electrical methods, complex control systems are required leading to high cost, while mechanical methods are mostly studied for large actuators which limits the field of application.
Limitations of Prior Studies
Electrical Field Weakening
Figure shows a control block scheme of a BLDC motor utilizing the electrical field weakening method, known as field-oriented control. This separates the flux generating current and torque generating current to control the amount of back EMF generated. However, electrical methods require complex circuitry and digital control systems, thus leading to an increase of cost of the system.
Mechanical Field Weakening
Mechanical field weakening methods are usually implemented on the actuator by adding an extra mechanism that can move the elements inside the motor. However, many applications show the mechanism installed outside the motor, or even in cases where the mechanism is inside the actuator itself, most cases they are passive systems. Passive mechanical field weakening may satisfy the compact design of the actuator, but as a trade-off, we cannot control the motor’s performance by the control system.
Milestones
Mechanical Field Weakening Integration
Integrate the mechanism that enables mechanical field weakening for the actuator to reduce size and increasing the integrity of the actuator for simplicity in the mechanical system.
Minimization
Current study in mechanical field weakening is focused on large size motors that can be applied on electrical vehicles. Our objective is to reduce the size of the motor design to extend the field of application.
High Level Goals
To apply actuator on robotics, a lot of transmissions are used. For example, the figure is about applying actuator with transmission on prosthetic robotic hand. The reason why transmission is used to get proper angular velocity of the motor.
Without using transmission, by mechanical field weakening, we can achieve continuous gear ratio, compact system, and easy hardware control. To achieve mechanical field weakening applied actuator, we will develop our research from conceptual design, detailed design, optimization, and CAE analysis. Lastly, we will apply our actuator on 1-DOF robotic arm to verify performance.
This is a research about using 1-DOF robotic arm to test BLDC actuator. Likewise, we are planning to make these experiment setting to verify our actuator performance.
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