Design of linear electromechanical actuator for automatic ambulatory Duodopa pump

Abstract

This paper focuses on the design of a linear electromechanical actuator (EMA) to be used in conjunction with a positive displacement piston-type drug dispensing syringe pump. The motivation behind this work is the development of an automated ambulatory Duodopa pump, which necessitates the design of an EMA to safeguard Parkinson's disease (PD) patients from bradykinesia and dyskinesia problems that occur due to the inability of traditional Duodopa pump in optimal drug delivery. The proposed EMA consists of a lead screw mechanism driven by a DC servo motor coupled with gears. The lead screw is designed in such a way that the rule of thumb and self-locking property are obeyed to avoid the back-driving phenomenon. The overall performance of the proposed EMA is evaluated by in-silico studies, which results in better dynamic response, stability, and reliability. The in-silico analysis of various electrical, as well as mechanical faults that are prone to happen in EMA, is also discussed in this paper. The stability of the proposed system is analyzed via frequency response plots under different load inertia values and system time delays. From the stability analysis, it is perceived that an excessive inertia mismatch or time delay may lead to instability issues in the system, even though stability is guaranteed at present. The proposed methodology emphasizes a crucial condition in the DC motor sizing that the optimum operation requires an inertia ratio as close to 1:1 as possible.

Keywords

• Actuator faults
• Automatic ambulatory Duodopa pump
• Electro-mechanical actuator
• Dopamine
• Parkinson’s disease
• Stability