Coordinated Voltage Conversion and Low-Power Micro-Actuator Switching

Abstract

Due to very low power throughput and behavior as primarily capacitive loads, voltage conversion for micro-scale piezoelectric and electrostatic actuators can be very inefficient, while analog drive circuit supply currents may also exceed actuator power consumption. When limited instead to switching commands at discrete time instants to control micro-actuator motion, it may be advantageous to coordinate operating periods of any voltage conversion circuitry with actuators. A sample scenario of a traditional boost converter driving a thin-film piezoelectric micro-robotic appendage along a trajectory is considered through simulation studies. Some ranges of target motion accuracy are achieved using less energy, up to a 25% reduction at 30 V, for a 4 V battery, when coordinating voltage converter operation, even when conversion efficiency is very low.

Modeling Cyclic Capacitive Loading of Thin-Film Batteries

“…MEMS-based micro-robots, for example, must operate under very strict power limits and with finite power system payload capacity. Often, electrical circuitry for low powered application can also be very inefficient, 17 requiring additional battery capacity which can come at a premium in the often "footprint limited" area of MEMS. Moreover, some of the most common MEMS transduction mechanisms (i.e.…”

“…electrostatic, piezoelectric) act as primarily capacitive loads resulting in high-speed, high-current intermittent discharge from batteries, which is both less common and less desirable in most larger-scale battery applications. Piezoelectrically-actuated walking micro-robots, 17,18 give a platform for understanding these types of loading conditions having mid-range operating frequencies (10 1 -10 3 Hz) and small capacitances (10 −10 -10 −8 F). As stated above, the purpose of this work is to adapt existing modeling approaches to capture cyclic, capacitive loading of thin-film batteries.…”

Thin-film piezoelectric and high-aspect ratio polymer leg mechanisms for millimeter-scale robotics

“…For example, power densities of solid-state Li-ion batteries can exceed 100 W/kg, but once packaging and other components are taken into account, effective power densities of existing millimeter-scale batteries are less than 10 W/kg (General Electronics Battery Co. 2011;Cymbet Corp. 2016). Even if higher power densities can be maintained in future micro-batteries, it is also true that substantial power may be required to accommodate sensing, computation, and inefficiencies of power electronics (Edamana and Oldham 2014;Oldham et al 2011).…”