Reducing the Power Consumption of an IMU-Based Gait Measurement System

This paper presents our approach to reducing the power consumption in our Gait Measurement System (GMS), which is the foundation for various monitoring and assistive systems. Our GMS is a small foot-mounted device based on an Inertial Measurement Unit (IMU), containing an accelerometer and a gyroscope. It can compute gait parameters in real-time, including cadence, velocity and stride length, before transmitting them to a nearby receiver via a radio frequency (RF) module. Our power saving strategy exploits the cooperation between both hardware and software. By realizing on-chip computing, reducing RF usage and enabling sleep mode, the GMS’s current consumption was dramatically reduced. In active mode, the GMS consumes about 2.1mA, while in standby mode, the current is only 20 A. Powered by a small rechargeable 110mAh battery, we expect the GMS to last for months of normal usage without recharging; a duration necessary for our intended applications in e-health.