Bee swarms and power consumption

A project log for HaptiVision

A haptic vest for orientation for the blind

JanTharJanThar 09/03/2017 at 20:380 Comments

One importand part to consider is that vibration motors make noise, something which isn't intended and should be reduced as far as possible. it will otherwise undermine the invisible tool effect of the vest, might cause confusion on nearby people and will disturb the audio channel of the wearer, who might want to use it also for orientation (bat echolot). With the first version, we had a big issue with sound, we even made a sign on one exhibition with a warnign "bees inside", since whenever sombody passes the vest on short distance, most of the motors went on full power and gave a corresponding sound.

With the next version we had less coupling effects between the motors, and for using a normal power pack with limited current instead of a racing battery pack we also had to reduce power consumption. Therefore we decided to drive  - apart from the normal PWM driving of each motor - only few motors at the same time on each driver circuit, drastically reducing both power consumption and noise.

At the moment each half of the vest (64 vibration motors and their driver circuits) is powered with  one 1A USB port of the power pack, Realsense and Up-board on another 2.4 A port - with a 18200 mAh power bank we could run the system for almost 8h on exhibitions, with  a neglectable noise level.