TARA (ThunderOps Advanced Remote Avatar) is a robotics platform based on a used electric wheelchair. In some states old electric wheelchairs are cheap and readily available due to legislation that prevents them from being reused as medical devices. In TARA's case her base was acquired at auction for $50. Most used wheelchairs end up in landfills... but they are a fantastic platform for building useful robots.
Electric wheelchairs are built with medical grade motors, wheels, and electronics. They are built to be reliable and long-lasting. Most of them use Lead-Acid batteries which are available everywhere and are easily recycled when they wear out. Most wheelchairs can carry over 300 pounds and can travel over 6 miles on a charge.
TARA has been a regular at Maker Faire Detroit since 2015. During that time she has gone through a few revisions.
2015: Rev 1 - TARA used WIFI for control and she had no voice. She could be controlled from a tablet using a web page that was published from her adhoc WIFI base. Her main MCU was a Beaglebone Black running Linux with an Arduino Uno used to trick the wheelchair controller into thinking it was a joystick. Unfortunately WIFI control proved to be a bad choice for a robot at Maker Faire. She worked great right up until the crowds poured in. The radio traffic from all of the phones made it difficult for TARA to be controlled. She ended up warming the bench at our booth.
2016: Rev 2 - TARA was converted to use an RC transmitter and reciever for control. Modern RC transmitters have great range and use protocols that reject interference. This was a great choice for crowded venues. (Though you still need to be careful with any radio control.)
Rev 3 - TARA got a voice but her speakers were small. If there was any noise nearby it was difficult to hear what she was saying.
2017: Rev 4 - TARA got a cheap but punchy audio system so she could be heard better. In addition she got a subwoofer shaped like a rocket on her back. Now she is at her best when people dance with her.
2019: Rev 5 - TARA's electronics bay had become so cluttered with wires it became difficult to exhibit how she functions. In addition the wired connections had become glitchy due to vibration as she rolls around. In this revision she is getting a new electronics enclosure and a PhaseDock Workbench. She has also shed her original wheelchair controller and is now using RC control direct to a BasicMicro RoboClaw motor controller. This will improve her control responsiveness and reliability.