The OMNi Is a Small, Modular Robot Capable of Doing Some Incredible Things
With just an arm and a mobile platform, the OMNi robot performs tasks within exhibits that humans would find too mundane.
Inspiration for the OMNi
Museums are excellent places to go when trying to explore new topics or to simply interact with a couple fun exhibits, but the sheer size of some can be difficult for both staff and visitors alike. The primary issue is that there is a large number of electronics displays and other equipment which must be checked in the morning and throughout the day periodically, and having a staff member check every single one takes a lot of time to complete. For visitors, some might have difficulty in finding their way around the museum, so having an automatic tour guide would also free up staff for other tasks.
A team of two people from EDM Studio in Vancouver (Will Donaldson and Darran Edmundson) sought to build a robot that can do all of the above and more while also having the ability to swap out modular components quickly. Their solution involves using a custom robot with a suite of sensors and manipulators that can cruise around a museum's floor to carry out different actions as needed, all while moving on a set of omni wheels- hence the name "OMNi".
Constructing a prototype
The very first version of OMNi consisted of a simple triangular platform that had a single omni wheel mounted on each of its three corners. This was important since the robot had to be capable of moving around people and obstacles with plenty of agility. The base had a lead-acid battery that connected to the electronics up top that read incoming sensor data and made movement decisions to control the motors.
Chassis version 2
Because the robot would be around people for nearly the entire day, a new chassis was needed. Version two had a similar layout but ditched the triangular wooden base for a circular aluminum one, although the motors were still in the same configuration. Next, an acrylic plate was cut and attached to the base with a set of metal rods for holding the electronics. And finally, a top aluminum plate was machined with many holes for mounting robotic arms and sensors for modularity.
Moving around the floor
Power is provided to the robot by a single 12V 14Ah BLD14-12 battery, and its output is passed through a fuse for safety and then a 12V to 5V regulator for the electronics. The three DC motors are each driven by an individual MD10C module that receives current from a relay for immediate cutoff in the case of an emergency. In order to give the Raspberry Pi positional feedback data, each motor is also connected to a closed-loop PID controller and Arduino Nano pair that measures the RPM of the motor and sends the values over I2C.
Adding some intelligence
A robot without sensors is blind, which would be incredibly harmful if it is to be used around people. This is why Donaldson and Edmundson added a LIDAR module to the second-from-the-top plate that performs a scan once every second and updates its internal map using simultaneous location and mapping (SLAM) algorithms. However, this alone is not enough because the robot is moving too fast for the LIDAR data to catch up. Therefore, an inertial measurement unit (IMU) was also added that interpolates the robot's last-known position with where it is headed to avoid nearby obstacles.
Other features
Apart from autonomous navigation, the team needed a way to control the robot manually as well, so they came up with two different methods: a handheld controller or a keyboard. There was also an alternative ZeroTier SSH connection that allows for a user to remotely control the robot over the internet through a variety of schemes. Feedback is provided to the driver via a single Raspberry Pi High Quality Camera module.
When OMNi is next to an exhibit, it can use its onboard robotic arm to automatically touch the screen to see if it turns on or to move objects around. Currently, it lacks feedback sensors and useful tools, meaning that it only exists as a proof of concept for now.
The final feature of the OMNi robot is a set of two metal plates on the base that allow the robot to bump against a dock to charge without the need for human intervention.
Using it in a museum
To solidify the need for such a robot, the team encountered an exhibit that was working properly when viewed via its remote desktop, but failed when seen in person, indicating a display issue. This problem was only detected by a set of human eyes noticing the blank screen, but in the future, OMNi could check automatically and determine if something is broken on its own.