Design

The robot is 18 inches x 18 inches and 10 inches tall. The frame is two layers and is made of 1 x 3 inch planks and 1/4 inch plywood. Motors are mounted under the lower layer. The lower layer contains the battery, fuse block and motor controller. The upper layer contains switches, voltage regulator and controllers. Wheels are mounted inbound of the frame and protrude through the first layer.

Drive

The robot uses two salvaged auto wiper motors for drive. These motors are mounted to two 8 inch outdoor rubber wheels on the sides of the robot and in the middle of the frame. the front and rear of the robot have casters that allow the robot to rotate on it's center axis.

Electronics

Power is provided by a 12 volt 7 amp hour sealed lead acid battery. The battery is connected to a fuse block through a master shutoff switch. 12 volt power is sent to the motor controller and on to the motors. A 5 volt power regulator is connected to the fuse block. This regulator provides power to all microcontrollers on the robot.

Control

There are four controllers on the robot. The master controller is a Raspberry Pi which runs a Clearpath ROS image. One microcontroller is an ESP32 and provides motor control. The other two microcontrollers are Arduino Nanos. One of the Nanos interfaces to 5 ultrasonic sensors while the other provides IMU positioning data. All microcontrollers connect to the master controller as ROS nodes over ROS serial connections.

Teleop

There is a teleop node on the robot that allows remote control. The robot can be controlled over Wifi from a browser or from a customer controller. The custom controller is built using a Nintendo Wii controller connected through an ESP32 microcontroller.

Sensors

The robot can monitor up to five ultrasonic sensors. An IMU provides position data. Encoders have been developed and are being added to both wheels. These current working prototype encoders made from small magnets and hall effect sensors.