Introduction If you have ever been to shooting range before, you know

that firing a gun is fun. Time flies when you’re sending hundreds of rounds down range, ejecting shell casings everywhere. When it comes time to pack up and retrieve all those casings, however, time slows to a crawl. But why pick them up yourself when a robot can do it for you? Enter SHELLY, a mobile, autonomous solution to this problem.

SHELLYAutonomous Collection Robot

Collection Bucket

Scoop

Brush

WheelCabinet

Platform A cabinet acts as the main body and houses electronics. Two wheels are used to propel the robot. Plastic ball casters balance the robot and provide smooth

points of contact. A rechargeable battery (>6V) will power the robot. A collection bucket will be placed on the back of the robot.

This will slide off for easy disposal of contents as well as access to the component cabinet.

A dustpan-like scoop will be used to collect the objects and dump them into the collection bucket.

A brush on the front of the robot will sweep objects into the scoop.

Board An Arduino Mega 2560 will be used as the main processor External circuits will be implemented on a custom PCB using

Altium software

Sensors 4 different types of sensors will be used: Analog IR Rangefinders: Three of these will be placed on the

robot, one facing forward and one facing either side angled forward. Used for obstacle avoidance. Read from ADC ports on Arduino.

IR LED/Photo-Transistor: Placed at the very front of the robot. When an object breaks the IR plane, a sweep and scoop is triggered, moving the object into the collection bucket.

Bump Sensors: Several of these will be places at points where the robot is likely to bump into objects, should the IR sensors fail. Read from digital ports on Arduino.

Edge Detectors: Two of these will be placed at the front of the robot to prevent it from driving off an edge. Read from ADC ports on Arduino.

Actuation Four different motors will be used. Two DC motors with shaft encoders will be used for

locomotion, one for each wheel. These motors will be driven from the rechargeable battery and controlled by H-bridges with PWM for speed control. The shaft encoders will ensure the robot drives straight when desired.

A high-torque servo will rotate the scoop 90 degrees in a horizontal to vertical fashion. Gravity will then cause objects to roll into the collection bucket. Controlled by PWM.

Another servo will actuate the brush that sweeps objects into the scoop. Also controlled by PWM.

Special Sensor A front-facing webcam will be used for object detection. Using Visual Studio and OpenCV, the webcam will track both

color and key points to identify shell casings. This information will be sent from the webcam to a laptop

over wifi. Instructions will be sent back to the robot using Bluetooth or

similar wireless communication.

Autonomous Behavior The robot will use its sensors to detect obstacles and avoid

them The webcam will be used to detect shell casings. Once

found, the robot will center itself on the object and drive towards it.

Once the shell casing breaks the IR plane on the front of the robot, the brush will sweep around to ensure the casing rolls into the scoop. The scoops will then lift up, causing the shells to roll into the collection bucket.