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© 2019 River City Rocketry — Louisville, KY

Deployable Rover Payload

Payload Challenge from 2017-2018 NASA Student Launch Handbook:

4.5.1.    Teams will design a custom rover that will deploy from the internal structure of the launch vehicle.

4.5.2.    At landing, the team will remotely activate a trigger to deploy the rover from the rocket.

4.5.3.    After deployment, the rover will autonomously move at least 5 ft. (in any direction) from the launch vehicle.

4.5.4.    Once the rover has reached its final destination, it will deploy a set of foldable solar cell panels.

Rover Orientation Correction System (ROCS)

The ROCS is a unique bearing system designed to support the rover payload throughout the flight of the launch vehicle and ensure upright orientation of the rover after landing regardless of the orientation of the payload bay. The bearing rings have been custom designed and machined by the team out of tool steel. The bridging sled connecting the two rings has been precisely cut using a CNC water jet.

Rover Locking Mechanism (RLM)

The RLM is a device that retains the rover payload in

the airframe of the launch vehicle throughout the flight. A loading arm matches with a bracket on the rear of the rover to lock the rover along the central axis of the launch vehicle. This in conjunction with a female T-slot mounted on the ROCS bridging sled and accompanying male T-nut on the bottom of the rover fixes the rover along all axis. After receiving the deployment signal, the rover unlocks the loading arm and drives forward off the T-slot.

Deployment Trigger System

The DTS allows the team to deploy the rover from a linear distance of over 1 mile away. A receiver module has been secured inside the airframe. To mitigate the issue of signal loss through the carbon fiber airframe and ensure signal reception in all directions, a flexible antenna has been wrapped around the exterior of the airframe. A Yagi antenna is being used to directionalize and increase the range of the transmitter signal.

Rover Body Structure

The RBS acts as the main support for all on-board rover subsystems and electronics. The body has been water jet out of aluminum, bent using a manual finger break, and welded along the corners. The body has gone through an anodizing process carried out by the team to dye the aluminum Red Bordeaux.

Rover Drive System (RDS)

The RDS consists of two main drive motors that transfer power to the main drive axles through a set of 90° bevel gears. A set of pulleys and passive wheels guide a custom designed tread as it drives the rover forward. The split saw-tooth, polyurethane tread with a high friction coating has been designed to maximize the climbing ability and traction of the rover on all terrains, both wet and dry.

Obstacle Avoidance System

The OAS is a lidar sensor mounted to the front of the rover for the purpose of detecting insurmountable objects in the path of the rover and determining a path to avoid the obstacle. Custom designed 3D printed mounts allow the sensor to be attached to a micro servo motor that increases the field of view of the sensor to 180°. An algorithm has been written to determine the path of least obstruction for the rover to turn to in the event that an object is detected.

Solar Array System (SAS)

The SAS is a deployable solar array consisting of 4 thin film, flexible solar panels. The system actuates a tower assembly by releasing a spring hinge giving vertical clearance for the panels to unfold properly and without damage. The system also utilizes a unique rotational deployment method to unfold the array in a cascading manner. After the rover has reached its final position at least 5 feet away from the launch vehicle, the array will be deployed and begin harvesting solar energy that will be used to trigger the Surface Imaging System.

Surface Imaging System (SIS)

The SIS has been added as a secondary mission of the payload to embrace the mindset of the rover challenge of deploying an autonomous rover vehicle on a foreign planet to collect scientific data. The system consists of a high-resolution camera module mounted to the same servo motor used by the Obstacle Avoidance System to increase the field of view of the camera and thus, the scientific data collected. The system is triggered to begin sweeping the camera and taking images based on the amount of energy collected by the Solar Array System.

Control Electronics System (CES)

The CES handles all autonomous controls and sensor data for the payload. The system consists of a control stack of 3 boards (a micro-controller, data logging board, and motor driver) along with a set of two high precision inertial measurement units mounted on a custom designed printed circuit board. The system recognizes a unique deployment signal from the DTS, performs a orientation safety check, unlocks the RLM, and commands the rover through its primary and secondary missions. The data logging board records all sensory data, images, and commands during key phases of the mission on a microSD card for analysis after retrieval of the rover.