Rover Project

Prototype Rover

Created in: SolidWorks 2020

Summary

This project was started in April 2021, where I set out to design and 3D model my own explorer rover, with the motivation coming from the Mars Perserverence Rover, which had touched down 2 months prior. This rover is designed to be used for general terrain traversing and land-surveying, with it being able to also store test & research equipment. It is equipped with Intel RealSense Cameras and more cameras/equipment will be added in the future. The rover's current design features 360 degrees turning on all 4 wheels with full-spring suspension for both legs.

This is the first design iteration of this rover design. I plan on continuing to improve it as I progress through my degree and gain more experience/knowledge with mechanical design.

Motivation

At the start of 2021, the Mars Perseverance Rover touched down on the surface of Mars, exactly on February 18, 2021. It then proceeded to send back high-resolution images of the Martian surface and just a few days later, sent full video footage of its descent and landing on the Martian surface. I have always been fascinated by space exploration and NASA’s ongoing space exploration projects, and the Perseverance rover was no exception, as the technology and engineering that went into producing such an advanced and capable rover were innovative. As a result, I was inspired by this innovative rover and tasked myself with designing and modelling my own rover with the knowledge I had at the time.

Objective

To design and 3D model my own Rover in Solidworks, that would replicate the basic functions of a rover
Incorporate my own unique mechanical design components and other additions

Criteria

Must have a versatile mounting plate
Must have 4 wheel steering
Must have suspension on both axles
Must be powered by 4 motors at each wheel
Must be constructed of lightweight material

Constraints

Suspension travel of 50 cm
Total weight less than 10kg
Motor must have a max speed of 2000+ rpm

Approach

The following project was completed through multiple stages. The first stage was the research stage, where research was done online to find existing rover designs and analyze the Perseverance Rover to draw inspiration from to make the initial sketches of my rover design. After this initial design concept was sketched out, I started incorporating approximate dimensions to each component. Then I started converting these concepts into 3D CAD models on SolidWorks by breaking down the rover into multiple mechanical sub-assemblies and modelling each of those sub-assemblies separately. I then created a larger assembly and mated all sub-assemblies together, and made appropriate changes to dimensions and tolerances to ensure all the mechanical parts were fitted appropriately.

This resulted in the first 3D model of my rover (Fig 1a), with all the main mechanical components in place. Through further revision, research and design alterations, more mechanical components and additional components were added to the rover, such as a stronger leg assembly for the rover (Fig 1c), improved suspension block assembly (Fig 1b), altered steering assembly (Fig 1c) and the addition of camera and storage equipment (Fid 1d).

The current version of the rover (Fig 1d) was completed in May, which incorporates improved versions of most of the mechanical sub-systems, as well as the auxiliary components that are used for imaging and controlling all aspects of the motor. Further design iterations are planned for most sub-systems to improve functionality as well as efficiency.

Rover Progression Pictures (April - May)

Components

Suspension Assembly

The current suspension system assembly for the rover features 3 main components; the top suspension block, a lower suspension block and the springs.

The top suspension block, made from titanium, mounts onto the main frame with a set of bolts and features the shafts for the spring to ride along. It also incorporates a cutout for the lower suspension block to move up and down, to maximize suspension travel and absorb shocks from the wheels.

The lower suspension block, made from carbon fibre slots into the posts of the top suspension block and moves up and down based on shocks from the wheels. This lower suspension block is connected to the wheel legs through a set of bolts as well.

Steering Assembly

The current steering assembly features 3 main components; the wheels, electric motors and the steering arm.

There are a pair of electric motors on each wheel, with each motor being different. The main electric motor connects directly to the wheel to power it. The second motor is housed at the top of the steering arm, where it pivots a bearing that is mounted to a plate that rotates the steering arm the appropriate amount of degrees.

The steering arm is responsible for connecting the wheels and wheel powering motor to the steering motor.

Further design alterations for this assembly are planned to make it more robust and functional.

Frame Assembly

The frame assembly features the main frame (pictured above) as well as the top plate. Both are made from titanium. The main frame features a rectangular shape, with a cross support structure in the middle to improve rigidity and minimize weight. The main frame also mates to the suspension assembly through a set of equidistant bolts to ensure a tight fit.

The top plate, made from a thinner titanium, is also bolted onto the main frame. It is intended to house many additional components such as cameras, storage and other equipment.

Auxiliary Components

The additional components on this rover include multiple cameras, power processing units, controllers and other storage components. This rover currently features multiple Intel® RealSense D435 cameras, which are depth and tracking cameras that are able to give machines depth perception abilities. They are also able to 3D map their surroundings. The housings for these cameras were modelled by myself. 3 of these cameras are located on the top plate and one is located pointing downwards in the undercarriage of the rover. The rover also features an undercarriage, housing drivers and controllers for the motors.

Additional Pictures

External Resources/Outsourced Parts Used:

All motors, bearings, springs and controllers were outsourced from McMaster-Carr. The wheels were downloaded from GrabCAD and altered to match my design specifications, but I plan to re-model new ones in the future. The Intel camera was also from GrabCAD, but I created the housing & mount based on my rover.

Wheels (Only Rim & Tire Used): https://grabcad.com/library/rc-car-wheels-1

DC Motor: https://www.mcmaster.com/6627T53/

Driver: https://www.mcmaster.com/6627T81/

Controller for DC Stepper Motor: https://www.mcmaster.com/6627T68/

Intel RealSense CAD Model: https://grabcad.com/library/intel-realsense-d435-3d-camera-1

Compression Springs: https://www.mcmaster.com/9657K322/

Bearings: https://www.mcmaster.com/60355K604/

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