Lunar Rover Design Challenges - Size, Weight and Locomotion

Building a robotic rover that can operate on the lunar surface is a complex process.  It has to survive tremendous temperature variations, it will be exposed to many kinds of radiation, it has to be very light, it has to be strong enough to climb over rocks and out of craters, it cannot tip over, it must be very reliable, and it needs to carry or generate its own electrical power.  Our engineers and researchers will have to experiment and design around these challenges in order to achieve a good compromise between these competing characteristics.

Here are some of the rover challenges that we are working on.  Each section describes our design challenges and some of the trade offs and compromises that we must explore.  Each section also contains links to other websites containing additional information about each topic.  As we explore our options and build our test prototypes our “final” design will keep changing over time.  Some of our design evolution can already be seen in the pictures on our rover webpage http://www.rocketcityspacepioneers.com/space/space-rover.


Size & Weight - Lunar Rover Design Challenges

We are focusing on a small light weight rover.  This will provide significant savings in our launch rocket and lunar lander’s thrusting capabilities.  A small rover also forces our engineers to keep things as simple as possible because there simply is not enough room for complex ideas.  Simplicity tends to increase reliability by reducing the number of things that can go wrong. 

  • http://en.wikipedia.org/wiki/Rocket_engine

Locomotion  - Lunar Rover Design Challenges:
We plan to use very tiny DC electric motors connected to wheels to move the rover.  Tiny electric motors typically spin very fast, require little electrical power, but do not have much torque (torque: strength of rotation).  Tiny motors will help us to reduce our rover’s weight and help us to save our limited electrical power for other systems.

  • http://en.wikipedia.org/wiki/Torque
  • http://electronics.howstuffworks.com/motor.htm
  • http://en.wikipedia.org/wiki/Brushed_DC_electric_motor


The drawback is that these motors do not have enough torque to move our rover by themselves.  So we will connect them to a transmission (a.k.a gearbox) just like a car.  This transmission will add a little weight and size but we will still come out lighter and smaller than if we had used a larger motor instead.  The gears inside of the transmission will convert the rotationally weak and fast spinning output axle of the tiny motor into a rotationally strong but slow spinning wheel axle.  Our rover builders are still experimenting in order to balance our torque needs and the available electrical power in order to find the perfect motors.

  • http://en.wikipedia.org/wiki/Gear
  • http://en.wikipedia.org/wiki/Transmission_(mechanics)
  • http://science.howstuffworks.com/transport/engines-equipment/gear.htm
  • http://www.howstuffworks.com/gears.htm


We are also in the very early stages of investigating a combination of wheels attached to 3 or more movable legs.  This is a more complex and risky design but it means that the rover could traverse rougher terrain than a standard wheeled car type body.

Lunar rover Design Gearboxes
Gearbox drive train of a prototype rover.


Lunar Rover design Gearboxes
Close up of gear box.


Charles Tullock
Rover Systems Integrator
Dynetics


Learn More:
Lunar Rover Sensors and Communications
Lunar Rover Environmental Issues


 

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