Grades 3–5 · Machines
How do a Mars rover’s linked legs cross uneven ground?
A Mars rover must travel where there are no smooth roads. Its six wheels are connected to the body by jointed supports called a rocker-bogie suspension. Each wheel has its own drive motor, but the support links can turn without a motor commanding every joint.
In the diagramLinked supports share uneven movementLeft 12°From levelRight 0°DifferentialBody angle 6°RockerBogieOne side below: three wheels; six wheels in all
On each side, a long rocker joins the front wheel to a shorter bogie. The bogie carries the middle and rear wheels. When a wheel meets a rock or depression, these links pivot so neighboring wheels can remain in contact with different ground heights.
A differential connects the left and right rockers to the body. It shares their motion rather than forcing the body to copy either side alone. In the simplified comparison, a left rocker 12 degrees from level and a right rocker at level give a body angle of 6 degrees.
The result is steadier support during slow travel, not a perfectly level ride. Steep slopes, loose sand and sharp rocks still matter. Engineers plan routes within the rover’s limits.
About this explanation
Starting knowledge: Understand wheels, pivots and the idea that different parts can turn by different amounts.
Sources
- NASA — Perseverance Rover Components: Wheels and Legs