rockerbogie

The rocker-bogie suspension is a passive wheel locomotion system used on several Mars rovers to improve stability on uneven terrain. It was developed by NASA's Jet Propulsion Laboratory to keep the rover body level while distributing loads across the wheels, enabling traversal of rocks, ditches, and soft soil without excessive tilting or wheel slip.

On each side of the rover, a rocker arm is mounted to the chassis and connected to a bogie that carries two wheels. The rocker and bogie form a two-link suspension, and a differential connects the two sides to balance weight transfer. When a wheel encounters an obstacle, the motion is shared through the linkage so that the other wheels adapt, keeping other wheels in contact with the ground and reducing the risk of getting stuck. In six-wheeled rovers, the front wheel is attached to the rocker, while the middle and rear wheels are mounted on the bogie.

History and usage: The design first appeared on the Mars Pathfinder mission with the Sojourner rover and was subsequently used on the Spirit and Opportunity rovers and the larger Curiosity rover. It remains a defining feature of many modern Mars rovers, including Perseverance, though some rover variants have slight architectural changes to suit newer instruments and mass requirements.