Vibration Characteristics and Control Algorithms for Semi-Active Suspension of Space Exploration Vehicles

Suspension systems are an integral part of land vehicles and contribute significantly to the vehicle performance in terms of its ride comfort and road holding characteristics. In the case of Space Exploration Vehicles (SEVs), the requirement of these unmanned vehicles is to rove, collect pictures and transmit data back to the earth. This is generally performed with the help of exteroceptive, and proprioceptive sensors mounted on the main chassis of the SEV. The design of various components of such vehicles is dictated by the assumption of extreme terrain and environmental conditions that it might face. The Mars Exploration Rovers (MERs) have incorporated the use of the “Rocker-Bogie” mechanism for the suspension system which provides relative stability to the MER for various maneuvers. In this work, the “Rocker-Bogie” mechanism is modeled and simulated as a planar kinematic model using parameters of the Perseverance rover. It is found that the Rocker-Bogie tends to nullify the effects of uneven terrain by maintaining the chassis at a relatively fixed location with respect to the ground reference frame. Further, an attempt is made to replace the mechanism with a passive and semi-active suspension module at four corner wheels to study the effects that the semi-active suspension would have on the chassis dynamics of the MER. Lastly, a comparative analysis of the vertical acceleration of the chassis using different suspensions was performed. This concluded that the rocker-bogie mechanism does help to stabilize the chassis dynamic behavior to a greater extent. Future work could include an attempt to utilize the rocker-bogie chassis dynamics as the ideal condition to develop control strategies that can improve the chassis dynamics if individual semi-active suspension systems were employed.