Design of articulated leg–wheel subsystem by kinetostatic optimization

• Exploring the use of various candidate articulated leg-wheel subsystem designs to enhance locomotion capabilities of land-based vehicles.
• Employing systematic kinetostatic design approaches coupled with optimization to determine the link length/spring constant parameters.
• Achieving the greatest motion-ranges between wheel-axle and chassis.
• Reducing the overall actuation requirements by spring assist.

High mobility, maneuverability and obstacle-surmounting capabilities are highly desirable features for rough-terrain locomotion systems. In this paper, we explore the use of various candidate articulated leg–wheel subsystem designs (based on the four-bar mechanism) to enhance locomotion capabilities of land-based vehicles. Multiple leg–wheel design parameters, such as kinematic link lengths and static spring stiffnesses and preloads, influence the overall locomotion performance. Appropriate selection can not only enhance the robot climbing performance but also reduce the wheel slip as well as the overall energy consumption.In particular, we aim to: (i) achieve the greatest motion-ranges between wheel–axle and chassis; as well as to (ii) reduce the overall actuation requirements by aspring assist. Hence, we explore the use of systematic kinetostatic design approaches coupled with optimization to determine the parameters for alternate leg–wheel subsystem designs. Further, we also examine enhancement of uneven-terrain locomotion by varying subsystem parameters during the terrain traversal via a semi-active leg–wheel subsystem. Extensive simulation is then employed to evaluate the capabilities of these alternate articulated leg–wheel designs to surmount a predetermined/sensed terrain traversal profile while reducing actuation requirements.