This paper presents the kinematic synthesis of a steering linkage that changes track, wheelbase, camber, and wheel height in a turn, while maintaining Ackermann geometry. Each wheel is controlled by a 5-SS platform linkage, which consists of a moving platform connected by five SS chains to the vehicle chassis. Ackermann steering geometry ensures all four wheels will travel on circular arcs that share the same center point. S denotes a spherical or ball-in-socket joint.
The kinematic synthesis problem is formulated using seven spatial task positions. The procedure computes the SS chains that guide the platform through the seven task positions, and examines all combinations of five that form a single degree-of-freedom linkage. A kinematic analysis identifies the performance of each design candidate, and eliminates functional defects.
In the design process, the task positions are modified randomly within constraints in order to find a useful mechanism design. Mechanisms are deemed useful if they travel smoothly through all seven task positions. Upon analyzing 1000 sets of task positions, only 10 useful mechanisms were found. A second iteration produced 22 useful mechanisms from 1000 task sets. An example of the design of a steering linkage is presented. A video of this linkage can be seen at http://www.youtube.com/watch?v=hEvbDiyQMiw.