A stationary robotic base carries a movable robotic platform and supports a pair of vertical striker plates spaced apart by a central, elastomeric block. The striker plates are confined within a compartment of the stationary base, and extend upward into a pathway defined by a lug depending from the moving platform. The lug contacts the top portion of a given striker plate and, as the plate is struck, it tends to pivot about its bottom edge toward the other plate, compressing the elastomeric block, while the other plate is held from moving away from the block. The assembly is bidirectional, with each striker plate being yieldable toward the other as it is encountered by the moving lug. In the event that the moving element possesses more energy than the maximum stopping energy of the elastomeric block, the first encountered striker plate will pivot to such position that the lug will overtravel the striker plate and pass over the elastomeric block until it comes to rest against the stationary, nonpivoting striker plate.