US Patent 9156394 Suspension system for autonomous transports

An autonomous transport robot for transporting a payload, the autonomous transport robot including a drive section assembly having at least one motor and a pair of drive wheels coupled to the motor, a frame configured to support a payload, a transfer arm connected to the frame and configured for the autonomous transfer of payload to and from the frame, and a suspension system movably connecting the drive section assembly and the frame allowing relative movement between the frame and the drive section assembly.