Abstract: A storage and retrieval machine has a telescopically extendible shuttle assembly and having spring tensioned shuttle idler pulleys for the slave drive members, preferably chains, of the shuttle assembly. A spring, preferably a die spring, exerts a biasing force on each idler pulley which opposes forces imposed on the idler pulley by the corresponding slave chain. Pre-tensioning the idler pulley in this manner assures adequate tension on the slave chain to prevent or at least inhibit undulations in plate movement which otherwise could occur during telescopic extension and retraction of the shuttle assembly if the slave chain were inadequately tensioned. Use of the spring loaded idler pulley also obviates the need to over-tension the slave chain and prevents or inhibits premature wear and failure of the idler pulley, pulley bearing, and/or chain.

Abstract: A communication system for a storage and retrieval machine comprises a conductor bar, base and carriage electrical devices, a sliding brush, first and second transmitters, and first and second receivers. The sliding brush is mounted to the carriage and is in slidable electrical contact with the conductor bar. The transmitters and receivers are coupled to the conductor bar or the sliding brush, depending on the direction of transmission. The first and second transmitters transmit positive half-waves and negative half-waves, respectively, across the conductor bar in response to inputs. Hence, two one-bit intra SRM communication links are provided between the SRM carriage and base. A communication system for communicating high priority and low priority messages between a base and carriage of an SRM comprises base and carriage electrical devices, and first and second communication links.

Abstract: A storage and retrieval machine comprises a base, a carriage, and a control system. The control system is used to control the movement of the carriage in the vertical direction and/or the movement of the base in the horizontal direction. The control system includes at least one encoder and at least one optical distance meter. The encoder provides relative position information during a middle portion of the SRM trajectory, i.e., during the implementation of a feedback control scheme. The optical distance meter provides absolute position information to the control system at an endpoint of the SRM trajectory, i.e., to verify that the SRM has in fact reached its destination. If the control system controls both the movement of the carriage and the movement of the base, then two encoders and two optical distance meters are used.

Abstract: A method of mapping a warehouse rack structure having a plurality of racks comprises the steps of creating a logical matrix and updating the logical matrix. The updating step further includes the steps of causing a moveable device to travel to a first one of the plurality of racks, and producing a first machine-readable distance measurement output. The machine-readable distance measurement output is produced using a first sensor and represents a distance between the first sensor and a first position on the warehouse rack structure. A system for mapping a warehouse rack structure comprises a storage and retrieval machine; a rack structure; a logical matrix; and a computer. The storage and retrieval machine has first and second ultrasonic sensors mounted thereon. The rack structure includes a plurality of racks. The logical matrix stores horizontal position information and vertical position information for each of the plurality of racks.