Movable storage unit control system

A storage system comprising

• a plurality of movable storage units,
• reversible motor means mounted to said movable units, respectively, for driving each unit selectively in one direction or the opposite direction to open an aisle between a pair of said units,
• motor control circuit means for each unit connected to said motor means on the unit,
• controller means including processor means on the units, respectively, and conductors interconnecting said controller means,
• start switch means on each unit for selecting opening of an adjacent aisle, said start switch means connected to said interconnected controller means on the same unit and manually operable to activate one of said processor means in said controller means to produce command signals to which the processor means in at least one other controller means responds by providing command signals to said motor control circuit means for causing said circuit means to turn on one or more motor means for driving one or more units in directions that result in opening the selected aisle,
• tape switch means mounted to at least one side of each of said movable units and extending over substantially the length of the unit, said tape switch means comprising an elongated support composed of flexible insulating material and elongated conductive strips constituting switch contacts mounted to said support in spaced relation to provide normally open switch contacts,
• test circuit means for conducting test pulses that are caused to be generated by said processor means at a predetermined frequency back to said processor means, said test circuit means including test circuit switch means, said processor means responding to said test circuit switch means becoming nonconducting so as to interrupt said pulses by commanding said motor control circuit means to deactive said motor means to stop movement of the unit,
• safety sweep bar means mounted to the sides of said movable storage units and a plurality of normally closed safety sweep switches arranged for being opened in response to said bar means encountering an obstruction when the unit on which said bar means is mounted is moving,
• said safety sweep switches being connected in series with each other in said test circuit means so that if any sweep switch opens said test pulses applied to said sweep switches will not return to said processor means,
• one pair of corresponding ends of said strips in said tape switch means being connectable to an electric power source and a circuit loop connected across the other pair of corresponding ends, said circuit loop including optoisolator means for controlling said test circuit switch means in said test circuit means during a safety sweep test pulse so that said test circuit switch means remains conducting as long as said loop is conducting and becomes nonconducting when said contacts in said tape switch are in contact and said loop is short circuited and nonconducting, said optoisolator having the light emitting diode thereof connected in said circuit loop and the photosensitive transistor thereof connected in said test circuit means.