A mobile robot comprising: a robot body having a forward drive direction; a drive system supporting the robot body above a floor surface for maneuvering the robot across the floor surface; a main circuit board in communication with the drive system; a bumper frame defining a shape complementary of a front periphery of the robot body, the bumper frame supported by the robot body; and an obstacle sensor system disposed on the bumper frame, the obstacle sensor system comprising: a multiplexing auxiliary circuit board supported by the bumper frame, the auxiliary circuit board including a computing processor and non-transitory memory, the computing processor capable of executing instructions stored on the memory; an array of proximity sensors (410, 420) distributed along the bumper frame, each proximity sensor (410, 420) having at least two wires collected in at least one wire collector, the at least one wire collector connected to the auxiliary circuit board; and a communication line connecting the auxiliary circuit board to the main circuit board, the communication line having fewer than half the wires connecting the array of proximity sensors (410, 420) to the auxiliary circuit board; wherein the auxiliary circuit board is configured to: receive, at the computing processor, sensor signals from the array of proximity sensors (410, 420); process the received sensor signals using the computing processor; package the processed sensor signals into a data packet recognizable by the main circuit board; and send the data packet from the computing processor to the main circuit board. a robot body having a forward drive direction; a drive system supporting the robot body above a floor surface for maneuvering the robot across the floor surface; a main circuit board in communication with the drive system; a bumper frame defining a shape complementary of a front periphery of the robot body, the bumper frame supported by the robot body; and an obstacle sensor system disposed on the bumper frame, the obstacle sensor system comprising: a multiplexing auxiliary circuit board supported by the bumper frame, the auxiliary circuit board including a computing processor and non-transitory memory, the computing processor capable of executing instructions stored on the memory; an array of proximity sensors (410, 420) distributed along the bumper frame, each proximity sensor (410, 420) having at least two wires collected in at least one wire collector, the at least one wire collector connected to the auxiliary circuit board; and a communication line connecting the auxiliary circuit board to the main circuit board, the communication line having fewer than half the wires connecting the array of proximity sensors (410, 420) to the auxiliary circuit board; wherein the auxiliary circuit board is configured to: receive, at the computing processor, sensor signals from the array of proximity sensors (410, 420); process the received sensor signals using the computing processor; package the processed sensor signals into a data packet recognizable by the main circuit board; and send the data packet from the computing processor to the main circuit board. a multiplexing auxiliary circuit board supported by the bumper frame, the auxiliary circuit board including a computing processor and non-transitory memory, the computing processor capable of executing instructions stored on the memory; an array of proximity sensors (410, 420) distributed along the bumper frame, each proximity sensor (410, 420) having at least two wires collected in at least one wire collector, the at least one wire collector connected to the auxiliary circuit board; and a communication line connecting the auxiliary circuit board to the main circuit board, the communication line having fewer than half the wires connecting the array of proximity sensors (410, 420) to the auxiliary circuit board; wherein the auxiliary circuit board is configured to: receive, at the computing processor, sensor signals from the array of proximity sensors (410, 420); process the received sensor signals using the computing processor; package the processed sensor signals into a data packet recognizable by the main circuit board; and send the data packet from the computing processor to the main circuit board. receive, at the computing processor, sensor signals from the array of proximity sensors (410, 420); process the received sensor signals using the computing processor; package the processed sensor signals into a data packet recognizable by the main circuit board; and send the data packet from the computing processor to the main circuit board.