Mobile printers

A mobile printer, comprising:

• an ultrasound sensor to sense a set of ultrasonically-sensed positional data points of a print nozzle as the mobile printer is moved a direction across a printing surface;
• a plurality of optical sensors to sense a set of optically-sensed positional data points of the print nozzle when the mobile printer is moved the direction across the printing surface;
• a motion sensor;
• and
• a processor to:
• receive a print request from a computing device;
• determine an offset between the print nozzle and the plurality of optical sensors;
• apply a calibration function, according to the offset, on the set of ultrasonically-sensed positional data points, the set of optically-sensed positional data points, and information received from the motion sensor corresponding to a motion of the printer to provide a set of corrected positional data points of the print nozzle of the printer;
• cause the print nozzle to deposit ink according to a print request and to the set of corrected positional data points;
• identify information from the motion sensor about a reversal of the direction across the printing surface;
• compensate for a first time lag caused by the reversal of the direction based on a position and a speed of the printer included in the identified information about the reversal of the direction;
• and
• supplement the set of ultrasonically-sensed positional data points with the identified information about the reversal of the direction in response to receiving a notification from the motion sensor about the reversal of the direction, wherein the notification prevents printing errors by increasing an accuracy of the set of corrected positional data points.

A method of printing, comprising:

• receiving a print request;
• collecting a set of ultrasonically-sensed positional data points of a print nozzle as the mobile printer is moved a direction across a printing surface;
• collecting a set of optically-sensed positional data points of the print nozzle when the mobile printer is moved the direction across the printing surface;
• collecting information corresponding to a motion of the printer from a motion sensor;
• applying a correction function on the set of ultrasonically-sensed positional data points, the set of optically-sensed positional data points, and the information corresponding to the motion of the printer to provide a set of corrected positional data points of the print nozzle;
• depositing ink according to the print request and the set of corrected positional data points;
• identifying information from the motion sensor about a reversal of the direction across the printing surface;
• compensating for a first time lag caused by the reversal of the direction based on a position and a speed of the printer included in the identified information about the reversal of the direction;
• and
• supplementing the set of ultrasonically-sensed positional data points with the identified information about the reversal of the direction in response to receiving a notification from the motion sensor about the reversal of the direction, wherein the notification prevents printing errors by increasing an accuracy of the set of corrected positional data points.