System and method for dual stage control of field printer robot

A system, comprising:

• a mobile printing robot configured to print a layout at a construction site;
• a differential drive to move the mobile printing robot;
• a printing system including a movable print carriage and a linear actuator to move a print head, having at least one printer, laterally with respect to a fore-aft axis of motion of the mobile printing robot;
• and
• a dual-stage dual input, single output (DISO) controller of the mobile printing robot having a combined two stage control system to control a pen position in a print mode associated with a selected printer, including:
• 1) a first control stage to control steering of the mobile printing robot and control its velocity;
• 2) a second control stage to control a position of the linear actuator;
• a pen position associated with an active printer being a sum of the lateral position of the print head relative to a reference point of the robot determined by the steering of the mobile printing robot, the first control stage being a slower control stage than the second control stage;
• and
• the controller including a decoupling filter to filter the output of the first control stage by an approximation of the inverse of the second control stage and subtracting the result from a reference input to the second control stage such that the decoupling filter causes the combined two-stage control system to approximate closed-loop dynamics of the second control stage.

A dual input, single output (DISO) controller for a mobile printing robot, comprising:

• a first control stage to control steering and velocity of a differential drive of the mobile printing robot;
• a second control stage to control a linear actuator, to control lateral movement with respect to a fore-aft axis, of a movable print head having at least one printer to print a layout on a construction surface;
• the first control stage being a slower stage than the second control stage;
• movement of the faster second control stage being measured relative to the first control stage, enable closed loop control of the second control stage independently of the slower first control stage;
• and
• a decoupling filter decoupling the dynamics of the first control stage and the second control stage by filtering an output of the first control stage by an approximate inverse of the closed-loop dynamics of the second control stage and subtracting the result from a reference input to the control the second control stage.

A method of operating a mobile printing robot, comprising:

• monitoring a position of the mobile printing robot;
• in a print mode, coordinating a position of a printer of a print head, using a dual-stage dual input, single output (DISO) controller having a first control stage to control differential steering of a differential drive of the mobile printing robot and a second control stage to control a linear actuator used to control a lateral position of a movable print head of the mobile printing robot with respect to a fore-aft axis;
• using a decoupling filter to reduce deleterious interactions between the first control stage and the second control stage;
• and
• in a print mode, performing at least one phase of a printing process for a line of a construction layout.