Accurate volume dispensing using pump and flow sensor

A system of controlling a positive displacement pump, comprising:

• the positive displacement pump configured to pump a fluid through a tube;
• a flow sensor configured to measure a flow rate of the fluid in the tube downstream from the positive displacement pump;
• and
• a pump controller configured to:
• run a calibration procedure to determine a mapping between a pump speed and a flow rate for a current configuration of the positive displacement pump, a tubing size, and a fluid characteristic;
• determine a pump motion profile based on the mapping, wherein the pump motion profile includes an acceleration phase, a constant speed phase, and a deceleration phase such that a total volume pumped according to the pump motion profile and the mapping is equal to a target volume;
• run the positive displacement pump according to the pump motion profile;
• measure a constant flow rate at a downstream flow rate sensor while the pump operates at a first constant speed during the constant speed phase;
• determine an adjustment to the pump motion profile based on the constant flow rate, the adjustment including a second constant speed;
• run the positive displacement pump at the second constant speed;
• and
• decelerate the positive displacement pump according to the adjusted pump motion profile until the target volume is dispensed.

A positive displacement pump, comprising:

• a pumphead configured to pump a fluid through a tube;
• a flow sensor configured to measure a flow rate of the fluid in the tube downstream from the pumphead;
• and
• a pump controller configured to:
• run a calibration procedure to determine a mapping between a pump speed and a flow rate for a current configuration of the positive displacement pump, a tubing size, and a fluid characteristic;
• determine a pump motion profile based on the mapping, wherein the pump motion profile includes an acceleration phase, a constant speed phase, and a deceleration phase such that a total volume pumped according to the pump motion profile and the mapping is equal to a target volume;
• run the positive displacement pump according to the pump motion profile;
• measure a constant flow rate at a downstream flow rate sensor while the pump operates at a first constant speed during the constant speed phase;
• determine an adjustment to the pump motion profile based on the constant flow rate, the adjustment including a second constant speed;
• run the positive displacement pump at the second constant speed;
• and
• decelerate the positive displacement pump according to the adjusted pump motion profile until the target volume is dispensed.