Feed forward terms based on continuous model

Patent metadata

Field	Value
Publication number	US-9927794-B2
Application number	US-201515546943-A
Country	US
Kind code	B2
Filing date	Apr 2, 2015
Priority date	Apr 2, 2015
Publication date	Mar 27, 2018
Grant date	Mar 27, 2018

Abstract

An example method for controlling a carriage of a printing device is described. In one implementation, a target velocity value that satisfies a sharpness threshold is filtered by a processor resource of the printing device, a feed forward term is generated using a continuous model applied to the filtered velocity input using a plurality of electromechanical parameters, a feedback term is generated based on a difference between an expected pulse-width modulation (PWM) profile and an actual PWM profile, and a voltage to be provided to a motor of the carriage is adjusted based on the feed forward term and the feedback term.

First claim

What is claimed is:

1. A system comprising:
a filter engine to apply a filter to a target velocity value associated with a carriage, the filter including a filter parameter to round a state transition by changing the target velocity value from a first velocity value to a second velocity value when a first difference between the first velocity value and the second velocity value achieves a sharpness threshold;
a feed forward engine to determine a feed forward term of a carriage based on a continuous model that uses a target velocity value of the velocity profile, a mass of a device conveyable by the carriage, and a friction force expected against the carriage;
a feedback engine to determine a feedback term based on a second difference between the target velocity value and an actual velocity value of the carriage; and
a motion engine to cause the carriage to move based on the feed forward term and the feedback term.

2. The system of claim 1 , wherein:
the motion engine comprises a proportional controller that controls the motor using a pulse-width modulation (PWM) functionality that calculates a motor voltage based on the feed forward term and the feedback term, the feed forward term to be a PWM value of a target PWM profile; and
the filter engine is to:
identify the state transition of the velocity profile; and
modify the velocity profile at an area of the state transition to adjust to a class of the state transition and a velocity change at the state transition based on a filter parameter.

3. The system of claim 1 , wherein the feed forward engine is further to:
obtain the mass and the friction force via calibration of the device on the carriage; and
estimate an internal temperature based on a real-time thermal model using environment data, the actual velocity value, and an actual motor PWM value,
wherein the continuous model uses a plurality of motor parameters.

4. The system of claim 3 , wherein the feed forward engine is further to:
obtain the environment data using an ambient temperature sensor; and
modify the plurality of motor parameters based on the internal temperature,
wherein the plurality of motor parameters comprises a winding resistance and a torque constant.

5. The system of claim 3 , wherein the feed forward engine is further to:
determine the mass of the device using a print fluid level estimator based on a number of fired drops,
wherein the carriage is a printing device carriage and the device is a printing device pen.

6. An apparatus comprising:
a carriage;
a marking device coupled to the carriage;
a motor operatively coupled to the carriage; and
a controller comprising a processor resource and a computer-readable storage medium comprising a set of instructions executable by the processor resource to:
filter a target velocity value based on a filter parameter;
calculate a feed forward term comprising a pulse-width modulation (PWM) value associated with an expected velocity of a continuous model using the filtered target velocity value based on a mass of the marking device, a friction force expected by the carriage, and a motor parameter; and
cause the motor to move the carriage based on the PWM value.

7. The apparatus of claim 6 , further comprising:
a pen-ambient temperature sensor to obtain environmental data within the apparatus; and
wherein the set of instructions is executable by the processor resource to:
calculate a temperature estimate of the motor based on the environmental data.

8. The apparatus of claim 6 , further comprising:
a marking material level estimator coupled to the marking device, the marking material level estimator to count a number of drops fired by the marking device.

9. The apparatus of claim 6 , wherein the set of instructions to filter the digital model of the target velocity value is executable by the processor resource to:
identify a transition event associated with the target velocity value; and
dampen a change in velocity at a profile area of the transition event.

10. The apparatus of claim 6 , wherein the set of instructions is executable by the processor resource to:
compensate the PWM value for unmodelled dynamic, estimation errors, and non-linearities of an actual velocity of the carriage in comparison to the expected velocity.

11. A method for controlling a carriage of a printing device comprising:
receiving a target velocity value via a driver interface of the printing device based on a carriage move request;
filtering, by a processor resource of the printing device, the target velocity value identified as within a state transition of a velocity profile that satisfies a sharpness threshold;
generating, by the processor resource, a feed forward term based on a continuous model that uses the filtered target velocity value and a plurality of electromechanical parameters identifiable at calibration;
generating, by the processor resource, a feedback term based on a difference between an expected pulse-width modulation (PWM) profile of a carriage and an actual PWM profile of the carriage; and
adjusting a voltage to be provided to a motor to move the carriage based on the feed forward term and the feedback term.

12. The method of claim 11 , wherein:
filtering the target velocity value comprises:
dampening the state transition to satisfy at least one of an excitation threshold and an acoustic threshold.

13. The method of claim 11 , comprising:
calibrating a marking device coupled to the carriage; and
identifying the mass parameter and the friction parameter at a time of calibration,
wherein the plurality of electromechanical parameters comprise the mass parameter, the friction parameter, and a motor parameter.

14. The method of claim 13 , comprising:
determining an amount of marking material used by the marking device;
estimating a marking material level of the marking device based on the amount of marking material used and a material capacity of the marking device; and
calculating the mass parameter based on the marking material level of the marking device.

15. The method of claim 11 , comprising:
estimating an internal temperature of the motor using a real-time thermal model with input from an ambient temperature sensor.

Assignees

• Hewlett Packard Development Co

Inventors

• Ewe Michael

Classifications

• G05B2219/45187

  Printer · CPC title

• G05B2219/41437

  Feedforward of speed · CPC title

• G05B19/23 Primary

  for point-to-point control · CPC title

• B33Y50/02 Primary

  for controlling or regulating additive manufacturing processes · CPC title

• B41J25/001

  Mechanisms for bodily moving print heads or carriages parallel to the paper surface · CPC title