WO2015116137A1

WO2015116137A1 - Identifying conditions based on motor measurements

Info

Publication number: WO2015116137A1
Application number: PCT/US2014/014031
Authority: WO
Inventors: Bhishma HERNANDEZ MARTINEZ; Emilio LOPEZ MATOS; Fernando BAYONA ALCOLEA
Original assignee: Hewlett-Packard Development Company, L.P.
Priority date: 2014-01-31
Filing date: 2014-01-31
Publication date: 2015-08-06

Abstract

An example device in accordance with an aspect of the present disclosure includes a drive circuit, a voltage circuit, a first current circuit, a second current circuit, and a controller. The drive circuit is to drive a motor. The voltage circuit is to identify a motor voltage measurement. The first current circuit is to identify a first motor current measurement. The second current circuit is to identify a second motor current measurement. The controller is to identify a condition based on the measurements, and provide a notification corresponding to the condition.

Description

IDENTIFYING CONDITIONS BASED ON MOTOR

MEASUREMENTS

BACKGROUND

[0001] A printer may have various mechatronics systems for handling different printing aspects, which have become more and more complex over time. The mechatronics systems can malfunction due to shocks experienced by the printer during its lifetime, failure of a subassembly associated with a mechatronic system, disconnections of connector cables, and other malfunctions. Such breakdowns can be time-consuming and costly to repair.

BRIEF DESCRIPTION OF THE DRAWINGS/FIGURES

[0002] FIG. 1 is a block diagram of a device including a first current circuit, a second current circuit, and a voltage circuit according to an example.

[0003] FIG. 2 is a block diagram of a device including a first current circuit, a second current circuit, and a voltage circuit according to an example.

[0004] FIG. 3 is a flow chart based on identifying a failure mode according to an example.

[0005] FIG. 4 is a flow chart based on providing a notification according to an example.

DETAILED DESCRIPTION

[0006] Example devices provided herein can identify whether subsystems of the devices are properly connected and operable, or malfunctioning. Recognizing subsystem behavior enables example devices to produce specific notifications regarding a condition of the devices, such as a failure mode message addressing ways to resolve the issue quickly and affordably. Accordingly, devices may enjoy early failure detection and reduced need for technical support, for continued productivity.

[0007] In an example, a printer includes various circuits to sense parameters of mechatronics, and a routine to identify whether those parameters are acceptable, and predict whether a condition is met and a notification should be issued. Device architecture may include redundant topology, enabling an ability to recognize self-failures. Notifications may advise what specific mechanical and mechatronic parts are involved in a problem issue, and whether the issue involves a permanent or intermittent failure mode, avoiding a need for a separate/abstract investigation of the system error. A printer test may be performed at any time an unexpected behavior is encountered (or automatically detected) in a motor or mechatronics circuit. A notification may be provided, having clear and informative failure information for recognizing parts to service or replace, minimizing repair downtime and costs.

[0008] FIG. 1 is a block diagram of a device 100 including a first current circuit 120, a second current circuit 130, and a voltage circuit 1 10 according to an example. Drive circuit 104 is to drive the motor 102. The voltage circuit 1 10 is to identify a motor voltage 1 12, the first current circuit 120 is to identify a first motor current 122, and the second current circuit 130 is to identify a second motor current 132. The controller 140 is to identify a condition 142 of the device 100, based on the motor voltage 1 12, the first motor current 122, and the second motor current 132. The controller 140 may provide a notification 144 based on the condition 142.

[0009] Drive circuit 104 is to drive motor 102, e.g., based on providing a voltage and current to the motor 102. Motor 102 may include various types of motors, and may include motors specific to printers. In an example, motor 102 may be a carriage motor, a paper load motor, a paper advance motor, etc.

[0010] The various circuits 1 10, 120, 130 are capable of measuring voltage and current associated with the motor 102, in both rotation directions, whether the motor 102 is working like a generator or a motor (e.g., being powered). Furthermore, the circuits may provide redundant measurements, enabling the controller 140 to check whether the redundant measurements are inconsistent.

[0011] The voltage circuit 1 10 can measure motor voltage 1 12 at the leads of the motor 102. The motor voltage 1 12 is taken in parallel with the motor 102, independent of the other circuits and their measured currents. The voltage circuit 1 10 may measure the motor voltage 1 12 in both rotation directions of the motor 102, and also whether the motor 102 is working like a generator (braking) or a motor. The independence of the voltage circuit 1 10 measurement from the first or second current circuits 120, 130, enables the controller 140 to observe additional characteristics of the motor 102, such as when the motor voltage 1 12 and the motor currents transition from having the same sign (both being positive or negative) to having different signs, that might not be observable if the first or second current measurements were derived from the voltage measurement (or vice versa), in contrast to being independently measured.

[0012] Motor current may be measured by two independent circuits. The first current circuit 120 is to identify the first motor current measurement 122, and the second current circuit 130 is to identify the second motor current measurement 132. The motor current is measured in both rotation directions, and when the motor is working like a generator (braking) or motor. The first motor current measurement 122 and the second motor current measurement 132 are independent of each other, enabling two different approaches to measuring motor current, and redundancy self-checking between the two currents. Furthermore, the controller 140 may compare the motor voltage 1 12 measurement, based on a conversion between voltage and current, for further redundancy cross-comparisons.

[0013] Additional measurements may be performed, e.g., mechanically checking for movement of motor 102 based on an encoder (not shown in FIG. 1 ) to monitor the rotational position of the motor 102.

[0014] The controller 140 may recognize conditions, such as a failure mode, by determining motor voltage measurements 1 12 and motor current measurements 122, 132, and comparing the identified conditions with the expected conditions. An expected condition may be based on relationships between the different measurements, including between the same measurement over time (e.g., comparing to an earlier version of the measurement that may be stored and compared against).

[0015] The first current circuit 120 may obtain the first motor current measurement 122 from an output of the drive circuit 104. The second current circuit 130 may obtain the second motor current measurement 132 directly from the motor 102, from within the drive circuit 104. Accordingly, the second current circuit 130 has the opportunity to obtain a more precise and accurate measurement by virtue of its direct series connection to the motor 102, and may use correspondingly more precise and accurate measurement components compared to other components of the device 100. The first current circuit 120, in contrast, is measuring the current of the motor 102 based on a coupling via the drive circuit 104. Accordingly, the first current circuit 120 does not need the same level of accuracy and precision as the second current circuit 130, enabling the use of lower-cost measurement circuitry compared to the second current circuit while still providing information enabling the controller 140 to determine if components are in proper working order (e.g., based on the redundancy between measurements, within an error tolerance).

[0016] The controller 140 may compare measurements to determine whether the measurements are consistent with each other. In an example, the controller 140 may expect to see a value for the motor voltage measurement 1 12 sensed by the voltage circuit 1 10, that should roughly correspond with the voltage of the driving signal applied by the drive circuit 104 (e.g., a value expressed in units of pulse-width modulation (PWM)). The controller 140 may determine that an expected voltage in the drive circuit 104 should be V1 , for example (V1 corresponding to a driving circuit voltage as shown being applied to an H-bridge driving circuit in FIG. 2). The controller 140 may observe and/or control the output of the drive circuit 140, to expect the voltage V1 produced by PWM. The controller 140 thus may compare the observed measurement of the motor voltage 1 12, with the expected voltage. The controller 140 may have an error tolerance, e.g., within +-10%, for evaluating the consistencies between expected and observed measurements. A similar approach may be applied to the current circuits 120, 130. The controller 140 may have a table of expected values for various parameters to be measured. Furthermore, the controller 140 may directly compare one measured value to another measured value, without using a stored table of values. The controller 140 may populate a table of stored values, based on values that have been observed/measured in the past. Based on the degree of matching or mismatching/inconsistency between parameters, the controller 140 may determine that a condition 142 exists, and provide a corresponding notification 144.

[0017] In an example, the controller 140 may expect a measured current to be within a range between 5/6 amps and 2 amps, and identify a condition 142 if the measured current is outside of that range. Similarly, the controller 140 may determine that no voltage is being applied by the drive circuit 104 such that there should be no voltage at the leads of the motor 102. However, if the motor voltage measurement 1 12 indicates a measurable voltage under these conditions, the controller 140 may identify that a condition 142 exists.

[0018] The notification 144 may be provided at the device 100, e.g., on a display screen coupled to controller 140. The notification 144 also may be delivered via other techniques, such as an email notification, a network notification, and instant message, or other technique for communicating information from the device 100 to an operator.

[0019] Thus, device 100 provides multiple different options to measure motor currents. If a component fails for some reason (e.g., the motor 102 fails), or is not connected or working improperly, the built-in redundancy of device 100 provides advantages of robustness and reliability. It is possible to have the system identify whether one or more of the components are problematic. It is also possible to identify if the system itself is problematic. In an example, device 100 has the capability to detect a short circuit in the motor cable that goes from the motor 102 to a main logic board of the printer. Accordingly, the controller 140 may identify what component needs to be serviced, and whether the issue is due to the measurement system itself, or one of the components/systems. Thus, the controller 140 may identify when a condition 142 has arisen, and identify a failure mode directly, to identify exactly which part is to be replaced, and identify which part (e.g., via notification 144) needs servicing.

[0020] FIG. 2 is a block diagram of a printer device 200 including a first current circuit 220, a second current circuit 230, and a voltage circuit 210 according to an example. A drive circuit 204 is to drive the motor 202. An encoder 206 is coupled to the motor 202 to monitor a status of the motor 202. The voltage circuit 210 is to identify a motor voltage, and includes a voltage divider 214. A voltage analog-to-digital converter 250 (ADC3) couples output from the voltage circuit 210 to the controller 240. The first current circuit 220 is to identify a first motor current measurement, and includes a first shunt resistor 224, first amplifier 226, and first filter 228. A first current analog-to-digital converter 250 (ADC1 ) couples output from the first current circuit 220 to the controller 240. A second current circuit 230 is to identify a second motor current measurement, and includes a second shunt resistor 234, a second amplifier 236, a voltage reference 237, and a second filter 238. A second current analog- to-digital converter 252 (ADC2) couples output from the second current circuit 230 to the controller 240. The controller 240 is coupled to memory 260, and is to identify a printer condition 242 of the device 200, based on output from the voltage circuit 210, the first current circuit 220, the second current circuit 230, and the encoder 206. The controller 240 may provide a notification 244, based on the printer condition 242.

[0021] The device 200 enables multiple different ways to obtain measurements, or otherwise identify expected operational parameters (e.g., +V1 ; values stored in memory 260, etc.). This redundant topology enables feedback between measurements/values to identify a failure mode, including a mix of failure modes. For example, motor voltage may be measured, along with two different motor current measurements. Additionally, the encoder 206 (e.g., an analog encoder) may provide the motor position (corresponding to a printer carriage position, for example) and motor movement. These four values can be used by the controller 240 to establish what part of the control loop of device 200 is failing. For example, if both motor current measurements agree with each other, and the motor voltage measurement is consistent with the applied voltage (and corresponds with the measured motor currents), but the encoder value is inconsistent, the controller 240 can determine that the encoder 206 is failing because it is the outlier. Device 200 also may reliably identify situations where multiple measurements are seemingly consistent, but do not indicate a correct situation. For example, the encoder 206 may show that the motor 202 is turning, but the voltage measurement fails, and the first and second current measurements fail. In such a situation, the controller 240 may determine that there is a problem involving a component that is affecting all three measurements: that a failure occurred to a main circuit board handling the measurement circuits. Accordingly, even in situations where one element (e.g., the encoder 206 to detect rotation of the motor) is inconsistent with multiple other elements, the controller 240 can intelligently identify a printer condition 242 where the main board is faulty, and not the motor 202 or the encoder 206 in that example. The controller 240 may generate an appropriate notification 244, with detailed analysis and specific instructions to replace the main board while retaining the other components. Accordingly, device 200 enables servicing of the device 200 with efficiency and minimized down-time due to not needing to diagnose the problem. In another example, the topology and interaction of the voltage circuit 210, the first current circuit 220, and the second current circuit 230 enables diagnosis of a faulty drive circuit 204 (shown as an H-bridge). The voltage circuit 210 and second current circuit 230 are coupled to monitor conditions in the drive circuit 204, based on coupling to a mid-section of the drive circuit 204 (between switches). In contrast, the first current circuit 220 is coupled to the outside of the drive circuit 204. Accordingly, if at least some of the switches of the drive circuit 204 are malfunctioning, an inconsistency may appear between the current circuits 220, 230, and the voltage circuit 210. More specifically, a situation may cause the first current circuit 220 to show a high current (e.g., due to acting as a pathway for the drive current from the drive circuit 204), in contrast to the second current circuit 230 showing low current and the voltage circuit 210 showing low voltage. Thus, the redundancy and arrangement among the circuits enables the controller 240 to recognize that the printer device 200 is suffering a faulty drive circuit 204 printer condition 242, and provide a notification 244 to replace, enabling valuable diagnostic analysis.

[0022] The motor 202 also may be subject to problem conditions, which the controller 240 may diagnose as a printer condition 242 and provide a notification 244. For example, the various circuits may detect a short circuit in a motor cable that couples the motor 202 to the main board/H-bridge drive circuit 204.

[0023] The encoder 206 may be generic, analog, digital, or may be other forms of encoders. The encoder 206 may have a very high accuracy, because it can be used to position the printer carriage very accurately for ink placement. Thus, the encoder 206 may be a relatively reliable indicator if it is reporting motor rotations, even if other elements report zero current/voltage (which may indicate that the main board is faulty and the encoder is not faulty). However, the encoder 206 may be diagnosed as faulty based on, e.g., the other circuits indicating that the motor 202 is operating normally, while the encoder 206 shows no motor movement or other signs of inconsistency. The controller 240 may identify what number of encoder counts may correspond to a given voltage or current, and therefore factor the relationship into determining whether results are consistent between different components of device 200. Although shown as a separate component, in an alternate examples, the encoder 206 may be incorporated into the motor 202.

[0024] The voltage circuit 210 is to identify the motor voltage at the leads of the motor 202, based on a parallel coupling to the motor 202, by means of two combined voltage dividers 214. Output from the voltage circuit 210 is passed to the controller 240 via ADC3 254, which may be embedded into a microcontroller from an Application Specific Integrated Circuit (ASIC) or other ADC source.

[0025] The first current circuit 220 is to identify current on a "low side" of the drive circuit 204, flowing through the motor windings by means of a first shunt resistor 224 and a relatively low cost first amplifier 226 (e.g., as compared to the second amplifier 236). The first amplifier 226 is to measure the voltage drop across the first shunt resistor 224, arranged in series with the H-bridge drive circuit 204, and passed via filter 228 and ADC1 250 to the controller 240. The ADC1 250 is distinct from the ADC3 254 associated with the voltage circuit 210, as each voltage/current circuit is associated with its own ADC.

[0026] The first shunt resistor 224 of the first current circuit 220 is connected in series with the H-bridge. The first shunt resistor 224 may have a very low resistance (approximately milliohms) and high accuracy (approximately 1 %). The first current circuit 220 is to measure the current that passing through the h- bridge and going through the motor 202. The first current circuit 220 is coupled in series with the H-bridge 204. Accordingly, the first current circuit 220 may provide information about a status of the H-bridge 204 and motor 202. The first amplifier 226 may be used to measure a magnitude of bidirectional current, and the controller 240 may identify a motor direction corresponding to the direction of the bidirectional current at first amplifier 226. When the motor 202 is not running (0 amps) output of the first amplifier 226 is 0 volts. Thus, although the first amplifier 226 is relatively inexpensive and without relatively high accuracy, the first current circuit 220 fully enables auto-recognition of various failure modes, based on the redundancy of information obtained, as well as the particular arrangement between the various components of device 200. Although a particular type of first current circuit 220 is shown, alternate examples may use other topologies for current sensors.

[0027] The drive circuit 204 is coupled to the second current circuit 230. The drive circuit 204 includes an H-bridge for driving the motor 202 in either rotational direction (clockwise, counterclockwise). The H-bridge is powered from a high voltage rail V1 (in general V1 » V2), where V2 is a power supply voltage rail for logic control. Typical values are V1 = 42 volts, V2 = 5 volts. The H-bridge contains four switches, which may be transistors (e.g., metal-oxide- semiconductor field-effect transistor (MOSFET) driven by pulse-width modulated (PWM) signals generated by controller 240.

[0028] The second current circuit 230 may be referred to as a high side circuit. A second motor current measurement is made, to identify motor current 202 flowing through the windings of the motor 202, based on second shunt resistor 234 and second amplifier 236, which may be provided as an instrumentation amplifier having a high Common Mode Rejection Ratio (CMRR). The current measurement of the second current circuit 230 is taken in series with windings of the motor 202, and passed to the controller 240 via ADC2 252. ADC2 252 is again separate from either ADC1 250 and ADC3 254. The second shunt resistor 234 has a very low resistance (around milliohms) and high accuracy (typically 1 %), to measure all current flowing through the motor 202 (in both rotational directions, and whether the motor 202 is working like a generator associated with braking (broadly known as 'back EMF'), or a motor. The second current circuit 230 may provide information about operational conditions of the motor 202, such as the value of the motor current passing through the motor 202. In an example, the first current circuit 220 and the second current circuit 230 should indicate the same current value, within an error tolerance. However, mismatching values/figures may indicate an issue.

[0029] The second amplifier 236 may measure bidirectional current based on voltage reference 237, which may be chosen as V2/2. The voltage reference 237 is tied to an offset input of the second amplifier 236. When the motor 202 is not running (0 amps), the output of the second amplifier 236 is half of the dynamic range (0 - V2 volts). For a power supply V2 = 5 volts, the offset is 2.5 volts. This offset may be generated by a stable voltage reference, with temperature compensation to avoid temperature deviation, and tolerance against V2 voltage drops.

[0030] Voltage drops at the first shunt resistor 224 and the second shunt resistor 234 are very low, and are to be amplified while rejecting circuit noise. Thus, the first and second amplifiers 226, 236, provide enough gain to adapt the voltages associated with the shunt resistors to a dynamic range of the ADCs. The second amplifier 236 may be a high CMRR instrumentation amplifier block supporting bidirectional current measurement, and having enough gain to adapt the voltage to the dynamic range of the ADC2 252.

[0031] The first and second filters 228, 238 are to reject high frequency noise, e.g., noise associated with PWM switching of the H-bridge switches. The filters 228, 238 may be active filters, and may be implemented by operational amplifier, in a Sallen-Key second-order topology. [0032] Referring to Figures 3 and 4, flow diagrams are illustrated in accordance with various examples of the present disclosure. The flow diagrams represent processes that may be utilized in conjunction with various systems and devices as discussed with reference to the preceding figures. While illustrated in a particular order, the disclosure is not intended to be so limited. Rather, it is expressly contemplated that various processes may occur in different orders and/or simultaneously with other processes than those illustrated.

[0033] FIG. 3 is a flow chart based on identifying a failure mode according to an example. Such identification may be performed at the time of a device startup, or while the device is servicing tasks, and may identify and add additional information regarding mechatronic status (e.g., by storing such information in device memory). In block 310, a motor is actuated in a first direction, based on a controller to control a drive circuit coupled to the motor. For example, a printer device may actuate a carriage motor, to slew a carriage in a first direction, based on a PWM signal having a first PWM sign (positive or negative). In block 320, a motor position is identified, based on an encoder coupled to the motor. For example, an accurate ink jet printer encoder may be used, associated with accurate and precise positioning of an inkjet carriage. In block 330, a motor voltage measurement is identified, based on a voltage circuit coupled in parallel with the motor. In an example, the voltage circuit includes a voltage divider to identify the motor voltage. In block 340, a first motor current measurement is identified, based on a first current circuit coupled in series with the drive circuit. In an example, the first current circuit is to identify the first motor current measurement independent of the motor voltage identified by the voltage circuit. In block 350, a second motor current measurement is identified, based on a second current circuit coupled in series with the motor. In an example, the second current circuit is coupled in series with a drive circuit that is to drive the motor. In block 360, a first inconsistency is checked for in the motor position, the motor voltage, the first motor current, and the second motor current. In an example, the first motor current and the second motor current are checked to see if they are within an error tolerance of each other. In block 370, the motor is actuated in a second direction opposite the first direction. In an example, a controller is to apply a PWM signal to the motor of a second sign (positive or negative) that is opposite the first sign described above with reference to actuating the motor in the first direction. In block 380, a second inconsistency is checked for in the motor position, the motor voltage, the first motor current, and the second motor current. In an example, the controller may check whether any parameters have newly become inconsistent since block 360, or whether they have remained inconsistent since the earlier check. In block 390, a failure mode, based on the first inconsistency and the second inconsistency, is identified. In an example, the failure mode may indicate which of various issues have been identified, to help expedite repair and minimize downtime.

[0034] As for identifying inconsistencies, a controller may consider whether checked values are misaligned with expected values, indicative of a failing part. The controller also may consider whether there is a high discordance between measurements (e.g., in either of blocks 360 and/or 380, considered alone or together). The controller may flag an issue, for example, if a first voltage value, e.g., 23 V, is being applied, but yet only 3 V is being measured, indicating a problem. Observing a high current may indicate that a motor is connected, but that something is not working properly coupled to the motor, e.g., at the main board to which the motor is coupled. The controller may identify an issue based on observing a discrepancy in redundant measurements, e.g., in the first/second current circuits. Such techniques enable the controller to distinguish and point directly to the issue that has been identified.

[0035] FIG. 4 is a flow chart based on providing a notification according to an example. Flow starts at block 410. In block 420, a motor is driven in a first direction. In block 430, measurements are identified, including a first motor current, a second motor current, a motor voltage, and an encoder count. In block 440, it is determined whether there is a first inconsistency. If not, flow proceeds to block 450. In block 450, a motor is driven in a second direction. In block 460, measurements are identified, including the first motor current, the second motor current, the motor voltage, and the encoder count. In block 470, it is determined whether there is a second inconsistency. If not, flow proceeds to block 475. In block 475, the system is deemed to be OK, and flow ends at block 495. If, at block 440, a first inconsistency is identified, or at block 470, a second inconsistency is identified, flow proceeds from that respective block to block 485. In block 485, a failure mode, severity, and/or corrective actions are diagnosed. In an example, the failure modes that can be detected include the motor being connected or disconnected, a cable having a short circuit to ground, a cable having a short circuit to power, encoder failures, the motor being connected incorrectly, mechatronic system failures, switch (MOSFETS) or other driving system damage, sensing system damage, encoder reader damage, and the detection of more than one failure mode. In block 490, a notification is provided, and flow ends at block 495.

[0036] Thus, examples described herein may use predictive maintenance to save time in maintenance and increase printer usage, in contrast to a drawn out and non-automated troubleshooting and diagnosis. Smart mechatronics and engine failure recognition avoids a need for lengthy maintenance time, enabling cost savings and increasing printer availability and productivity. Smart mechatronics and engine failure recognition is intelligent and does not need user intervention, while remaining consistently successful without a need to impose on operators or computer repair specialists. Circuits can measure voltage and current accurately, and improve short-circuit, open-circuit and driver fault detection. Measured data may identify one unique or more failing systems in order to reduce and simplify repair time. Uniquely and specifically identifying the cause of a problem avoids a need to unnecessarily swap out replacement parts that do not need replacing, avoiding wasted resources and time.

[0037] Examples provided herein (e.g., methods) may be implemented in hardware, software, or a combination of both. Example systems (e.g., printers) can include a controller/processor and memory resources for executing instructions stored in a tangible non-transitory medium (e.g., volatile memory, non-volatile memory, and/or computer readable media). Non-transitory computer-readable medium can be tangible and have computer-readable instructions stored thereon that are executable by a processor to implement examples according to the present disclosure.

[0038] An example system can include and/or receive a tangible non- transitory computer-readable medium storing a set of computer-readable instructions (e.g., software). As used herein, the controller/processor can include one or a plurality of processors such as in a parallel processing system. The memory can include memory addressable by the processor for execution of computer readable instructions. The computer readable medium can include volatile and/or non-volatile memory such as a random access memory ("RAM"), magnetic memory such as a hard disk, floppy disk, and/or tape memory, a solid state drive ("SSD"), flash memory, phase change memory, and so on.

Claims

WHAT IS CLAIMED IS:

1 . A device comprising:

a drive circuit to drive a motor;

a voltage circuit coupled to the drive circuit, to be coupled in parallel with the motor, to identify a motor voltage measurement;

a first current circuit coupled in series with the drive circuit to identify a first motor current measurement;

a second current circuit to be coupled in series with the motor to identify a second motor current measurement; and

a controller to identify a condition of the device based on the motor voltage measurement, the first motor current measurement, and the second motor current measurement, and provide a notification corresponding to the condition.

2. The device of claim 1 , further comprising an encoder to be mechanically coupled to the motor to identify a motor status; wherein the controller is to identify the condition of the device based on the motor status.

3. The device of claim 1 , wherein the drive circuit is an H-bridge.

4. The device of claim 1 , further comprising a memory coupled to the controller and containing stored measurements; wherein the controller is to compare the motor voltage measurement, the first motor current measurement, and the second motor current measurement to the stored measurements to identify the condition of the device.

5. The device of claim 1 , wherein the first current circuit includes a first amplifier coupled to a first analog-to-digital converter (ADC) to identify the first motor current measurement based on output from the first amplifier.

6. The device of claim 5, wherein the first current circuit includes a first low-pass filter coupled between the first amplifier and the first ADC.

7. The device of claim 1 , wherein the second current circuit includes a second amplifier coupled to a second ADC to identify the second motor current measurement based on output from the second amplifier.

8. The device of claim 7, wherein the second amplifier is an instrumentation amplifier supporting bidirectional current measurement, including a voltage reference coupled to an offset input of the instrumentation amplifier.

9. The device of claim 7, wherein the second current circuit includes a second low-pass filter coupled between the second amplifier and the second ADC.

10. The device of claim 1 , wherein the voltage circuit includes a voltage divider and a third ADC to read the motor voltage.

1 1 . A printer comprising:

a printer motor;

an H-bridge coupled to the printer motor to drive the printer motor;

a voltage circuit coupled in parallel with the printer motor to identify a motor voltage measurement;

a first current circuit coupled in series with the H-bridge to identify a first motor current measurement;

a second current circuit coupled in series with the printer motor to identify a second motor current measurement; and

a controller to identify a condition of the printer based on the motor voltage measurement, the first motor current measurement, and the second motor current measurement, and provide a notification corresponding to the condition.

12. A method, comprising:

actuating a motor in a first direction, based on a controller to control a drive circuit coupled to the motor;

identifying a motor position, based on an encoder coupled to the motor; identifying a motor voltage measurement, based on a voltage circuit coupled in parallel with the motor;

identifying a first motor current measurement, based on a first current circuit coupled in series with the drive circuit;

identifying a second motor current measurement, based on a second current circuit coupled in series with the motor;

checking for a first inconsistency in the motor position, the motor voltage, the first motor current, and the second motor current;

actuating the motor in a second direction opposite the first direction;

checking for a second inconsistency in the motor position, the motor voltage, the first motor current, and the second motor current; and

identifying a failure mode, based on the first inconsistency and the second inconsistency.

13. The method of claim 12, further comprising storing acceptable values for the motor position, the motor voltage, the first motor current, and the second motor current; and determining inconsistencies based on the stored acceptable values.

14. The method of claim 12, further comprising identifying a plurality of concurrent failure modes based on the checked parameters.

15. The method of claim 12, wherein failure modes include the motor being connected incorrectly, a failed drive circuit, a failed encoder, a failed voltage circuit, a failed first current circuit, a failed second current circuit, and a short circuit in a coupling associated with the motor.