Cogging Torque · Torque Ripple · Angle Analysis · FFT
Measure cogging torque and torque ripple with Sugawara Laboratories ATM-100 / ATV-100 systems for DC motors, BLDC motors, AC servo motors, stepping motors, and other precision motor applications.
The platform combines interchangeable torque sensors, 0.01° angle resolution, up to 36,000 data points per revolution, FFT and polar analysis, and optional external-signal acquisition for motor-development and quality-management workflows.
FIND YOUR TEST APPROACH
Choose cogging torque for non-energized magnetic torque variation, torque ripple for energized operation, or development and quality analysis when FFT and external-signal correlation are important.
Permanent-magnet motor evaluation
Measure periodic torque variation while the motor is rotated in a non-energized state. The ATM-100 / ATV-100 architecture uses vertically arranged torque sensors without axle bearings, helping avoid torque-sensor mechanical loss while capturing torque against angular position.
Recommended Sugawara test system
Angle-based motor torque test systems for cogging torque and torque-ripple evaluation. ATM-100 supports low-torque sensor ranges from 1 mN·m to 100 mN·m, while ATV-100 supports 1 N·m and 10 N·m sensor ranges.
View ATM-100 / ATV-100Motor drive and control evaluation
Evaluate cyclic torque variation while the motor is energized and driven. The same ATM-100 / ATV-100 platform can be used for torque-ripple testing, allowing engineers to compare torque behavior with angular position and, when configured with optional I/O, correlate the torque waveform with external electrical or position signals.
Recommended Sugawara test system
Angle-based motor torque test systems for cogging torque and torque-ripple evaluation. ATM-100 supports low-torque sensor ranges from 1 mN·m to 100 mN·m, while ATV-100 supports 1 N·m and 10 N·m sensor ranges.
View ATM-100 / ATV-100Analysis and engineering correlation
Use TORQuick CT to display torque data in XY, polar-coordinate, and FFT views. Optional I/O can add external voltage, current, temperature, or motor-position signals so torque characteristics can be evaluated together with control and operating data.
Recommended Sugawara test system
Angle-based motor torque test systems for cogging torque and torque-ripple evaluation. ATM-100 supports low-torque sensor ranges from 1 mN·m to 100 mN·m, while ATV-100 supports 1 N·m and 10 N·m sensor ranges.
View ATM-100 / ATV-100Cogging Torque Test Selection
Start with the expected torque magnitude and physical motor configuration. Then confirm whether the test is for non-energized cogging torque, energized torque ripple, external-signal correlation, or production-oriented comparison. ATM-100 covers lower torque ranges; ATV-100 extends the system into N·m-level measurement.
Motor torque fundamentals
Cogging torque is the periodic torque variation produced by magnetic attraction between the rotor magnets and stator teeth in a permanent-magnet motor when the motor is not energized. It can contribute to uneven rotation, noise, vibration, and disturbances that become important in precision motion and high-efficiency motor design.
Measured with the motor non-energized while the shaft is rotated through angular position. The goal is to characterize magnetic torque variation independently from drive-current effects.
Measured while the motor is energized and driven. Torque ripple reflects periodic output-torque variation created by the combined motor electromagnetic design and control behavior.
Periodic torque variation can excite mechanical structures and contribute to audible noise or vibration. Measuring the angular waveform helps engineers identify where the variation occurs.
When torque data is correlated with electrical or position signals, engineers can compare commutation, control settings, rotor position, and other factors against the measured torque waveform.
ATM-100 / ATV-100 proof points
Sugawara's ATM-100 and ATV-100 systems are designed specifically for cogging-torque and torque-ripple evaluation. Their vertically arranged torque-sensor configuration simplifies shaft alignment and avoids axle-bearing loss inside the torque sensor.
Measurement method
The ATM-100 / ATV-100 rotates the motor through a controlled angular position while a selected torque sensor captures the torque waveform. The test speed can be set from 0.1 to 20 r/min. Lower rotational speeds provide denser angular sampling, reaching 36,000 points per revolution at 0.01° intervals.
The vertical sensor arrangement uses no axle bearings in the torque sensor, reducing a potential source of mechanical-loss error and simplifying alignment of the motor shaft with the sensor shaft.
Five sensor ranges are available across the ATM-100 / ATV-100 platform: 1 mN·m, 10 mN·m, 100 mN·m, 1 N·m, and 10 N·m.
Torque is evaluated against angular position so periodic behavior can be inspected directly rather than reduced to only a single average or peak number.
ATM-100 includes an XYZ stage, while ATV-100 uses a larger standard motor fixture. Custom jigs and couplings can be considered according to motor geometry and torque characteristics.
System selection
The two testers share the same basic measurement concept but cover different torque ranges and fixture sizes. Use the expected torque level and motor geometry as the first selection criteria.
| Selection item | ATM-100 | ATV-100 |
|---|---|---|
| Torque sensor ranges | 1 mN·m / 10 mN·m / 100 mN·m | 1 N·m / 10 N·m |
| Sensor shaft diameter | φ3 mm | φ10 mm |
| Torque accuracy | ±0.5% of rated torque after calibration with ATM-100 / ATV-100 | |
| Rotation speed | 0.1–20 r/min, adjustable in 0.1 r/min increments | |
| Angle resolution | 0.01° maximum resolution | |
| Typical fixture approach | XYZ stage for smaller / lower-torque motor alignment | Larger standard motor fixture for N·m-level applications |
TORQuick CT analysis
TORQuick CT is Sugawara's motor-evaluation software for ATM-100 and ATV-100. It provides multiple views of the measured torque waveform so engineers can inspect periodic behavior and analyze frequency components rather than relying only on one numeric torque value.
Review torque versus angular position to locate peaks, valleys, and repeating torque patterns over the motor revolution.
Visualize torque behavior around the motor's rotational cycle, which can make repeating angular patterns easier to interpret.
Use frequency analysis to identify dominant periodic components and compare changes between motor designs, assembly conditions, or control settings.
With the optional I/O module, up to eight external channels can be displayed with angle-torque characteristics. Signals may include voltage, current, temperature, or motor-position data.
How to specify the test
Accurate cogging-torque testing depends on more than the torque range. Motor shaft geometry, fixture rigidity, alignment, energized or non-energized operating state, angular sampling, and any electrical or position signals required for correlation should all be defined before the test system is specified.
| Selection factor | What to confirm | Why it matters |
|---|---|---|
| Torque magnitude | Expected peak and typical cogging / ripple torque | Determines the appropriate TSA sensor range and whether ATM-100 or ATV-100 is suitable. |
| Motor geometry | Shaft diameter, protruding shaft length, mounting points, overall size | Defines fixture, coupling, and alignment requirements. |
| Measurement state | Non-energized cogging torque or energized torque ripple | Determines the test setup and whether synchronized motor power control is required. |
| Angular detail | Required angular resolution and data density | Lower rotation speed provides denser sampling, up to 36,000 points per revolution. |
| Analysis requirement | Waveform comparison, polar plot, FFT, peak-count analysis | Defines how the torque waveform will be interpreted during design or quality evaluation. |
| External signals | Voltage, current, temperature, resolver / Hall / position data | Optional I/O enables correlation of torque behavior with motor-control and operating signals. |
Related motor testing solutions
Cogging torque and torque ripple answer a specific angular-torque question. Use the related Solution pages when the engineering requirement shifts to loaded torque-speed performance, ultra-high-speed operation, stepper-motor pull-in / pull-out behavior, or environmental testing.
Frequently asked questions
Cogging torque is periodic torque variation caused mainly by magnetic interaction between rotor magnets and stator teeth and is measured with the motor non-energized. Torque ripple is periodic output-torque variation while the motor is energized and operating, so drive and control behavior can also affect the result.
Sugawara describes the systems for DC motors, BLDC motors, AC servo motors, stepping motors, and other applications that fit the available torque-sensor and fixture ranges.
ATM-100 supports 1 mN·m, 10 mN·m, and 100 mN·m sensors. ATV-100 supports 1 N·m and 10 N·m sensors.
The maximum angular resolution is 0.01°. At 0.1 to 1.5 r/min, the system can collect up to 36,000 data points per revolution at 0.01° intervals.
Sugawara states that a measurement can be completed in as little as approximately 3 seconds when the tester is operated at 20 r/min. Actual test time depends on the selected measurement conditions and workflow.
Yes. With the optional I/O module, external channels can be displayed with angle-torque characteristics. Examples include voltage, current, temperature, resolver, Hall-sensor, or motor-position signals.
Provide the motor type, expected torque range, shaft and mounting dimensions, energized or non-energized test objective, required angular resolution, target analysis method, external signals to be recorded, and whether custom fixtures or couplings are needed.
U.S. application support
Share the motor type, expected torque range, shaft dimensions, measurement objective, angular-analysis requirement, and any external signals that need to be correlated. Denkei Corporation Americas can help identify a suitable Sugawara ATM-100 / ATV-100 configuration.
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