SPRUHJ0C April   2013  – October 2021 TMS320F28068M , TMS320F28069-Q1 , TMS320F28069M , TMS320F28069M-Q1

 

  1. 1Read This First
    1. 1.1 About This Manual
    2. 1.1 Glossary
    3. 1.1 Support Resources
    4.     Trademarks
  2. 1 F2806xM InstaSPIN-MOTION Enabled MCUs
  3. 2InstaSPIN-MOTION Key Capabilities and Benefits
    1. 2.1 Overview
    2. 2.2 FAST Unified Observer
    3. 2.3 SpinTAC Motion Control Suite
      1.      IDENTIFY
      2.      CONTROL
      3.      MOVE
      4.      PLAN
    4. 2.4 Additional InstaSPIN-MOTION Features
  4. 3InstaSPIN-MOTION Block Diagrams
    1.     Scenario 1: InstaSPIN-MOTION Speed Control with FAST Software Encoder
    2.     Scenario 2: InstaSPIN-MOTION Speed Control with a Mechanical Sensor
    3.     Scenario 3: InstaSPIN-MOTION Position Control with Mechanical Sensor and Redundant FAST Software Sensor
  5. 4Application Examples
    1. 4.1 Treadmill Conveyor: Smooth Motion Across Varying Speeds and Loads
    2. 4.2 Video Camera: Smooth Motion and Position Accuracy at Low Speeds
    3. 4.3 Washing Machine: Smooth Motion and Position Accuracy at Low Speeds
      1.      Agitation Cycle
      2.      Spin Cycles
    4. 4.4 InstaSPIN-MOTION Works Over the Entire Operating Range
  6. 5Evaluating InstaSPIN-MOTION Performance
    1. 5.1 Overview
    2. 5.2 Velocity Control Performance: SpinTAC vs PI
      1. 5.2.1 Disturbance Rejection
      2. 5.2.2 Reference Tracking
      3. 5.2.3 Step Response
    3. 5.3 Position Control Performance: SpinTAC vs PI
      1. 5.3.1 Disturbance Rejection
      2. 5.3.2 Reference Tracking
      3. 5.3.3 Step Response
      4. 5.3.4 Inertia Estimation Repeatability
  7. 6Microcontroller Resources
    1. 6.1 CPU Utilization
    2. 6.2 Memory Utilization
    3. 6.3 Pin Utilization
      1.      A Resources
        1.       B Definition of Terms and Acronyms
          1.        C Revision History

Disturbance Rejection

Disturbance rejection tests the controller's ability to compensate for external disturbances, which impact the motor speed. In the disturbance rejection test, a load torque is applied to the system, held on for a short period of time, and then removed from the system. Figure 6-3 is an example of a disturbance rejection test. The response of the controller is measured using the maximum speed error and settling time. The maximum speed error shows the deviation from the goal speed, and is an indication of how aggressively your controller is tuned. Aggressive tuning produces a low maximum error. In Figure 6-3 the PI controller presents a greater maximum speed error than the SpinTAC controller, indicating that the SpinTAC controller is more responsive in compensating for system error.

Settling time refers to the amount of time from the point when the disturbance happens until the speed returns to a fixed band around the goal speed. This is also an indication of how aggressively your control loop is tuned. If the controller is tuned too aggressively it will have a long settling time because it will oscillate around the goal speed before settling. In Figure 6-3, the PI controller has a longer setting time that the SpinTAC controller. Note that there is very little oscillation in either controller as they settle back to the goal speed.

GUID-F279EE71-7AE7-4BDC-9E8B-D44269CA9C45-low.pngFigure 5-3 Disturbance Rejection Test of Maximum Speed Error and Settling Time

 

There may be a difference in settling time when loads are applied to the system, and when loads are removed from the system. When a load is applied to a motor, the controller may reach saturation, at which point the controller's output is limited. However, when the load is removed, the motor transitions from a loaded state to zero load. The settling time and overshoot is entirely dependent upon the controller. Figure 6-4 shows an example of this case where the controller was placed into saturation.

When performing disturbance rejection testing it is important to test at multiple speed and load combinations. Speed controllers have different performance characteristics when placed into different situations. In order to properly evaluate the effectiveness of your speed controller, tests should be performed across the entire application operating range. The test results will indicate whether the controller will meet the application specifications, or whether the controller needs to be tuned multiple times for different operating points (gain scheduling). The following test results were obtained for nine different speed and load combinations in order to test a wide range of operation.

It is also important to be able to create repeatable disturbances. This can be accomplished using a dynamometer or a disturbance motor. Creating repeatable disturbance is an important factor when evaluating multiple controllers. If test conditions cannot be replicated, it is difficult to adequately compare the responses of multiple controllers.

GUID-6BA0A4EA-597C-49F2-B7D4-82D4593F1C1F-low.pngFigure 5-4 Disturbance Rejection Test with Controller Saturation

 

For the test results shown in Table 6-2 and Table 6-3, a disturbance load profile was created that applied 25%, 50%, and 100% of rated torque to the motor. The test compared the performance of the SpinTAC speed controller to a standard PI controller, and the following parameters were measured for each:

  • Average Recovery Time (from the point of disturbance until within 2% of the target speed): The average recovery time was measured when the load was applied and when the load was removed from the system.
  • Absolute Average Speed Error: The positive or negative deviation from the goal speed when a system disturbance is introduced.
  • Maximum Speed Error: The maximum deviation from goal speed when a disturbance is introduced.

Table 5-2 SpinTAC vs PI Disturbance Rejection Test Results (Teknic Motor)
1000 rpm 2000 rpm 4000 rpm
SpinTAC PI SpinTAC Advantage (percentage improvement over PI) SpinTAC PI SpinTAC Advantage (percentage improvement over PI) SpinTAC PI SpinTAC Advantage (percentage improvement over PI)
25% rated torque
Avg Recovery Time(s) - load applied 1.34 1.84 27.34 1.20 1.67 28.27 0.85 1.79 52.46
Avg Recovery Time(s) - load removed 0.43 0.93 53.29 0.41 0.89 53.55 0.54 1.02 46.82
Abs Avg Error (rpm) 3.06 4.16 26.44 5.98 6.63 9.74 12.23 12.42 1.53
Avg Max Error (rpm) 17 29 41.38 16 27 40.74 18 26 30.77
50% rated torque
Avg Recovery Time(s) - load applied 1.01 1.33 23.81 1.01 1.45 30.34 4.98 5.04 1.19
Avg Recovery Time(s) - load removed 0.51 1.04 51.30 0.56 1.06 46.52 1.33 2.54 47.20
Abs Avg Error (rpm) 3.7 7.9 53.16 6.21 10.2 39.12 81.92 87.66 6.55
Avg Max Error (rpm) 36 71 49.30 35 69 49.28 197 185 -6.49
100% rated torque
Avg Recovery Time(s) - load applied 0.76 1.20 36.67 0.78 1.16 32.73 4.98 5.08 1.95
Avg Recovery Time(s) - load removed 0.40 1.00 59.84 0.52 1.02 48.89 1.90 3.12 39.09
Abs Avg Error (rpm) 5.4 15.39 64.91 7.99 17.54 54.45 345.42 360.74 4.25
Avg Max Error (rpm) 87 158 44.94 80 151 47.02 829 837 0.96
Table 5-3 SpinTAC vs PI Disturbance Rejection Test Results (Estun Motor)
750 rpm1500 rpm3000 rpm
SpinTACPISpinTAC Advantage (percentage improvement over PI)SpinTACPISpinTAC Advantage (percentage improvement over PI)SpinTACPISpinTAC Advantage (percentage improvement over PI)
25% rated torque
Avg Recovery Time(s) - load applied0.691.5254.340.601.3657.960.601.3552.87
Avg Recovery Time(s) - load removed0.421.1261.750.401.0361.580.411.0159.01
Abs Avg Error (rpm)1.973.8148.133.055.2541.906.169.0832.12
Avg Max Error (rpm)374721.28364723.40384922.45
50% rated torque
Avg Recovery Time(s) - load applied0.351.3172.970.331.3376.230.361.1367.07
Avg Recovery Time(s) - load removed0.441.3667.320.401.2568.020.3641.1467.33
Abs Avg Error (rpm)2.675.9154.873.867.1345.896.8911.1438.19
Avg Max Error (rpm)769620.83749522.11769721.65
100% rated torque
Avg Recovery Time(s) - load applied0.562.2675.090.52.1476.684.985.061.58
Avg Recovery Time(s) - load removed0.381.1666.780.40.9255.930.440.7440.60
Abs Avg Error (rpm)8.6457.9885.099.5459.9584.0994.25103.749.15
Avg Max Error (rpm)44069736.8744066533.835856469.44