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

Reference Tracking

Reference tracking tests how well the controller follows a changing position target. The two metrics to evaluate in these tests are the maximum error and the absolute average error. The maximum position error shows how much the controller overshoots while changing speeds. This is an indication of how aggressively your controller is tuned. If you controller is not tuned aggressively enough, the speed will overshoot the target, and will take a long time to recover. If the controller is tuned too aggressively it will overshoot, and then oscillate as it settles on the position target. If the controller is correctly tuned, it will minimally overshoot and then smoothly return to the position target.

Absolute average error is an average of the absolute value of the instantaneous position error over the entire profile. This measure shows the amount of deviation throughout the entire profile. It takes into account all of the little errors as the motor is running. If the controller is tuned too aggressively it will result in larger absolute average error because the controller will be oscillating throughout the profile. If the controller is not tuned aggressively enough, it will result in a larger absolute average error because it is continuously falling behind the commanded profile.

A position tracking profile was created to exercise the motor in a repeatable a pattern. The profile was used to compare the performance of SpinTAC Position Control and the PI control system. The profile included quick transitions as well as gentle sweeping transitions. Figure 6-11 is a plot of the reference profile that was used in the tests.

GUID-C4E01848-B29E-4C1F-9C93-B4139611D1BB-low.png Figure 5-11 Position Profile Used During Reference Tracking Test


The blocked off area has an additional plot that will highlight the differences between SpinTAC and PI controllers.

Figure 6-12 is the first part of the position reference tracking test. The red line at the bottom of the chart is the PI position error. The green line is the SpinTAC position error. Notice that the PI position error is much larger when making transitions and it also has an offset when in the constant velocity section of the profile. While SpinTAC has no issues with tracking the profile and has much less error than the PI controller.

GUID-581647DE-333E-4DCA-B984-7688CBD45F90-low.png Figure 5-12 PI Error During Position Tracking


It is important to test multiple speeds and accelerations in your position profile as well as multiple different loads. Position controllers have different performance characteristics when placed into different situations. In order to properly evaluate the effectiveness of your controller, tests should be conducted across the entire application range. This includes when you design the profile for testing. Care needs to be taken to ensure that the application speeds and accelerations are built into the position profile. The results of these tests will indicate whether the controller will meet the application specifications, or if the controller needs to be tuned multiple times for different operating points. You should notice in Figure 6-11 that there is a wide range of speeds and accelerations that are tested.

It is also important to be able to create repeatable profiles. Creating a repeatable profile can be done using SpinTAC Move and SpinTAC Plan (the InstaSPIN-FOC and InstaSPIN-MOTION User's Guide provides detailed information on SpinTAC Move and SpinTAC Plan, and lab projects are available in the MotorWare repository). Repeatable profiles are required if position controllers are being compared. A repeatable profile ensures that the controllers will be tested using the same reference in the same order and for the same length of time, and that test conditions are as identical as possible. The profile for this test was made using SpinTAC Move and SpinTAC Plan.

The following parameters were measured:

  • Absolute Average Position Error - deviation (in mechanical degrees) from the target over the entire position profile.
  • Maximum Position Error - maximum deviation (in mechanical degrees) from the goal position during the position profile.
Table 5-9 SpinTAC vs PI Position Profile Tracking Test Results
Trapezoidal Curve st-Curve
SpinTAC PI SpinTAC Advantage (percentage improvement over PI) SpinTAC PI SpinTAC Advantage (percentage improvement over PI)
Teknic Motor
Abs Avg Error (mechanical degrees) 3.6e-1 5.98 94.0 3.95e-1 4.54 91.5
Max Error (mechanical degrees) 3.85 95.8 96.0 4.03 53089 92.5
Estun Motor
Abs Avg Error (mechanical degrees) 3.32e-1 10.19 96.7 3.48e-1 51.05 99.3
Max Error (mechanical degrees) 2.12 126.75 98.3 1.76 113.55 98.4