.

Shape Pattern of Kaff

The plots below show the linear relationship between Kaff and the Position Error of a commanded move.

NOTE: All peak error measurements were made during the first half of the move for comparison purposes.

  10,000 count move
Trapezoidal move:
      5e5 accel, decel, vel
Green - Commanded Velocity             
Yellow - Commanded Acceleration                   
White - Position Error
 

Kaff = 0
Kp = 100
Ki = 0
Kd = 2,000
Peak Position Error = 188 counts 

 

  10,000 count move
Trapezoidal move:
      5e5 accel, decel, vel
Green - Commanded Velocity             
Yellow - Commanded Acceleration                   
White - Position Error
 

Kaff = 20,000
Kp = 100
Ki = 0
Kd = 2,000
Peak Position Error = 154 counts 

 

  10,000 count move
Trapezoidal move:
      5e5 accel, decel, vel
Green - Commanded Velocity             
Yellow - Commanded Acceleration                   
White - Position Error
 

Kaff = 70,000
Kp = 100
Ki = 0
Kd = 2,000
Peak Position Error = 72 counts 

 

  10,000 count move
Trapezoidal move:
      5e5 accel, decel, vel
Green - Commanded Velocity             
Yellow - Commanded Acceleration                   
White - Position Error
 

Kaff = 100,000
Kp = 100
Ki = 0
Kd = 2,000
Peak Position Error = 28 counts 

 

  10,000 count move
Trapezoidal move:
      5e5 accel, decel, vel
Green - Commanded Velocity             
Yellow - Commanded Acceleration                   
White - Position Error
 

Kaff = 120,000
Kp = 100
Ki = 0
Kd = 2,000
Peak Position Error = –16 counts 

 

  10,000 count move
Trapezoidal move:
      5e5 accel, decel, vel
Green - Commanded Velocity             
Yellow - Commanded Acceleration                   
White - Position Error
 

Kaff = 170,000
Kp = 100
Ki = 0
Kd = 2,000
Peak Position Error = –98 counts 

 

  10,000 count move
Trapezoidal move:
      5e5 accel, decel, vel
Green - Commanded Velocity             
Yellow - Commanded Acceleration                   
White - Position Error
 

Kaff = 200,000
Kp = 100
Ki = 0
Kd = 2,000
Peak Position Error = –150 counts 

To emphasize the linear relationship between Kaff and Position Error, the grpah below summarizes the data from the above plots. There is some non-linearity near the zero position error because of the unsophisticated manner in which position error is determined.

 

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