# Menu 39 − AMC Position Control Loop

Mode: RFC‑S

Position control loop

Parameter | 39.001 AMC External Position Reference Select
--- | ---
Short description |
Mode | RFC‑S
Minimum | 0 | Maximum | 1
Default | 0 | Units |
Type | 1 Bit User Save | Update Rate | Background read
Display Format | Standard | Decimal Places | 0
Coding | RW

If AMC External Position Reference Select (39.001) = 0 the position, speed and acceleration reference for the position control loop is taken from the output of the profile generator. However, it is possible to provide these references from an external application (i.e. an applications category module program). If AMC External Position Reference Select (39.001) = 1 the position reference is taken from AMC External Position Reference (39.002) the speed reference is taken from AMC External Speed Reference (39.004) and the acceleration reference is taken from AMC External Acceleration Reference (39.014).

Parameter | 39.002 AMC External Position Reference
--- | ---
Short description |
Mode | RFC‑S
Minimum | −VM_AMC_SPEED | Maximum | VM_AMC_SPEED
Default | 0 | Units | UU
Type | 32 Bit Volatile | Update Rate | AMC sample rate read
Display Format | Standard | Decimal Places | 0
Coding | RW, VM

See AMC External Position Reference Select (39.001).

Parameter | 39.004 AMC External Speed Reference
--- | ---
Short description |
Mode | RFC‑S
Minimum | −VM_AMC_POSITION | Maximum | VM_AMC_POSITION
Default | 0.00 | Units | UU/ms
Type | 32 Bit Volatile | Update Rate | AMC sample rate read
Display Format | Standard | Decimal Places | 2
Coding | RW, VM

See AMC External Position Reference Select (39.001).

Parameter | 39.005 AMC Inertia Compensation Mode
--- | ---
Short description |
Mode | RFC‑S
Minimum | 0 | Maximum | 2
Default | 0 | Units |
Type | 8 Bit User Save | Update Rate | Background read
Display Format | Standard | Decimal Places | 0
Coding | RW, TE

Value | Text
0 | None
1 | Acceleration
2 | Torque

AMC Inertia Compensation Mode (39.005) selects the inertia compensation mode as shown below.

0 (None)

No inertia compensation.

1 (Acceleration feed-forwards)

When acceleration feed-forwards is selected a gain term is automatically calculated based on the currently active drive speed controller gains, Motor And Load Inertia (03.018) and Torque Per Amp (05.032). The acceleration feed-forwards term is intended to cancel the effect of the speed controller time constant and give a faster position control loop response and should only be used with a first order speed controller, i.e. Speed Controller Set-up Method (03.017) = 7.

2 (Torque feed-forwards)

When torque feed-forwards is selected the acceleration from the profile generator is used to define the torque feed-forwards. The Motor And Load Inertia (03.018), Torque Per Amp (05.032) and the output user units ratio are used to convert from acceleration to torque. It should be noted that the Inertia Compensation Torque (02.038) is added to the output of the speed controller when Inertia Compensation Enable (04.022) = 1.

Note that inertia compensation is disabled when AMC External Position Reference Select (39.001) = 1.

Parameter | 39.007 AMC Position Control Loop Kp Gain
--- | ---
Short description |
Mode | RFC‑S
Minimum | 0.000 | Maximum | 500.000
Default | 25.000 | Units |
Type | 32 Bit User Save | Update Rate | Background read
Display Format | Standard | Decimal Places | 3
Coding | RW

AMC Position Control Loop Kp Gain (39.007) is the proportional gain with units of (User units/s) / User units. A AMC Position Control Loop Kp Gain (39.007) of unity and a AMC Position Error (39.008) of one User unit will give a position control loop speed of 1 User unit/s.

Parameter | 39.008 AMC Position Error
--- | ---
Short description |
Mode | RFC‑S
Minimum | −VM_AMC_POSITION | Maximum | VM_AMC_POSITION
Default |  | Units | UU
Type | 32 Bit Volatile | Update Rate | 4ms write
Display Format | Standard | Decimal Places | 0
Coding | RO, FI, VM, ND, NC, PT

AMC Position Error (39.008) gives the difference between the final position reference and the AMC Slave Position (33.004) in User units.

Parameter | 39.009 AMC Position Control Loop Speed Clamp
--- | ---
Short description |
Mode | RFC‑S
Minimum | −VM_AMC_SPEED_UNIPOLAR | Maximum | VM_AMC_SPEED_UNIPOLAR
Default | 109.20 | Units | UU/ms
Type | 32 Bit User Save | Update Rate | Background read
Display Format | Standard | Decimal Places | 2
Coding | RW, VM

The default value of 109.2 UU/ms is the equivalent of 100rpm for a 16 bits per revolution feedback device with a user units ratio = 1.

The AMC Position Control Loop Speed Clamp (39.009) defines the maximum positive or negative speed output from the position control loop in User units/ms.

Parameter | 39.010 AMC Speed Feed-forwards Gain
--- | ---
Short description |
Mode | RFC‑S
Minimum | 0.000 | Maximum | 2.000
Default | 1.000 | Units |
Type | 16 Bit User Save | Update Rate | Background read
Display Format | Standard | Decimal Places | 3
Coding | RW

Normally the speed feed-forwards is used directly to provide the speed reference for the drive, with the position controller to trim this to give the correct position. In some applications it is necessary to reduce the speed feed-forwards component to reduce overshoot. The default value of AMC Speed Feed-forwards Gain (39.010) is unity, but this can be reduced to reduce the speed feed-forwards component.

Parameter | 39.011 AMC Output Speed Clamp
--- | ---
Short description |
Mode | RFC‑S
Minimum | −VM_SPEED_FREQ_REF | Maximum | VM_SPEED_FREQ_REF
Default | 1000.0 | Units |
Type | 32 Bit User Save | Update Rate | Background read
Display Format | Standard | Decimal Places | 1
Coding | RW, VM

AMC Output Speed Clamp (39.011) provides a final clamp on the output speed in drive speed parameter units (i.e. rpm or mm/s).

Parameter | 39.012 AMC Output Speed
--- | ---
Short description |
Mode | RFC‑S
Minimum | −VM_SPEED_FREQ_REF | Maximum | VM_SPEED_FREQ_REF
Default |  | Units |
Type | 32 Bit Volatile | Update Rate | 4ms write
Display Format | Standard | Decimal Places | 1
Coding | RO, FI, VM, ND, NC, PT

AMC Output Speed (39.012) is the final output from the Advanced Motion Controller in 0.1rpm or 0.1mm/s. Although the update rate for this parameter is 4ms the output speed is written to the Hard Speed Reference (03.022) at the sample rate selected in AMC Rate Select (31.012). The output speed is written in internal units (232cpr/250μs) to increase the maximum speed resolution to 5.59e-5rpm or Pole Pitch x 9.31e-7mm/s.

Parameter | 39.013 AMC Output Invert
--- | ---
Short description | Set to 1 to invert the AMC output speed
Mode | RFC‑S
Minimum | 0 | Maximum | 1
Default | 0 | Units |
Type | 1 Bit User Save | Update Rate | Background read
Display Format | Standard | Decimal Places | 0
Coding | RW

If AMC Output Invert (39.013) = 1 then AMC Output Speed (39.012) and the output torque (AMC Inertia Compensation Mode (39.005) = 2) is inverted.

Parameter | 39.014 AMC External Acceleration Reference
--- | ---
Short description |
Mode | RFC‑S
Minimum | −VM_AMC_RATE | Maximum | VM_AMC_RATE
Default | 0.000 | Units | UU/ms²
Type | 32 Bit Volatile | Update Rate | AMC sample rate read
Display Format | Standard | Decimal Places | 3
Coding | RW, VM

See AMC External Position Reference Select (39.001).