Editing Signal path of motor drive
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*Input multiplier. Purpose of this is to increase resolution of input setpoint to allow more fine grained velocity & acceleration control in trajectory planner. By default {{param|MUL}} value is 50. | *Input multiplier. Purpose of this is to increase resolution of input setpoint to allow more fine grained velocity & acceleration control in trajectory planner. By default {{param|MUL}} value is 50. | ||
*Setpoint smoothing filter. If enabled, applies low pass filter to signal reducing jitter and roughness of signal but also introduces about some delay. By default the filter has 100% attenuation at 250Hz. | *Setpoint smoothing filter. If enabled, applies low pass filter to signal reducing jitter and roughness of signal but also introduces about some delay. By default the filter has 100% attenuation at 250Hz. | ||
− | * | + | *Trajectory planner. This limits rate of change of setpoint signal based on {{param|CVL}} and {{param|CAL}} parameters. Output rate maximum rate of change: |
**Velocity changes max {{param|CAL}} nubmer of units per [[control cycle]] (control cycle is 400µs in most GD drives) | **Velocity changes max {{param|CAL}} nubmer of units per [[control cycle]] (control cycle is 400µs in most GD drives) | ||
**Velocity maximum value is limited to {{param|CVL}} | **Velocity maximum value is limited to {{param|CVL}} | ||
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* Velocity mode: frequency input, setpoint = number of edges of either channel per [[control cycle]] | * Velocity mode: frequency input, setpoint = number of edges of either channel per [[control cycle]] | ||
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− | | PWM || rowspan= | + | | PWM || rowspan=2 |Absolute || Full input scale equals setpoint range of +/-16384. In loss of PWM signal, setpoint is 0. || rowspan=3 | |
*Direct 1:1 absolute value in position mode | *Direct 1:1 absolute value in position mode | ||
− | *Velocity & torque mode: +/- | + | *Velocity & torque mode: +/-16834 represents full torque or speed scale |
|- | |- | ||
| Analog || Full input scale equals setpoint range of +/-16384 | | Analog || Full input scale equals setpoint range of +/-16384 | ||
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− | [[File:Driveblockdiagram controller.png| | + | [[File:Driveblockdiagram controller.png|800px]] |
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− | + | ==Setpoint scale examples== | |
+ | Assuming control cycle to be 400µs / 2500 Hz (default in GD drives). | ||
− | + | ===Example 1=== | |
+ | ;Calculating setpoint | ||
+ | *Motor has 2500 P/R encoder (10000 CPR) and user wants to rotate it at 1000 rpm in velocity mode. Scaling is set to 1:1 (MUL/DIV ratio is 1) | ||
+ | *Rotation speed is 1000/60 = 16.667 revs/s (RPS) Needed encoder count frequency is 16.667*10000 = 16667 counts/s. | ||
+ | *Internal setpoint is the amount of counts per control cycle so in this case it's 16667/2500 = 66.667 | ||
− | + | Because set point is integer value user must round setpoint to 66 or 67. To achieve exact speed, he could change input scaling (MUL/DIV) to allow unrounded value here. | |
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− | + | ;Calculating acceleration and velocity limits | |
− | + | If DIV is 50, then user must have {{param|CVL}} value at least 3333 (66.6667*50). | |
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+ | If user wants motor to accelerate to 1000 rpm in 0.1 seconds, then {{param|CAL}} is value should be 3333/2500/0.1 = 13.33. Value must be again rounded to integer and rounding error could be reduced by adjusting scaling (adjust DIV). | ||
{{tip|Granity calculates real world units thus it can be used to calculate and experiment with the scales. As scales are linear, interpolation of values is viable choice.}} | {{tip|Granity calculates real world units thus it can be used to calculate and experiment with the scales. As scales are linear, interpolation of values is viable choice.}} | ||
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