U
Hi all 
I have the following control challenge and would be grateful for some help
Below you find the system description first followed by the challenge description below.
***** System description (chain vertical items with two side-branches):
Encoder (1)
|
EC-Motor (2)
|
Gearbox (3) - attached to the surrounding
|
Winch (to reel/unreel the rope) (4)
|
Rope (5a)
|
Rope (5b) around a 180°-Pulley (6) - Pulley attached to the Load Cell (7) - Load Cell attached to the surrounding
|
Rope (5c) (varying between 20 cm and 100 cm)
|
Rubber-ring (only a few cm) (8)
|
Hand/Arm (9a) of a Person (9b)
|
Person attached to the surrounding
The system invokes a closed-loop control (PI) of the displacement of the rope (5) measured by the encoder (1) with underlying velocity and current control loops. The key-aspect of the system is: the set-value for the displacement of the rope (5) depends on the force measured by the load cell (7) at the pulley (6)! The update rate at the top level (force, displacement) is approx. 50 per second - unfortunately hardly increasable.
Generally speaking the system simulates a spring - the larger the displacement of the rope (5) due to being pulled out by the hand (9a) of the person (9b) the stronger he/she has to pull (increasing force).
***** Challenge description:
The challenge is to find a control method which increases the dynamic of the system for fast changes of the pulling by the person (9b) but does not result in a kind of shaking in general.
At the system mentioned above I chose the control parameter so that there is only a little bit of shaking and I use a rubber-ring (8) to separate the hand/arm (9a) from the rope (5c) thus the little remaining shaking is not reaching the hand/arm (9a). However the dynamic of the system is still to low. Meaning that when the hand (9a)/person (9b) pulls fast on the rubber-ring (8) the force increases quite a lot. Due to the chosen control parameters a relative big deviation in load is needed in order to unreel the rope (5) at the winch (4) fast.
I am looking for a control solution which does not need the rubber-ring. And which results in only low deviations of the force, when the pulling is changed fast (for both pulling stronger and less strong).
Thanks a lot
Ulrich
I have the following control challenge and would be grateful for some help
Below you find the system description first followed by the challenge description below.
***** System description (chain vertical items with two side-branches):
Encoder (1)
|
EC-Motor (2)
|
Gearbox (3) - attached to the surrounding
|
Winch (to reel/unreel the rope) (4)
|
Rope (5a)
|
Rope (5b) around a 180°-Pulley (6) - Pulley attached to the Load Cell (7) - Load Cell attached to the surrounding
|
Rope (5c) (varying between 20 cm and 100 cm)
|
Rubber-ring (only a few cm) (8)
|
Hand/Arm (9a) of a Person (9b)
|
Person attached to the surrounding
The system invokes a closed-loop control (PI) of the displacement of the rope (5) measured by the encoder (1) with underlying velocity and current control loops. The key-aspect of the system is: the set-value for the displacement of the rope (5) depends on the force measured by the load cell (7) at the pulley (6)! The update rate at the top level (force, displacement) is approx. 50 per second - unfortunately hardly increasable.
Generally speaking the system simulates a spring - the larger the displacement of the rope (5) due to being pulled out by the hand (9a) of the person (9b) the stronger he/she has to pull (increasing force).
***** Challenge description:
The challenge is to find a control method which increases the dynamic of the system for fast changes of the pulling by the person (9b) but does not result in a kind of shaking in general.
At the system mentioned above I chose the control parameter so that there is only a little bit of shaking and I use a rubber-ring (8) to separate the hand/arm (9a) from the rope (5c) thus the little remaining shaking is not reaching the hand/arm (9a). However the dynamic of the system is still to low. Meaning that when the hand (9a)/person (9b) pulls fast on the rubber-ring (8) the force increases quite a lot. Due to the chosen control parameters a relative big deviation in load is needed in order to unreel the rope (5) at the winch (4) fast.
I am looking for a control solution which does not need the rubber-ring. And which results in only low deviations of the force, when the pulling is changed fast (for both pulling stronger and less strong).
Thanks a lot
Ulrich
