Hoist cable tension control via ACOPOS drive

Ask Questions Mechatronics & Motion
1

Hello,
I am coming back to you with a structured customer request regarding hoist/winch cable tension control, based on concrete field feedback.
Current situation
The customer is already estimating the load via the drive sing the following principles:

Reading of magnetizing current / effective motor current
Motor torque calculation
Indirect estimation of cable tension

The theoretical fundamentals are therefore well understood by the customer.
However, they are facing significant limitations in terms of accuracy and repeatability, mainly due to:
Strong variations of mechanical efficiency over time, major influence of the number of cable layers on the drum** (hoisting vs lowering completely changes the real load), temperature effects, overall, mechanical losses (gearbox, drum, cable guidance).

:right_arrow: As a result, the torque-based estimation at motor level is often **far from the real cable tension.

In parallel, the customer does have **advanced solutions with dedicated load sensors, but these are considered:
costly,
complex to integrate,
poorly suited for certain **special-purpose machines (perceived as “overengineered” solutions).
Questions to B&R
In this context, could you please clarify:

  1. Does B&R offer a tension control or regulation function integrated in the ACOPOS drive, beyond a simple motor torque estimation?
  2. If yes:
    on which physical and algorithmic principles is it based ?
    what are the known limitations with respect to the phenomena mentioned above (cable layers, mechanical losses, temperature, varying efficiency) ?

Thank you for your feedback

2

While I can’t confidently say that B&R has an immediate solution for this case scenario, I think a look at “mapp Web” or the “Winder Closed-loop tension control” example might be something check out. Maybe someone might be able to dive deeper into the “nitty gritty” of things.

mappWebb: Winder Closed-Loop Tension Control
Winder closed loop Tension control: Winder Closed-Loop Tension Control

3

Hello,

i am not an expert for hoisting or winding and the issues you descripe that the motor does not see the direct load due to mechanics is often an issue you can only solve with a sensor.

But for your question about how the Torque is calculated i think this article in the Automation Studio can bring you a bit forward. There are different possible modes descriped. Mainly a Default-Mode and a Advance-Observer Mode.

Torque Calculation

I would also at least check if changing the cycle Time of the ACOPOS will improve behaviour
Controller Cascade Cycle Time

Current Controller Control Mode

Switching Frequency

Are they currently working with Position-Control or did they disabled the Position-Control and only work with Velocity/Current-Control.

I am also interessted what other experts can contribute as i rarely had contact with hoisting.

Greetings
Michael

4

Hello Noah,

Thank you for the initial feedback.

5

Hello Michael,

Thank you for your feedback. I would also be interested to hear feedback from other experts.

6

HI @Sekhou_Savane , what is the status of your issue, any progress? can you update us?

7

Hi @kovarj At this stage, I haven’t received any concrete progress. Apart from the two feedback points mentioned earlier, there has been no additional response.

I shared this feedback with the customer, but so far it hasn’t led to further advancement on the topic. I will keep you informed as soon as I receive any new updates.

8

Clear. Feel free to trigger discussion by sharing new findings, thoughts, or questions.