Motor Control in Conveyor/Sortation Systems

[IdealDan]

Hi Guys!

Please, I'd like to know how Motor speed Control in Conveyor/Sortation Systems are Programmed/achieved for Factory and Warehouse operations (I'm from Process Industry background).

1. Is it via VFDs OR do they run at constant speed?

2. What are the likely/obvious day-to-day regular faults/Troubleshooting activities in conveyor/sortation systems aside Power issues, sensor failures and motor failures?

Your inputs will be highly appreciated!

 

[parky]

In sortation systems most are direct on-line motors it is rare to alter the speed I have done many warehouse systems & like I said, nearly all are direct on-line with gearboxes that are selected for the speed. however, there is a trend in some areas for speed control & invariably done by inverters (VFD), some still use a manually adjusted speed control with variable gearboxes, faults apart from what you have already posted, the other faults are generally mechanical, many conveyors are roller type using belts twisted to a central 90 Degree shaft, or possibly powered rollers where the roller itself is powered but these often use belts, so main problems snapped drive belts, bearings or rubbish build up on the rollers. pretty simple stuff really.

 

[IdealDan]

In sortation systems most are direct on-line motors it is rare to alter the speed I have done many warehouse systems & like I said, nearly all are direct on-line with gearboxes that are selected for the speed. however, there is a trend in some areas for speed control & invariably done by inverters (VFD), some still use a manually adjusted speed control with variable gearboxes, faults apart from what you have already posted, the other faults are generally mechanical, many conveyors are roller type using belts twisted to a central 90 Degree shaft, or possibly powered rollers where the roller itself is powered but these often use belts, so main problems snapped drive belts, bearings or rubbish build up on the rollers. pretty simple stuff really.

Thanks for the insight, I pretty much appreciate it.
For the Trend regarding VFDs usage, Are they using feedback loop (PID) to Control the VFD?

I will also appreciate if anyone could please share a SCADA Screen sample of a Conveyor/sortation system, how it looks like.

 

[goghie]

My experience with conveyor systems with sorting capabilities is that possibility to have control over exact speed and position of conveyed goods is big benefit. If you want sorting you need tracking usually. In order to achieve it, encoders and vector VFDs with good S-curve algorithms really help.

 

[IdealDan]

My experience with conveyor systems with sorting capabilities is that possibility to have control over exact speed and position of conveyed goods is big benefit. If you want sorting you need tracking usually. In order to achieve it, encoders and vector VFDs with good S-curve algorithms really help.

Thanks for your input Bro.
Please, could you through more on what you mean by S-curve algorithms?

 

[mylespetro]

Thanks for your input Bro.
Please, could you through more on what you mean by S-curve algorithms?

S-curves are referring to the acceleration on startup and deceleration on stopping. Instead of just a straight line, there are curves in the speed, slowly ramping up to linear and then tapering off as it reaches the target speed. This makes for gentler starts and stops, and in a conveyor application, would lessen product slipping on the belts.

Here's a decent picture of what an S-curve is.

 

[IdealDan]

S-curves are referring to the acceleration on startup and deceleration on stopping. Instead of just a straight line, there are curves in the speed, slowly ramping up to linear and then tapering off as it reaches the target speed. This makes for gentler starts and stops, and in a conveyor application, would lessen product slipping on the belts.

Here's a decent picture of what an S-curve is.

Thanks for that input.
I appreciate it Bro!

 

[Jim3846]

VFD with ethernet for both speed and control, mainly what greenfield sites use.
decel not used in some instances but use coast to stop and accel for sorter. rest of conveyor match the sorter decel.

High speed sortation its necessary to have a servo controlled gapping before sorter but have seen some use VFDs with encoders and achieve the same gapping requirements.

rest of the stuff in warehouse is basic motor control over and over x500.

 

[IdealDan]

VFD with ethernet for both speed and control, mainly what greenfield sites use.
decel not used in some instances but use coast to stop and accel for sorter. rest of conveyor match the sorter decel.

High speed sortation its necessary to have a servo controlled gapping before sorter but have seen some use VFDs with encoders and achieve the same gapping requirements.

rest of the stuff in warehouse is basic motor control over and over x500.

Thanks for the input Bro;
VFD control with Encoder is via PID control right?

 

[parky]

I agree with "JIM", I suppose the trend nowadays is to use servo or VFD's in places like gapping rather than say a solenoid operated stop for gapping.

 

[Jim3846]

Thanks for the input Bro;
VFD control with Encoder is via PID control right?

No the encoder is on the belt. Usually there is an algorithm that gives the vfd speed changes to achieve gapping. Also, the belts are multiple like maybe 3 to 5 with same vfd with encoder. Then the algorithm looks at photo eyes at each belt with tracking file to determine gapping.

This is basically what all do . Seen it enough times.