Mr Sämisch, what exactly is the ArgoDrive system and what advan­tages does it offer in intral­o­gis­tics?

The ArgoDrive system is a perfectly coor­di­nated complete solu­tion consisting of soft­ware, drive control and the ArgoDrive driving steering system. It was specially devel­oped for auto­mated guided vehi­cles and offers omni­di­rec­tional mobility. As a result, AGVs can also move in any direc­tion from a stand­still. Hall foot­prints can be designed very differ­ently, for example, and can often even be smaller because the vehi­cles can maneuver in the tightest of spaces.

This makes intral­o­gis­tics as flex­ible and effi­cient as possible.

Henry Sämisch, Appli­ca­tion Engi­neer Busi­ness Unit Indus­trial Drive Tech­nology ebm-papst

This is possible thanks to the infi­nite steering angle and the 360° wheel of our ArgoDrive driving steering system. This is a compact unit consisting of two brush­less DC motors, a trans­mis­sion, sensors and all the neces­sary connecting plugs. Thanks to the super­po­si­tion gear, the two motors contribute to steering, accel­er­a­tion and travel as well as braking as required.

And what chal­lenges does this pose?

Of course, this places partic­ular demands on navi­ga­tion, control engi­neering, dura­bility, soft­ware and, above all, safety. Any risk of colli­sion must be ruled out. Espe­cially when the area where people work and traffic routes of AGVs converge. That’s why we’ve worked hard on the issue of safety right from the start in the devel­op­ment of our drive system.

How do you rule out colli­sion risks?

ArgoDrive offers several options for reli­able response in any situ­a­tion. For example, if the protec­tive field is breached, the safety control executes the command for a safe stop of the driving steering system. The drives offer high braking power. Up to 2.5 m/s² decel­er­a­tion is possible with the aid of elec­tro­mo­tive brakes. Emer­gency braking can also be carried out in the event of danger. The brake inte­grated in the driving steering system is used for this purpose.

up to 2,5 m/s² decel­er­a­tion

If the power supply of the AGV fails, the ArgoDrive switches to a safe stop, preventing uncon­trolled move­ments. This means that the ArgoDrive supports all typical and neces­sary safety require­ments.

How does commu­ni­ca­tion work in these cases?

To achieve omni­di­rec­tion­ality, an AGV requires at least two ArgoDrive driving steering systems. Each one is actu­ated by two external controllers. The signals for the steering angle are also redun­dant and the posi­tion of the steering angle can be deter­mined at any time. An STO func­tion is also inte­grated, which ensures a reli­able stop. However, the holding brake and Safe Torque Off can also be trig­gered together.

In addi­tion, the drive moni­tors that a certain maximum speed is not exceeded and that the AGV only moves in the desired direc­tion. The rele­vant func­tional safety terms are SLS (Safe Limited Speed) and SD (Safe Direc­tion). The motors have two inde­pen­dent encoder systems as stan­dard: the inte­grated hall sensors for commu­ta­tion and a high-reso­lu­tion incre­mental coder for closed-loop control. By comparing both signals, the elec­tronics can reli­ably record the speed in a func­tional manner. The only prereq­ui­site is that the ArgoDrive driving steering system is correctly imple­mented in the control system of the AGV.

What do we need to bear in mind when inte­grating into AGV and soft­ware imple­men­ta­tion? Is a lot of effort involved in this?

No, inte­grating ArgoDrive into the vehicle is completely straight­for­ward. All parts are compact and safely installed. There are no moving cables.  All-in-one motor cables with indus­trial plugs make elec­trical hookup very easy.

Inte­gra­tion into the control tech­nology is also very easy, as we have already coor­di­nated safety concepts with the well-known compa­nies SICK and Siemens based on the safety indi­ca­tors. This reduces the effort required for imple­men­ta­tion and assembly. And if there are any ques­tions, we are always avail­able as a devel­op­ment partner for AGV manu­fac­turers.

To what extent do the safety concepts of SICK and Siemens differ?

Both concepts have already been success­fully imple­mented in prac­tice. Thanks to pre-assem­bled func­tion modules, soft­ware inte­gra­tion with Siemens can be imple­mented very quickly for all those who already use the SIMOVE control system during the devel­op­ment of an AGV.

How exactly does the safety concept with SICK work?

Depending on which inter­face the High­Level IPC offers in the AGV, the ArgoDrive driving steering system can be controlled via CANopen or EtherCAT. ArgoDrive only needs three spec­i­fi­ca­tions: Command, steering angle and travel speed. In the same vein, ArgoDrive returns the status, steering angle and travel speed. Our hard­ware and soft­ware is respon­sible for the entire control and load distri­b­u­tion.

At the same time, the safety control system performs a cross-check based on the redun­dant sensor signals. This ensures the Safety Limited Speed and Safety Direc­tion func­tions.

What are the advan­tages for AGV manu­fac­turers?

Because our ArgoDrive driving steering system meets all rele­vant safety indi­ca­tors such as MTTFd values, B10 values, perfor­mance level, STO etc. and meets the require­ments of the FTS stan­dards ISO 13849 and ISO 3691-4, it is easier for manu­fac­turers to create their own safety concept. This also simpli­fies the certi­fi­ca­tion of the entire vehicle at the TÜV testing body.