Like so many other fields, there’s no all-singing, all-dancing solu­tion for AGVs and the right vehicle concept has to be found for the condi­tions of the respec­tive appli­ca­tion. With Green­field solu­tions, vehi­cles usually have enough space to maneuver. Retro­fitting existing systems (Brown­field), on the other hand, usually makes the space much tighter and the vehi­cles have to be more maneu­ver­able. It is also impor­tant to take into account the option of fine posi­tioning, for example if the vehicle has to approach and maneuver very precisely.

Further points include the required dynamics when accel­er­ating and braking, as well as the weight of the loads to be trans­ported. What’s more, it must be clar­i­fied how quickly the vehi­cles have to move so that the logis­tics or produc­tion process runs opti­mally. Once such ques­tions about the appli­ca­tion are answered, the manu­fac­turer will opt for a concept. In addi­tion to the vehicle size and battery capacity, the main differ­ences then lie in the number of drive and fixed wheels required as well as their load capacity.

Oper­ating with maneu­ver­able driving steering systems

With the ArgoDrive ebm-papst has devel­oped the right driving steering system including a wheel: for vehicle concepts that require maneu­ver­ability, load capacity, dynamics or the option of fine posi­tioning (Fig. 1). In Light, Stan­dard and Heavy versions, it can move loads of up to 100 kg, 300 kg, or 500 kg per drive unit. The instal­la­tion dimen­sions and the elec­trical, mechan­ical and control inter­faces are iden­tical in all designs. The impeller diam­eter, speed and accel­er­a­tion vary, and the possible load capacity and ground clear­ance also differ. Every drive unit consists of two brush­less DC motors, trans­mis­sion, sensors and all the neces­sary connec­tion plugs.

With the super­po­si­tion gear, the two motors contribute towards steering, accel­er­a­tion, move­ment and braking, depending on require­ments. If the wheel is aligned or no steering move­ment takes place, the entire power of both motors can be used for driving; this makes the ArgoDrive unique. The infi­nite steering angle enables omni­di­rec­tional vehicle move­ment, even from a stationary posi­tion. This opens up many possi­bil­i­ties for vehicle design.

Two- to six-wheel design

If high dynamics and preci­sion are required, in the simplest case a three-wheel design can be imple­mented for a fork­lift truck or a towing vehicle with one ArgoDrive and two fixed rollers (Fig. 2, left). These vehi­cles may not be able to move fully omni­di­rec­tion­ally, but still trans­port large loads extremely flex­ibly, depending on the wheel design, and with a compar­a­tively simple control. A flat design is also possible, as the driving steering system on the driven axle is much more compact than a classic fork­lift drive.

Image 2: More driving steering systems also mean more perfor­mance. (Graphic | ebm-papst)

Image 3: Vehicle typolo­gies with one, two and three driving steering systems. (Graphic | ebm-papst)

If omni­di­rec­tional driving and higher loads are required, two or three driving steering systems help here (Fig. 2, center and right). Partic­u­larly narrow and maneu­ver­able vehi­cles can be achieved with two oppo­site driving steering systems and two fixed rollers. Based on the omni­di­rec­tional driving concept, they can move autonomously and freely navi­gate in produc­tion or in the ware­house, move diag­o­nally into rack aisles and turn on the spot for maneu­vering in even the tightest spaces, to approach transfer stations precisely, for example.

In prin­ciple, the number of driving steering systems used on the vehi­cles can be increased as required. Fig. 3 shows exam­ples of the use of two, four and six Argo­Drives, always expand­able with fixed rollers to increase the load capacity of the vehicle if neces­sary. With four driving steering systems and four fixed rollers, for example, loaded vehi­cles with a total weight of 4 t can be moved extremely dynam­i­cally, omni­di­rec­tion­ally and with high posi­tioning accu­racy.

In Light, Stan­dard and Heavy versions, the ArgoDrive can move loads of up to 100 kg, 300 kg, or 500 kg per drive unit.

Compro­mise between perfor­mance and cost-effectiveness

The possi­bil­i­ties are there­fore virtu­ally unlim­ited. But cost-effec­tive­ness also has to be consid­ered and manu­fac­turers of auto­mated guided vehi­cles have to find the right compro­mise between perfor­mance and cost. This involves checking the perfor­mance require­ments in the appli­ca­tion. Some­times, for example, it makes sense to use just two Argo­Drives instead of four. This cuts the dynamics in half, but the throughput may still be suffi­cient for the end customer because the AGVs would work more slowly in the rele­vant areas anyway. The power consump­tion of the drives can also play an impor­tant role in these deci­sions in connec­tion with the battery capacity.

In such cases, it is advis­able to consult a specialist to be on the safe side. At ebm-papst, prac­tical simu­la­tion tools help to analyze the indi­vidual task and eval­uate various suggested solu­tions (Fig. 4). The calcu­la­tion incor­po­rates all rele­vant para­me­ters from the desired speed and accel­er­a­tion, the required load capacity, the impeller diam­eter and the maximum power consump­tion, right through to the effi­ciency of the overall system. The results help to find the right solu­tion for specific require­ments and thus the optimum compro­mise in terms of cost-effec­tive­ness and perfor­mance.

Easy inte­gra­tion

It is easy for the vehicle manu­fac­turer to inte­grate the ArgoDrive driving steering system in his vehicle, not only mechan­i­cally, but also in terms of control tech­nology. Safety concept and cabling are completely iden­tical for all ArgoDrive vari­ants. All-in-one cables with indus­trial plugs make elec­trical connec­tion easier. This provides a secure, flex­ible and easy-to-inte­grate drive solu­tion for the various types of auto­mated guided vehi­cles, which does not require compro­mises in terms of omni­di­rec­tional move­ment and compact design and is suit­able for use in a wide range of indus­tries.