29 www.drivesncontrols.com October 2026 MACHINE BUILDING n A smarter approach to simpler motion architectures For a typical 1kW axis, a cable with a run of around 15 metres can represent nearly 20% of the total cost of the axis. This is compounded by the fact that unlike the drive and motor, the cost of cables climbs steadily with current and distance. Larger currents mean more copper, and longer runs add up quickly across multi-axis machines. These factors change how we need to think about “simplifying the cabinet.” It is not an exercise in tidiness. If approached deliberately, rather than by default, simplifying a machine's wiring and architecture is one of the most powerful levers an engineer has, and recent advances in drive technology have only increased the opportunity. We can start by examining the connection between a single drive and its motor. For a brushless servomotor, the classic arrangement is to use two cables. One carries power from the drive to the motor. The other carries feedback – the encoder or resolver signal that reports the rotor position back to the drive, allowing the motion to be controlled. If the motor has a holding brake, that adds its own wires. In recent years, digital feedback devices have changed the picture. Rather than running a separate feedback cable, modern position sensors communicate digitally, combining the encoder’s power and its position data onto a few wires. That makes it possible to carry power, feedback and brake control together in a single hybrid cable. The payoff is immediate. One cable instead of two means fewer connections to terminate, faster commissioning, and less wiring to route, label and protect. The cable diameter may be a bit larger, but rarely enough to matter. And because a hybrid cable replaces two separate runs, its cost can be reduced by almost half. Kollmorgen’s AKD2G drive, for example, is based on this approach, and uses a singleconnector, single-cable technology, so that the wiring between the cabinet and a machine comes down to one run per axis. Rethinking where the drive sits Single-cable wiring simplifies the link between a drive and its motor, but the drive itself still lives in the cabinet, with a cable running out to the machine. A bigger opportunity lies in questioning that layout altogether. Instead of a cabinet packed with standalone drives, modular systems (such as Kollmorgen’s MKD) use a central power supply that creates a shared DC bus. The drives can sit inside the cabinet next to it, or – more interestingly – they can be mounted on the machine itself, close to the motors they serve. These “nearby” drives connect back with a single cable that carries both DC bus power and the fieldbus signal that tells each drive what to do, and they daisy-chain from one drive to the next. The effect on cabling is dramatic. Picture a machine with ten motors. The conventional approach would be to put ten drives in the cabinet, each with its own cable out to a motor. This requires perhaps 20m per cable, resulting in a total requirement for 200m of cable. By contrast, when drives are distributed on a machine and daisy-chained together, a single run leaves the cabinet and hops from drive to drive. The quantity of cable you need is dramatically less – around 30m in total. Of course, simplifying cabinets can offer benefits beyond cutting down on cables. Wellplanned designs can simplify maintenance, reduce the risk of component failure, and cut installation times. Beyond this, there’s also the fact that moving drives onto the machine shrinks the cabinet – and cabinet space is rarely free. After all, an end-user buys a machine because they need the machine; the cabinet is just something else that they then have to find room for, and in an existing plant that can be a real headache. A smaller cabinet – small enough, in some cases, to be mounted on the machine itself, rather than next it it – means the installation needs little more floorspace than the machine’s own footprint. There is a longer-term benefit too. Machines are often expanded after they have been installed, with extra axes or options being added a few years down the line. When everything is wired back to a central cabinet, that usually means opening up the cabinet, finding space, and rebuilding part of the wiring – work that takes the machine out of use while it is being done. With distributed drives on the machine, a new axis can often be added by taking the signal from the last drive in the chain and making a single connection to the next. The machine can be designed to grow, with far less disruption when it does. It’s important to note that there is no such thing as a universal “best” architecture. A standalone drive with a hybrid cable is the right answer for plenty of machines, while a modular, decentralised system earns its keep where axis counts are high or cabinet space is tight. The point is that wiring and cabinet layout deserve to be treated as design decisions in their own right – made deliberately, against the real demands of the machine, rather than being an afterthought, or inherited from the way the last system happened to be built. Approached in this way, simplifying cabinets can soon become a practical route to lower costs, smaller footprints, quicker commissioning, and machines that are easier to live with for years after they ship. n When designing motion systems, a great deal of attention goes into choosing the right motors and drives. Far less tends to go into what connects them, or where the drives are placed. Yet these decisions shape much of what ultimately matters about a machine – what it costs to build, how much space it needs, how quickly it can be commissioned, and how easily it can be adapted later. Nicola Pezzolato, Kollmorgen’s application and commercial engineering leader in the EMEAI region, explains. Mounting drives on or near machines can cut costs, save space, and speed up commissioning
RkJQdWJsaXNoZXIy MjQ0NzM=