Robotics turn to digital motor feedback interface

Supplier: SICK Sensor Intelligence By: Bernd Appel, Head of the Motor Feedback Systems Business Unit, SICK STEGMANN GmbH, Donaueschingen, Germany
16 April, 2018

The HIPERFACE DSL® digital motor feedback interface has been on the market for over five years now.

During this time, it has ushered in a technological revolution in many fields of electrical drive technology, particularly with regard to Industry 4.0 and condition monitoring. More and more, its effects are being felt in robotics and handling technology too. With this in mind, KOLLMORGEN Europe GmbH also offers this secure communication protocol in its motion packages for robots designed for use in a range of applications, including those with stringent motion control requirements.

We are in exciting times for the field of robotics. While around 90 percent of all robotics applications are currently of the coexisting or cooperating type, in future human-robot collaboration is set to increase its present share of roughly 10 percent quite significantly. At the same time, the robotics market is expected to grow – driven among other things, by Industry 4.0 and the transition to flexible working processes, as well as the new opportunities being opened up by machine condition monitoring. “The HIPERFACE DSL motor feedback interface is extremely well suited to robotics drive systems simply because it employs purely digital data transmission,” says Dr.-Ing. Petr Osipov, Motors Product Manager at KOLLMORGEN Europe GmbH. “But on top of that, it requires minimal connections between the servo amplifier and the motor feedback system, plus it allows for reliable and interference-free communication between the drive and the motor.” What’s more, other specific benefits come into play whether it is used in classic types of robot, in collaborative robots (known as cobots), or in handling systems with mobile machine structures.

KOLLMORGEN Europe: extensive experience in robotics drive technology

KOLLMORGEN, which in 2016 celebrated its 100th birthday, is a leading provider of integrated automation, drive systems and associated components for machine manufacturers worldwide. The company's vast experience in motion control design and the development of standard and specialised solutions benefit machine manufacturers in many industries, including foodstuffs, packaging, printing, metalworking, and medical technology. With over 1,300 employees all over the world, KOLLMORGEN continues to develop innovative solutions that are distinguished by their performance, quality, reliability, and ease of operation. “KOLLMORGEN first got involved with specialised motors and drive solutions many, many years ago,” reflects Dr.-Ing. Petr Osipov.

Since then, the company has created a range of innovative motion packages with digital one-cable solutions, which can be used very successfully in the field of robotics too. “Alongside Hiperface DSL, we also offer our own reliable and cost-effective SFD encoder solution,” says the KOLLMORGEN product manager. “It is basically a resolver, whose electronics convert analogue signals into digital protocols.” The motion packages are based, among other things, on servo motors from the AKM product family and AKD servo controllers; they provide high power and torque density and have impressively low wiring requirements. Featuring HIPERFACE DSL® motor feedback systems, they meet the most stringent demands in terms of resolving feedback signals; such high standards are necessary for the precise motion control and positioning of robots or in high-speed applications, for example.

One-cable technology in robotics: special benefits regarding construction...

Generally speaking, one-cable technology offers a number of benefits in machine building. Just one single motor cable is all that's needed. This reduces the cabling effort by half, as one encoder cable set, two plug connectors, and all the associated cabling work are no longer necessary. “This is an important factor in an industry experiencing particular cost pressure,” says Dr.-Ing. Petr Osipov. The resulting reduced installation work provides the advantage of having fewer potential fault sources and thus, a significantly reduced risk of technical problems. Finally, digital motor feedback opens up the possibility of communicating with, querying, and monitoring the drives right from the control.

One-cable solutions such as HIPERFACE DSL® offer many great additional benefits specific to robot manufacturers as well. The lack of a cable and all its associated connections reduces the weight of the unit, saving kinetic energy as a result. Dr.-Ing. Petr Osipov explains that “There is also the fact that, under certain conditions, drives can be designed to be smaller, more space-saving, and more energy-efficient – all without causing the robot to lose any power. Depending on how many drives are running in a robot with one-cable motor feedback systems, drive technology as a whole can become much better value for the manufacturer at the end of the day.”

This downsizing also feeds into the trend visible in many fields, including robotics for even more compact machines, which the end customer is able to install even where space is at a premium. Another construction-based benefit is the simplified cabling to the moving components. The design of the HIPERFACE DSL® digital interface is responsible for this, facilitating as it does with the hybrid cable with a cross-section that is smaller than ever before. At the same time, it is available in versions that offer torsional behaviour and that are better suited for use with mobile cable handlers.  Thus ensuring optimum freedom of movement for power machine structures. The thin cable can be routed right up to the outer actuators or gripper elements in a way that saves both space and weight. This also helps to keep the cable assembly created in the robot as narrow as possible so that cables can be routed either along or inside the robot’s structure in an ideal manner.

... connectivity and condition monitoring

Another benefit of HIPERFACE DSL® in the field of robotics is digital signal transmission. Digital unlike analogue, is immune to noise and, as such, offers maximum security against the effects of the machine environment. This is one of the fundamental requirements that must be met to ensure that the motor and drive can communicate free of faults and interruptions. Thus making condition monitoring of motors and drive axles possible. “Digital one-cable motor feedback provides the option of recording a range of motor data in the form of histograms, which allows you to identify interference factors and causes of damage quickly,” explains Dr.-Ing. Petr Osipov. “Motion profiles, operating hours, motor temperature, current consumption, speeds, velocities, and the respective changes to these variables enable statements to be made about the current status and likely future development of drive and machine conditions; this information can then be used in the context of continuous condition monitoring for diagnostics and preventative maintenance.” Aided by the functionality of the electronic type label, motor characteristics, serial numbers, part numbers, and other data. These provide rapid assistance in the event of service or replacement work and can be transferred via HIPERFACE DSL®. Condition monitoring via motor feedback systems optimises robot and handling system availability. At the same time, it creates great potential for saving operating costs, as machine elements do not have to be subjected to cyclical checks and preventative replacement, and instead their possible operating time can be utilised to the full.

Motor feedback systems with HIPERFACE DSL® for all types of robot

The HIPERFACE DSL® digital motor feedback interface opens up an incredibly broad range of benefits and innovative potential for robotics in connection with Industry 4.0 and the “smart factory”. Thanks to SICK Stegmann’s wide variety of motor feedback products, this still applies no matter what type of robot is being used or what requirements it has to meet. For articulated-arm robots, there are rotary motor feedback systems from the EKS36 product family with 20-bit single-turn resolution on the one hand, and EKM36 with an additional 12-bit multi-turn functionality on the other. Their space-saving construction fits perfectly into a compact robot design. Regarding safety, they are suitable for applications up to SIL2 in accordance with IEC 61508. Articulated-arm robots with large hollow-shaft or torque motors and SCARA robots too – often feature the SES/SEM70 or SES/SEM90 rotary motor feedback systems, which are installed flat and provide 64 sine/cosine periods per revolution and a mechanical 12-bit multi-turn. Their hollow shaft design means that cables can be routed internally for both types of robot, which is important if they are to be used collaboratively.

When it comes to Cartesian coordinate linear robots, the portfolio has ideal solutions for absolute length measurement and position determination in the form of the TTK50 and TTK70 linear motor feedback systems. They are completely wear- and maintenance-free, thanks to their non-contact measurement principle. Further plus points are their suitability for traversing speeds up to 10 m/s and for use in harsh operating conditions. The EKS36 and EKM36 compact and high-resolution motor feedback systems are also proving their worth in delta robots, which are employed in highly dynamic pick & place applications, among others. The product range is currently being expanded to include motor feedback systems with a capacitive operating principle, with the addition of the EES/EEM product families for collaborative robots with direct drives, plus SES/SEM with hollow shaft diameters of 25 mm and 50 mm.

Platform for intelligent communication with all axes

For quite some time now, HIPERFACE DSL® has been much more than “just” the leading digital motor feedback platform; it is also a technological springboard into the future. With sHub®, SICK Stegmann is working on a multi-sensor concept which makes electrical drives even smarter, as the additional sensors provide new information for even more intelligent maintenance concepts. This opens up the possibility of separating control-related and maintenance-related data, so that the maintenance data can be made available as histograms for condition monitoring in the cloud via Bluetooth or NFC (near field communication) gateways, for example. Bit by bit, getting closer to the goal of achieving intelligence in all axes...