Three axis servo system cuts space required by 50%

The performance of a typical three-axis servo system can be considerably improved and its complexity and cost substantially reduced with a new servo system.

The performance of a typical 3 axes servo system can be considerably improved and its complexity and cost substantially reduced with Control Techniques' new MultiAx servo system.

The MultiAx is one module with three axes.

Its compact size, combined with Control Techniques unique SLM technology, means that in a typical 3 axes, 10Nm servo system (system including servomotors, motion controller, cabling, switchgear and cubicle), control wiring can be reduced by 45%, cubicle wiring by 60%, material and labour costs by 50%.

Taken together these savings realise the lowest installed cost for the OEM builder, a figure which is 30% lower than a typical system with standalone servo drives.

In addition to providing greater competitiveness overall, the reduction in control terminations and cubicle wiring provided by the MultiAx system results in increased system reliability, while the savings in space from reduced panel wiring, higher axes density (just 92mm for 3 axes) and the (over) 50% reduction in enclosure volume and component count all combine to reduce the overall size of any machine.

The MultiAx has been designed both to improve the performance of multi-axis control systems and to simplify their control, all at realistic cost.

The drive reduces the space envelope required on machines with an extremely compact, integrated module design which features three axes.

Each module operates directly from a 400v 3 phase supply with a common input power stage and braking, three inverter stages with three independent control sections.

For applications requiring more than three axes, additional MultiAx modules can be combined under the control of a suitable multiple axis such as Control Techniques MC Series controller.

The MultiAx provides the OEM with the convenience and benefits of a totally digital control solution.

Much time and cost is saved because, uniquely, there is no requirement for the system builder to undertake the task of programming a motor map into the drive.

This is done automatically by the intelligent encoder which is an integral part of the SLM system.

As a result, the system user is able to switch on the drive system and benefit from excellent performance immediately.

The MultiAx is designed for use as a package with Control Techniques Unimotor SLM and MC series motion controller.

The MC controller is SLM compatible and daughter boards (3 SLM axes per board) can be plugged in.

This is a very flexible arrangement as it enables the user to control 3, 6, 9, 12 or any number of axes.

Added to this, the package of the MultiAx, Unimotor SLM and MC Series controller is optimised or matched to provide optimum performance.

It offers the user a host of advanced functions including Absolute and Relative Position Moves, Linear Interpolation (1-4 axes), Circular Interpolation (2 axes) Helical Interpolation (3 axes) Software Gearboxes, Cam Profiles and Velocity Control.

Key to the market leading levels of performance of this matched system is Control Techniques SLM.

A true digital interface, SLM is a quantum leap forward in servo systems and offers major advantages over existing technology.

It is designed to overcome the limitations of analogue +/-10V interfaces and limited feed back resolution.

The system employs a high-speed, high specification communication network which is used to control a servo drive and servomotor combination.

It employs advanced SinCos encoders to deliver 8.3 million counts per revolution for the speed control loop, achieving unequalled levels of position feedback and precise synchronisation of control loops, irrespective of the number of axes employed.

The user sees these benefits in noticeably smoother performance, faster dynamic response and smaller following errors.

The demands of the SLM system (i.e secure and robust communications) are satisfied by dedicated ASICs, called DriveLink, which are placed in each of the system components (MC Motion Controller daughter board, Unimotor SLM and the MultiAx drive).

The DriveLink implements synchronised fault-tolerant communication between the MC controller and the drive system components via a standard 4-wire RS485 physical layer over cable lengths up to 50m and at data rates of up to 2.5M/bits per second.

It also enables users to optimise on the open architecture of the SLM system by enabling application specific control algorithms or complete control loop structure changes to be downloaded as required.

The deterministic nature of the DriveLink protocol manages three control loops within any axis i.e position interpolator, position/speed controller and the current loop.

It also synchronises individual axes to a primary trigger, and the complete multiaxes system can be accurately captured to within a 50 nanoseconds jitter.

In addition to comprehensive axis control features, the package of MultiAx, Unimotor SLM and MC Series motion controller can easily be integrated into a wider factory automation system and is the ideal OEM solution for competitive automated machinery.

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