Does size really matter?

UK-based Wyko Industrial Services is launching what it thinks might be the world’s smallest SERCOS compatible servo system at Drives & Controls 2002.

Measuring just 50mm, the compact Sanyo Denki PV servo system, together with its AML software based controller, provides a solution for systems requiring up to up to 32 axes of tightly co-ordinated servo motion.

Wyko says the new servo system is ideal for applications such as packaging and printing, where noise free, deterministic multi-axis control is essential – and size – really does matter.

Despite their size, the PV series servo systems offer capabilities for electronic camming and gearing, registration correction, programmable limit switches, event handling, homing, jogging, absolute and relative motion, timing and control of analogue and digital 1/0.

In addition, the PV unit closes all control loops internal to the drive and offers the facility for position commands to be provided with 32 bit accuracy from the controller at up to 1,000 times per second.

The PV Servo Systems are fully-digital units with an integrated design that ensures that the only connection required from the controller to the PV drives is a noise-free, fibre optic cable. The determinism resulting from this connection medium means that the AML controller can be up to 250 feet from the drive without any signal loss. An additional benefit is that the fibre optic interface replaces the many logic connections required in a traditional servo system, saving both time and money.

The task of setting-up and operating up to 32 SERCOS based PV series servo systems is simplified by the AML productivity suite for Windows, and, at plant level by a universal remote operator that allows setting of servo drive parameters and the checking of the servo status. The AML package is suite of development and toolbox software that allows configuration of SERCOS compatible servo systems and the creation, debugging and maintenance of AML application programs.

Importantly, programs created using the Windows compatible software are configured to enable all drive parameters to be accessed, using SERCOS identification numbers (IDN’s). This ensures that the PV drives can work with AML or other SERCOS compatible controllers.

The ability of the PV series to reduce costs, via simplified set-up, is further optimised when the requirement is to house the servo drive in a control enclosure. In these cases, the built-in functionality of the PV drives simplifies the panel design by minimising the need for additional external components. To illustrate this, dynamic braking, a holding brake, timing control and a built-in regeneration circuit to handle excess energy during motor speed reversals, are all standard functions, together with high-speed registration inputs. The latter are included to latch motor position, passing this data to the axes controller, which uses it to correct for inconsistencies such as film stretch or other variables.

CE marked and manufactured in an ISO-9001 facility, the PV family of drives includes seven models rated from 100 W up to 1.5kW, with peak torques of 0.97Nm and 20Nm, respectively, all offering operation up to 4,500rpm. All the models operate from a single-phase 230 VAC input supply and a feature of the design is that this supply is separated to provide discrete inputs for the Main and Control Power. This allows the main (motor or ‘bus’) power to be disconnected during an alarm or emergency stop situation while retaining the control (or logic) power for fault analysis and retention of position feedback.