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Stepper expertise for spiral plater system

Edited by the Engineeringtalk editorial team Sep 21, 2000

SmartDrive has developed an integrated control system for the WASP spiral plater, used extensively in the food industry to test for safe levels of bacteria, developed by Don Whitley Scientific

SmartDrive, the Cambridge based developer of stepper-motor drivers and controllers, has developed an integrated control system for the world-beating WASP spiral plater developed by Don Whitley Scientific.

The WASP unit is used extensively in the food industry to test for safe levels of bacteria, as well as in the pharmaceutical, cosmetics and water industries.

The spiral plater method eliminates the requirement for serial dilutions, saving time, labour and laboratory materials.

To achieve these savings while upholding strict quality regulations, precise control of all motion axes is required, including axis interpolation.

In the spiral plater system, a stylus arm with a stepper-driven syringe is used to dispense liquid samples in an Archimedes spiral, either uniformly or as a continuously decreasing volume across a stepper-driven revolving plate.

Pre-programmed options allow liquid samples to be dispensed in a variety of ways, and self-clean motion can be initiated at the touch of a button.

For each Wasp plater, SmartDrive produces a unique 'black box' subsystem, the design of which was a joint effort with the customer's machine development engineers so as to provide the optimum integration and cost-effective production.

A simple folded steel housing contains all the electronic parts, including a toroidal transformer and EMC filtered IEC mains inlet, a 4-axis motion controller card and a 3-axis microstepping drive card.

The cards are plugged into a backplane incorporating power-supply components with a driver for a small DC servo and interfaces for the several sensors.

A specially developed RS232 serial connected membrane keypad interface circuit board, which also carries LEDs to illuminate program-selected key positions through the membrane, provides the operator interface to control the machine.

All interconnections to devices in the machine are made by plug and socket to give rapid first-level servicing.

Within the housing, the electronics is modular for easy second-line servicing.

With all the electronics being built and tested by SmartDrive as a fully integrated subsystem with hardware and software support, Don Whitley Scientific has been able to concentrate on their prime expertise in the areas of laboratory equipment design and microbiology.

Cambridge based SmartDrive Ltd is the leading UK designer of stepper-motor drivers and controllers.

The company's wide range of Eurocard-based products are used in motion control systems in many industries from pharmaceutical through to more traditional engineering.

Customers like Don Whitley Scientific often have unique system applications, and SmartDrive is called on to provide custom solutions to meet specific operational and packaging requirements.