Wednesday 28 July 2010

Drive for brushless DC servo motor motion control

New version of drag-and-drop flowchart programmed motion controller with integral servo drive opens market with low-cost brushless servo version

Since its launch in early 2009, Rotalink's Red Drive servo motor driver and controller has significantly lowered the cost barrier for brushed DC precision motion control. Now the innovative designer and manufacturer of miniature motors, transmissions and controls has launched a brushless version of Red Drive that offers the same easy-to-use flowchart based software and price-performance advantages of the brushed version. The new BLDC10A Brushless Red Drive has a 10A input current rating from a 12-24 VDC supply voltage and includes hall sensor inputs for brushless commutation, incremental encoder input and 27 programmable TTL level I/O pins for analogue and digital machine interfacing.

Like its brushed servo counterpart, the modular design concept includes the separately supplied SA1 serial port adapter to program the controller with the free-of-charge Red Drive PC-based graphical software. For fast and cost-effective OEM product development, the microprocessor chip is available separately, allowing the full board version with its integral servo drive to be used in the design and pre-production phases with the IC version incorporated in the final machine for full production. This option also enables the customer the flexibility to choose and design-in the optimum power components and I/O requirements for the application.

This drive is easy to program using a drag and drop flowchart programming method which eliminates the complexity typically associated with many other motion controllers available today. The Windows™ program allows scaling of encoder and gearbox resolution into meaningful units at set-up along with I/O interfacing assignment. Set-up also includes simply entering catalogue values for motor stall-torque and no-load speeds for automatic tuning. Homing, limits and reset inputs can also be set.

The sequential graphical programming format requires little training or specialist motion control knowledge. The programmer simply creates then drags and drops function blocks in a sequential order with relevant values. Separate subroutines can be included in the program to call specific functions at any time on input states or as a part of the program flow. Program functions include incremental and absolute distance moves, acceleration, speeds and wait times in addition to maths and variable calculations. In all, the Red Drive's EEPROM memory storage can handle repeatable sequences of more than 100 functions and drives may be easily linked through I/O for multi-axis set-ups. An A safety input may also be configured to shutdown the drive for emergency measures.

Up to 8 of the 27 I/O points may be assigned to 5V analogue inputs with the remaining available for digital I/O interfacing at 5V TTL levels. All I/O is connected to the BLDC10A via a IDC type connectors using space saving flat cable assemblies or crimp connectors with standard wiring. The 4-pin encoder connection uses a snap-lock header connector, and motor, power and hall sensor connection is via convenient screw terminals. The SA1 RS232 serial adapter board is interfaced via a 14-way header and only needs to be connected to the drive when programming and is therefore useful for production environments or security minded OEM applications where access needs to be restricted.

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