Building your own motion control system is quick and easy if you understand the trade-offs involved in selecting the right hardware and software components for your application. National Instruments offers a complete stepper motion solution for a diverse range of applications – including lab automation, machine control, and semiconductor positioning – that is easy to set up, configure, and program. For a stepper motion system, you can follow three easy steps to select your hardware components, configure the system, and develop your software application (see Figure 1).
Figure 1. You can create your stepper motion systems – from selecting hardware to developing the software application – in three easy steps.
1. 1. Select Your Stepper Motion Hardware
First review the following stepper motion control system components, as shown in Figure 2:
- Motion controller – A motion controller takes user-specified target positions and move constraints and creates a trajectory for the motors to follow. NI stepper motion controllers implement a patented algorithm for step generation. With this algorithm, you can average the pulse frequency over multiple time slices, resulting in smoother moves.
- Motor drive – The drive translates the command signals from the controller to current, which causes rotation in the motor. NI offers 1-, 2-, and 4-axis stepper drives with a range of power ratings.
- Stepper motor – Stepper motors are permanent magnet motors that increment one step each time the motion controller sends out one pulse. When stopped they hold their positions. NI offers stepper motors in NEMA 17, 23, and 34 sizes with a range of torque ratings for each size.
- Feedback device (optional) – When used, feedback can correct motion if the motor slips, or you can use feedback for synchronizing motion with data acquisition or vision inspections.
Figure 2. An understanding of the stepper motion control system components can help you choose the hardware and software for your application.
2. 2. Configure Your Motion Controller and Drive
After selecting the stepper motion hardware components, connect them and configure the motion controller and drive. You can directly connect the 2- and 4-axis NI drives to the motion controller using high-density cables and the 1-axis drives using a choice of screw-terminal or D-Sub termination accessories.
Easily configure the stepper drives for a particular stepper motor using the dip switches on the drives. You also can configure the single-axis drives using a serial interface and software. For motion controller configuration and testing, use the NI Measurement & Automation Explorer (MAX) utility.
3. 3. Develop Your Software Application
After you have configured your system, you can begin prototyping and developing your application. For fast prototyping, use NI Motion Assistant to configure and test moves using a point-and-click environment and visualize them with a 3D interface. Finally, generate National Instruments LabVIEW or C code to deploy your application.
This article first appeared in the Q3 2007 issue of Instrumentation Newsletter.