1. Design for system. It is important to understand the accuracy requirements of the entire electromechanical system when specifying servo drives. The control system, position feedback sensing, the drives and final gears/mechanical links have to be carefully chosen to work together so that the desired resolution of control can be achieved. It is important to work with suppliers who strive to understand your needs and will provide knowledgeable technical support when complex control strategies need to be implemented.
2. Plan for surprises. If you've ever designed motion control systems or served as a project manager, chances are you've run into a few surprises during a project, such as over-running conditions, inertia, braking and deceleration, current dissipation, back driving or on-site drive tuning - just to name a few of the more common issues associated with motion-control design. You're the person responsible for ensuring you have thought of everything when dealing with motion-control concerns. So instead of charging full force into a project, take the time to first identify all the possible scenarios that your project may face before it starts. It's important to document potential trouble spots and anticipate appropriate solutions.
3. Exceed machine specifications. The problem with motion control is that speed does not necessarily equate to throughput and motor resolution does not equate to system accuracy. You need to design the system to exceed the machine specifications; this means from the drive point back to and including the motor.
4. Cubic splines. Use cubic splines for motion planning and for servo Interpolation of position, velocity and acceleration.
Don't forget power, grounding
Proper system design is critical to the long-term success of your manufacturing system. Steps to remember include:
- Power monitoring for energy management.
- Balanced and adequate power distribution for immediate needs (in current and voltage range), as well as an allowance for growth.
- Power supply review for variable frequency drives, inverters and converters to ensure adequate isolation, impedance and grounding.
- Grounding review for supply to drives, drives to motors, motors to supply for high-frequency mitigation, as well as safety or PE (potential earth) and adequate isolated TE (true earth grounding) for control and communications.
- Cable selection, routing, management and access design.
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