Servo motors came on the scene boasting major benefits for all types of automation, better velocity control, higher positional accuracy, predictable and accurate torque vs speed curves. In short, they delivered. Machines are faster and more accurate than ever, and those companies embracing servo motor driven automation are reaping the rewards.
In recent years, higher resolution feedback has propelled servo driven automation to even better performance.
When a servo motor is in motion, the amplifier is constantly cycling to maintain as close a relationship as possible to the command velocity and position. Monitor the movement with an oscilloscope and you will notice the actual movement is oscillating a small amount above and below the command. In a lower resolution system the servo is being overworked to keep error low with respect to the command. Whe
n increased processing power of the amplifier is coupled with higher resolution feedback, you achieve a much smaller error. Simply put, the motor does not need to work as hard, and is electrically and mechanically more efficient.
Through the years there have been many forms of feedback, resolver, optical encoder, magnetic/hall, and more. Resolutions of these feedback devices typically ranged 1000 – 4000 counts per motor revolution. Newer motors deploy highly accurate, high resolution encoders. A 20 bit encoder has a resolution of 1,048,576 counts per revolution, or a position resolution of 1/1,048,576 of a revolution.
Yaskawa uses 24 bit encoders on the new Sigma 7 Motors allowing up to 16,777,216 counts per motor revolution.
While the need to position to 1/16,777,216 of a motor revolution is rarely a requirement, the wealth of data that 24-bit resolution provides leads to many major benefits:
- Increased system stiffness
- Higher efficiency (optimal commutation)
- Less heat
- Increased stability
- Lower settling time
- Better speed control
- Higher torque to inertia ratio possibilities
High resolution feedback is one of many tools we understand and use to enhance your machinery function and throughput. Contact us today and we’ll get these tool sets to work for you!