Difference between revisions of "Control modes"

Revision as of 12:05, 19 April 2012

There are three main control modes in motion & motor control are torque, velocity and position control.

Torque control

Torque

Torque control mode makes motor a torque or force transducer. I.e. user sets torque reference to 1 Nm, then motor will produce 1 Nm torque regardless of spinning speed. In torque mode user can not set limits to velocity or position.

Typical applications

• Racing/flight simulators
• Feeding/pulling
• Cascaded controller after velocity or position controller
• Non-motion applications: high current LED & Peltier driver when drive used just as adjustable current source

Velocity control

Velocity

Goal of velocity control is to regulate motor speed. I.e. if user velocity reference is 500 rpm, then motor attempts to rotate exactly at 500 rpm no matter how much load is attached to motor. In velocity mode user can set limits for torque but not for position.

Typical applications

• Screw tightening robot when used with torque limit
• Spindles
• Feeding
• Fans & pumps
• Position control when used with external or internal position controller

Position control

Position

Position control mode attempts to provide precision positioning. Motor follows reference set point and if set point is kept constant, motor holds position even if external forces attempt to displace it. In position mode user can set limits to torque and velocity.

Typical applications

• CNC
• Pick & place machines
• 2D/3D printing
• Robotics