Position control
Position control or position control refers to the control of the position of a system, e.g. B. a robot axis or a robot. The control of the entire system can be used in service robotics or the control of the end effector z. B. be meant for industrial robots . The structure of the control loop is often a nesting of position, speed and current control loops , see also cascade control
s: position (position), v: speed (speed), a: acceleration, U: voltage, I: current in the motor, PT 1 (red): inductivity of the electric motor, PT 1 (green): mass of motor and machine part
blue - Position control loop
green - Speed control loop
red - Current control loop
gray - Pre-control of the speed and acceleration
The setpoint specifications come from the higher-level position control .
Controller setting
In order to actually be able to operate the drive, sensible settings for the gain of the control loops must be specified or selected. This happens e.g. B. by automatic controller optimization or alternatively by setting values based on experience. Modern methods also allow an adaptation of the parameters z. B. depending on the mass inertia of the system.
When setting the controller, the innermost control loop (current controller) is optimized first, followed by the outer control loops with speed controller and position controller.
In contrast, unfavorable controller settings result in e.g. B. to overshoot the end effector of a robot or to "hum" of the drive. Both are undesirable because they have a negative effect on the travel behavior of an axis or the entire robot.
See also
literature
- Cumhur Baspinar: Robust force and position control of motion- restricted robots with ideal and elastic joints . Shaker, Aachen 2005, ISBN 3-8322-3651-1 .
- Mathias Gutemann: Position control for a responsive actuator unit with an elastic drive train . Shaker, Aachen 2008, ISBN 978-3-8322-7032-2 .