close the position and velocity loops internally, resulting in much more accurate control. A prime mover or actuator such as a hydraulic pump, pneumatic cylinder, linear actuator, or electric motor for output motion. In closed loop systems, one or more feedback sensors such as absolute and incremental encoders, resolvers or Hall effect devices to return the position or velocity of the actuator to the motion controller in order to close the position or velocity control loops. Mechanical components to transform the motion of the actuator into the desired motion, including: gears, shafting, ball screw, belts, linkages, and linear and rotational bearings. The interface between the motion controller and drives it control is very critical when coordinated motion is required, as it must provide tight synchronization. Historically the only open interface was an analog signal, until open interfaces were developed that satisfied the requirements of coordinated motion control, the first being SERCOS in 1991 which is now enhanced to SERCOS III. Later interfaces capable of motion control include Ethernet/IP, Profinet IRT, Ethernet Powerlink, and EtherCAT. Common control functions include: Velocity control. Position (point-to-point) control: There are several methods for computing a motion trajectory. These are often based on the velocity profiles of a move such as a triangular profile, trapezoidal profile, or an S-curve profile. Pressure or Force control. Impedance control: This type of control is suitable for environment interaction and object manipulation, such as in robotics. Electronic gearing (or cam profiling): The position of a slave axis is mathematically linked to the position of a master axis. A good example of this would be in a system where two rotating drums turn at a given ratio to each other. A more advanced case of electronic gearing is electronic camming. With electronic camming, a slave axis follows a profile that is a function of the master position. This profile need not be salted, but it must be an animated function See also Match moving, for motion tracking in computer-generated imagery Mechatronics, the science of computer-controlled smart motion devices Control system PID controller, proportional-integral-derivative controller Slewing Pneumatics Ethernet/IP High performance positioning system for controlling high precision at high speed External links What is a Motion Controller? Technical Summary for Motion Engineers Further reading Tan K. K., T. H. Lee and S. Huang, Precision motion control: Design and implementation, 2nd ed., London, Springer, 2008. Ellis, George, Control System Design Guide, Fourth Edition: Using