Definition of motion control:
Motion control originated from early servo control. Simply put, motion control is the real-time control and management of the position, speed, and other parameters of moving mechanical parts, ensuring they move according to a predetermined trajectory and specified motion parameters. Early motion control technology developed alongside CNC technology, robotics, and factory automation. Early motion controllers were essentially independent, dedicated controllers, often requiring no additional processor or operating system. They could independently perform motion control functions, other functions required by technological processes, and human-machine interaction. These controllers can function as independent motion controllers. These controllers are primarily designed for specialized CNC machinery and other automated equipment, often with functions pre-designed according to the application industry's process requirements. Users only need to write application processing code files according to the protocol requirements and transmit them to the controller via RS232 or DNC , and the controller can then complete the relevant actions. These controllers often cannot be used across industries without adhering to their specific process requirements; their openness depends solely on the controller's processing code protocol, and users cannot reconfigure their motion control systems according to application requirements.
Motion control system composition
The basic architecture of a motion control system includes :
A motion controller is used to generate trajectory points ( desired output ) and close a position feedback loop. Many controllers can also internally close a velocity loop.
A driver or amplifier is used to convert control signals ( typically speed or torque signals ) from a motion controller into higher-power current or voltage signals. More advanced intelligent drives can close their own position and speed loops for more precise control.
An actuator, such as a hydraulic pump, cylinder, linear actuator, or motor, is used to output motion.
A feedback sensor, such as a photoelectric encoder, a rotary transformer, or a Hall effect device, is used to feed back the position of the actuator to the position controller in order to achieve the closure of the position control loop.
Numerous mechanical components are used to convert the motion of an actuator into the desired motion; these include gearboxes, shafts, ball screws, toothed belts, couplings, and linear and rotary bearings.
Typically, the functions of a motion control system include :
Speed control
Point-to-point control . There are many methods to calculate a motion trajectory, which are usually based on a velocity curve such as a triangular velocity curve, a trapezoidal velocity curve, or an S- shaped velocity curve.
Electronic gears ( or electronic cams ) . This means the position of the driven shaft mechanically follows the position of the driving shaft. A simple example is a system containing two turntables that rotate at a given relative angle. Electronic cams are more complex than electronic gears because they make the follow-up relationship between the driving and driven shafts a function. This curve can be non-linear, but it must be a functional relationship.
How to Choose a Motion Controller
1. Determine the type of servo motor based on the working characteristics of the equipment to be developed.
2. Determine the number of motor shafts to be controlled and the motor operating mode.
3. Determine the position detection and feedback mode, and select whether to use a photoelectric encoder, optical encoder, or magnetic encoder.
4. Determine the number of input/output switches.
5. Based on the above, select a suitable motion controller.
