The Distance Orientated Speed Profiler (DOSP)
Fast, accurate stopping is a requirement for high throughput machine operation. However, it is rarely a feature of conventional control software. With 22 years experience in the control industry, Electronic Innovations′ solution to the requirement is the Distance Oriented Speed Profiler (DOSP).
Background
The typical approach for repetitive motion uses the following sequence:
- Accelerate to and coast at a constant speed.
- Decelerate to creep speed, as the material nears its destination.
- Maintain creep speed until the destination is reached.
DOSP
The DOSP position control modulates a torque setpoint of a motor drive unit, based upon the distance from the destination. The required torque is calculated by a software control module using encoder position and speed feedback. The typical method of using a speed setpoint that varies with time allows any speed error in the controller to generate an accumulating position error in the result. The DOSP method causes no accumulating error and can therefore accurately reach zero speed at the correct distance. DOSP applies an adaptable deceleration method nearing a destination, allowing a variety of approaches to a destination. Thus, it will operate with any combination of acceleration, deceleration and top speed, whilst still providing a controlled accurate stop at the desired destination.
Implementation
DOSP is implemented as a software module on Electronic InnovationsŐ microprocessor based realtime controller. The controller runs a number of modules, including an advanced software speed control loop incorporating modes that allow rapid settling and/or true synchronising position error control. Combined with the DOSP algorithm it achieves the fastest possible movement, whilst maintaining machine safety and accurate stopping position.