CAMs allow users freedom to create their own motion profile dedicated to the application requirements. All Motion Coordinators have very powerful and flexible CAM commands which make possible applications that can be impossible to construct without these facilities.
Motion Coordinators have a memory TABLE in which CAM profile shapes may be constructed. The size of the TABLE varies between 16000 points on the MC302X and 250,000 points on the MC224. The CAM profile shapes can be constructed offline, or built by the Motion Coordinator itself, or imported from programs such as Excel. Trio provides a very useful CAMGEN utility for helping with the construction of CAM profile shapes.
Motion Coordinators provide two fundamental types of motion command for using the CAM profile shapes. These allow a CAM to be executed over a flexible timebase or as motion linked to another machine motion. The CAM shapes can be used in a very flexible way, for example they can be stretched as they are used, and the controller can choose to use just a portion of a larger shape. There are controls too to allow flexible repeating of CAM shapes.
These controls allow profiles to be executed backwards and forwards to allow the Motion Coordinator to simulate mechanisms which can be run in either direction. There are also controls to allow the starting of CAM’s on a registration event or when a machine position is reached. For complex applications, multiple CAM shapes can be merged together in a seamless way.
Motion Coordinators are designed from the ground up to support motion applications with continuous motion in one direction. In such applications as printing, and flow wrapping the machine is required to remain under precise position control whilst acting in some ways as just a speed axis.
The Motion Coordinator allows for endless motion axes which will “wrap” their axis positions either automatically or at a time to suit the application program. This shifting of the frame of reference of the axis can occur during moves and at full speed. “Virtual” axes can be defined in a Motion Coordinator.
A virtual axis is an axis that is provided for the convienience of the programmer. They may be used for example to superimpose an advance or retard move on to a continuous motion in a very simple way.
Coordinate transformations allow a machine to be programmed in a “Frame” which does not correspond one-to-one with the machine axes. An example of a very simple coordinate transform is given in the diagram. In this class of “single belt” machine, two stationary motors are used to produce X-Y motion. However if the motion required is in the Y direction both motors must move in opposite directions. For motion in the X direction the motors must move in the same direction. Frame transformations are commonly used with “robots” but can be useful in a much wider variety of machine types.
A Motion Coordinator can have alternative “frames” installed which are dependant on the geometry of the machine being controlled. Some common transformations are available “off the shelf”. Alternatively for more unusual machines frame transformations can be easily added and linked to the standard Trio software using the ‘C’ language. Please contact your Trio distributor if you need to do this.
Motion Coordinators provide functions to make applications such as synchronised flying shears easy to implement. The conveyor being synchronised to need not be under control of the Motion Coordinator. There are 3 types of "linked" moves available.
Flying shears are typically implemented with a pair of MOVELINK commands. The MOVELINK gives the position synchronisation required and can be programmed to start very accurately relative to a position on the conveyor.
Electronic gearboxes allow a Motion Coordinator to simulate the motion that might be mechanically performed using a gearbox. Electronic gearboxes are the simplest type of “linked motion” that Trio Motion Coordinators can execute. With “linked motion” a motor axis is program linked to the measured position of another axis rather than using a timebase. Constructing gearboxes electronically is easy and offers great flexibility to machine builders.
Synchronisation can mean many things in motion control. From coordinated movement of two or more axes in position lock, to triggered motion from an external event, to linking an axis to a reference in applications such as flying shears, winders and conveyor synchronisation.
A common requirement is to synchronise motion by triggering from an external event or position. In applications such as the labelling machine illustrated, how the Motion Coordinator handles synchronisation is critical to the performance of the machine.
There are 2 steps to the synchronisation process. Firstly the Motion Coordinator is able to capture the position of an axis using electronic hardware via 2 axis inputs. This capture process can occur in around 1usec or less (dependant on controller type). Secondly, although the Motion Coordinator works with a fixed update cycle, (normally 250usec/500usec/1ms) and is unable to take action until the next cyclic update. It can be programmed to execute moves, or dwells, as if they started exactly when the sensor was triggered.
Interpolation is the process where multiple axes work together to move an end point along a path defined in more than one axis. When performing interpolation, the Motion Coordinator calculates the “path speed” and works at the programmed speed along the interpolated path using Pythagoras’s theorum. Groups of axes cooperate in a “group” working with the velocity profile from a single axis known as the “base” axis of the group.