Galil DMC-1700, DMC-1800 user manual Ramped Gearing

An alternative gearing method is to synchronize the slave motor to the commanded vector motion of several axes performed by GAS. For example, if the X and Y motor form a circular motion, the Z axis may move in proportion to the vector move. Similarly, if X,Y and Z perform a linear interpolation move, W can be geared to the vector move.

Electronic gearing allows the geared motor to perform a second independent or coordinated move in addition to the gearing. For example, when a geared motor follows a master at a ratio of 1:1, it may be advanced an additional distance with PR, or JG, commands, or VP, or LI.

Ramped Gearing

In some applications, especially when the master is traveling at high speeds, it is desirable to have the gear ratio ramp gradually to minimize large changes in velocity on the slave axis when the gearing is engaged. For example if the master axis is already traveling at 1,000,000 cts/sec and the slave will be geared at a ratio of 1:1 when the gearing is engaged, the slave will instantly develop following error, and command maximum current to the motor. This can be a large shock to the system. For many applications it is acceptable to slowly ramp the engagement of gearing over a greater time frame. Galil allows the user to specify an interval of the master axis over which the gearing will be engaged. For example, the same master X axis in this case travels at 1,000,000 counts/sec, and the gear ratio is 1:1, but the gearing is slowly engaged over 30,000 cts of the master axis, greatly diminishing the initial shock to the slave axis. Figure 1 below shows the velocity vs. time profile for instantaneous gearing. Figure 2 shows the velocity vs. time profile for the gradual gearing engagement.

Figure 1 Velocity cts/sec vs. Time (msec) Instantaneous Gearing Engagement

DMC-1700/1800 Chapter 6 Programming Motion • 105