PreciseFlex_Robot
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position of the gripper. The Linear Axis appears as Joint 6 in Joint Coordinates and in the Virtual Pendant
Coordinates. It may be moved by the “Move.OneAxis” command by selecting Joint 6.
The factory test program which is shipped with each robot includes sample code to move the Linear Axis.
Controlling the Precise Servo Grippers
Overview
The 23 Newton Precise Servo Gripper with spring return contains a brushless servo motor with an
incremental encoder with both counting and motor phase tracks. At power up the encoder provides motor
commutation information for a brief period, and then switches the incremental encoder A, B and Z signals
onto the same set of wires. This allows the motor commutation to be initialized at startup without any
motion.
The motor has a 12 tooth pinion gear cut directly on the motor shaft. This pinion drives a pair of opposing
racks to open and close a set of finger mounts which are attached to linear ball slides. Various fingers
can be attached to the finger mounts.
One finger mount is also attached to a spring return, which applies a continuous closing force to the finger
mounts as they are coupled together by the pinion. So if power is lost the gripper will close and maintain
a closing force so that it does not drop parts.
In order to avoid the gripper slamming closed from the spring force when motor power is disabled, there
is a 500ms delay after an EStop or power disable command is sent before the motor power is cut off.
During this period, the servo slowly closes the gripper.
In order to support “free” mode, in which the fingers can be moved back and forth freely by hand, in free
mode the servo counterbalances the spring by applying an opposing force based on finger position.
For the 3kg PF3400 users may order an optional 60 Newton servo gripper.
Software Revision
The Spring Gripper functionality is fully supported by GPL version 3.1.P11 or later and PAC files
PFlex400S_Prod_B03 110913 or later. Some slightly earlier software versions were delivered to beta
customers.
Controlling the Gripper
Precise has created a GPL software routine that controls the spring gripper. This routine includes
features for controlling the gripper squeeze force and detecting if a plate is present during a grip. Precise
makes this routine available to customers upon request. This routine is also available in the Precise
Command Server Software for the PF400.
Gripper Squeeze (Simple Method)
The spring applies a closing force of approximately 7 Newtons at a finger opening of 103mm, which is
halfway between a portrait titer plate grip at 83mm and a landscape titer plate grip at 123mm. The force
is closer to 6N in portrait mode and 8N in landscape mode and 9-10N at the full open homing position.
These closing forces appear adequate to prevent dropping titer plates weighing up to 200 gms, and are
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