MbPro Gripper
From Merlin Systems Wiki
Miabot Pro gripper accessory TODO: pictures, descriptions
NOTE owing to its power requirements, the gripper attachment can normally only be used with the Gripper/Expansion board accessory.
Documentation
Commands
From version 2.6, the standard robot software has an extra command to control pulsewidth outputs to drive standard servos.
The command ‘P’ takes a sequence of decimal values which determine the outputs, up to the number of servo outputs.
The control values can be in the range 0-255, giving an output pulse length of 1.0-2.0 mSecs nominal.
E.G.s
- “[P 0 85]” puts the gripper open, and in a horizontal position
- “[P 0 150]” puts the gripper open, and in a raised position
- “[P 255]” closes the gripper
There are also two control parameters which affect the servo output behaviour . . .
[.ebP] controls which pwm outputs are used
Up to five outputs can be supported, where each output is enabled by setting the appropriate bit in .ebP :–
output bit EXP signal EXP connector pin ------ --- ---------- ---------------- 1 0 A2 11 2 1 A3 9 3 2 A4 7 4 3 A5 5 5 4 A1 13
NOTE: output#5 is not compatible with use of the I2C bus.
For the normal gripper setup, outputs 1+2 are connected to the gripper and elevator
servos (in that order), and .ebP=3 (or more).
[.PDT] controls the startup pulse output delay
This is needed because controlling the servos while power is applied causes uncontrollable chatter (interaction with power-supply current limit).
Currently set to 100 (=milliseconds), which seems to work. This should never need to be changed.
