Gripper Integration
This document describes how to integrate the gripper
Last updated
This document describes how to integrate the gripper
Last updated
Grippers are a commonly used mechanism for UAV delivery applications. Although there are multiple types of interfaces (e.g. PWM, ) for different products in the market, the most commonly used interface is PWM. The integration of PWM controlled gripper hardware is explained in the following section.
For grippers actuated via PWM signal, the cabling comprises of three lines: Power, Ground and Signal. A typical connector is shown in the image below:
In the image above the wire colors have the following meanings:
Brown
Ground
Red
Power
Yellow
PWM Signal
Before proceeding, double-check the following requirements:
Make sure to connect the ground and signal pins correctly to the adapter board and rely on the G-V-S labels printed on the PCB.
This is done by using one of the PWM pinouts to connect to the power source via the Power and Ground lines.
Above is a copy of the Auterion PX4's pre-existing gripper mixer (gripper.aux.mix). As indicated by its name, this mixer is only available on AUX outputs.
To enable this mixer, add the following line to your airframe file. This will automatically utilize the gripper.aux.mix file and load it as a AUX mixer:
With the above setting, AUX1 pin will provide the PWM (1000 ~ 2000 us Pulse-Width) output for the Gripper mechanism.
Here is an example of a custom mixer and airframe file that will use AUX3 as an output for the Gripper mechanism:
Although mentioned above already, there are 2 crucial steps to getting the mixer loaded properly and working.
Signal line voltage level: Check the datasheet of your gripper mechanism to find the voltage level of the signal line. And make sure this is compatible with the voltage level of the pins, exposed on the Pixhawk Adapter Board. As of writing, the FMU pins have 3.3V logic level, so gripper should not drive the signal line above 3.3V!
Power requirements of gripper: Check the mechanism's datasheet for the power-line voltage level requirements. Based on the voltage the gripper can be either connected directly to the and use the battery voltage, or connected to a separate 5V line. Alternatively a custom voltage regulator can also be used to output any other voltage required.
If your gripper mechanism receives power through the power line of PWM cable (which is the most cases), you must supply the power to the Power line of the PWM pinouts of the Pixhawk Adapter Board from the source chosen as .
AUX refers to the output from the FMU controller rather than the IO controller. For more information, refer to the .
In case you want to use a different pin than AUX1, or a MAIN output for gripping mechanism, you will need to modify the mixer yourself. Take a look at the section on to see how.
Then modify the mixer and airframe files accordingly to map the delivery mechanism to the correct output. For further information visit the for understanding how summing mixer works, the mixer needed for the gripper mechanism.
The mixer needs to be loaded in the airframe file as described in .
And then it must be uploaded to the vehicle as described here: .
