I have a s1000 system:
A2
Z15 for A7
ground station (2.4G hz)

The current approach is trigger the camera through the Z15 GCU, just like the picture showing:

I was just take photo of terrain for photogrammetry . the Z15 is too heavy, so i don't need a gimbal.
I'd like to trigger camera shutter by A2 F2 PWM channel directly ?
Is there any good suggestion?
if possbile how to connet the A2 and the camera?

These guys have a few products that may work for you. If not I would search around for similar products.
http://littlesmartthings.com/service-accessories/accessories/

Try VP-Systems as well if you are looking for a more intelligent camera controller.

Just connect the proper IR shutter control cable for SONY to the F2 port, map your preferred channel/switch and there you have it.
Are you creating a mount for the camera or using a lighter servo driven gimbal as an alternative?