Is there a way to turn off the Vdd on the USB connectors

[dagbay]

I am working with USB devices that are used in Radio telescopes. The devices use a PIC micro-controller which is designed to sleep to minimize the clock noise unless a hardware error occurs or a host connects to its USB input. The MCU senses the Vdd on the USB connector as an indication of a host connection. In a remote application using a Raspberry Pi to control a number of these devices it is desirable to enable the raspberry controller to shut down the USB Vdd and allow the devices to go into sleep mode. Is there a way without rewiring the board to programmatically turn on/off the USB subsystem or just its Vdd?

[blackshard83]

You try to do some testing with hub-ctrl you can find somewhere here in the forums.
Some time ago I tried it but I felt it was not really cutting power to the USB ports. I needed to really cut power to reset some stubborn USB sticks, but was not able to. It also works "reliably" only on rpi2 and upper, but maybe someone which knows the circuitry of the boards can be more helpful.