Pixhawk Cube Orange and Terabee collison avoidance system

We are looking at carrying out a confined space internal inspection of a vertical shaft. We have therefore opted to build ourselves our own custom copter that will be capable to carry out the required objective. The copter platform will consist of using the Pixhawk Cube Orange FC along with the Terabee Tower collision avoidance system. Ideally this combination and correctly setup will help the copter ascend and descend the shaft with the avoidance system aiding the pilot that will be flying predominately First Person View.

The shaft to be inspected has a diameter of 3 meters and spans approximately 90 meters vertically. The Terabee collision avoidance system is mounted centrally on top of the copter meaning that to have the copter positioned within the centre of the shaft, would result in there being 1.5 meters either side from the centre of the Tower sensor array to the shaft walls. I assume with this in mind, the AVOID_DIST_MAX would want to be set to around 1 meter and certainly less than 1.5 meters? If not, surely the collision avoidance system would be continuously correcting itself. What we dont want is for the collision avoidance system to correct and then become locked in a continuous or progressively worsening oscillation.

I have made it so the avoidance system can be turned on and off in flight in the event of the pilot needing to override the sensors.

Having flown the copter outside with AVOID_DIST_MAX = 5 and working successfully, we now start to bring the tolerances down to that of what will be required for the inspection and flying in confined spaces. The copter has no GPS module and therefore operates in flight mode ALTHOLD when the avoidance system is active. When flying without GPS, it would appear that there are only 3 parameters that you can change that will affect the avoidance system: AVOID_ACCEL_MAX, AVOID_ANGLE_MAX & AVOID_DIST_MAX?

Is there any further parameters that’s possible to change that could alter the behaviour of the copter and help it perform better? Or has anyone else achieved this from a different approach? Just a heads up that I have no previous experience with Ardupilot and all of this I’m learning along the way. Any feedback and advice will be greatly appreciated!