Post by dependable on Nov 5, 2013 11:15:51 GMT
Here's a thread I had posted on the Freefly Forums but John Cunningham solved the problem and I thought it was one worth sharing...
Hi All,
I have a problem balancing our 3 axis photohigher AV200. The camera is as physically well balanced as I can get it. The roll and pan Radians seem to be performing as expected. The tilt Radian/servo is a different matter.
Whenever it's initialised, it makes a sudden pan down. If the gain is set high (80% or above) and I physically hold the camera on initialisation it starts working but oscillates terribly. So I reduce the gain to get to the sweet spot which seems to be around 25-30%. However, if I switch the gimbal off and on again, it does the "usual" tilt down followed by a very dramatic tilt down to beyond the end stop causing the gearing in the servo to make horrible noises! The only solution is to switch it off in a hurry!
Here's the detail including video of the problem. In response to those who suggest changing to Freefly servos, would one servo v another really cause such an extreme problem. I can appreciate some may be better than others but I have two working fine and one doing very strange things - not just not great if that makes sense?
Aircraft Type: Skyjib X4
Gimbal Type: Photohigher AV200
Radian Type ( 1, 2 , 3 axis) 3 axis
Gimbal Power source: 4S 2600mah
Gimbal Radio Type: DX8i
Radian Communication Protocol (S.Bus, PPM, PWM, Spektrum) Spektrum
Connections: Change these to match your setup
Roll Sensor:
Port
1. Power from AR8000
2.
3. To Tilt sensor
4. To Roll Servo
Also input from Spektrum Satellite
Tilt Sensor:
Port
1.From Roll Sensor
2.
3.To Pan Sensor
4.To Tilt servo
Pan Sensor:
Port
1.From Tilt sensor
2.
3.
4.To pan servo
Symptoms: See video for full explanation
Steps taken to resolve:Wiring checked. Settings checked. Advice sought!
Problem is shown in this video:
play.webvideocore.net/poppla...on=#FFFFFF&colorHighlight=#fcad37&direct=true
Radian Setting are shown in this video:
play.webvideocore.net/poppla...on=#FFFFFF&colorHighlight=#fcad37&direct=true
Following a few responses on the FF forum I completely re-wired the Radians to go Pan, Roll Tilt and this just introduced the problem on Roll as well! At that point the entire system nearly went on Ebay!
Long story short...
Following a lot of hard work, frustration and invaluable assistance over the weekend the problem is sorted (or at least it will be once I've got another potentiometer) I hope the solution will help others to better understand how these things work. The issue was the resistors that had been fitted to our gimbal where incorrect. I now understand that the 'Servo Out' indicator in the Radian Software needs to be at zero. Ours were both at +55% (Tilt and Roll) but pan was at 0. I had no idea either what that meant or that this would cause a problem. Apparently, that figure shows how much work the servo is having to do to hold the axis steady. If it's too far off centre, it effectively runs out of travel and can't work properly. I think that we may have got away with it with a lighter camera. That's my lay person's understanding of the problem.
The solution was to borrow a potentiometer out of a servo, attach this to the servo and tune the 'servo out' to get it to zero i.e. the servo is effectively in it's centre position when the system is level. Having done that, the tilt now initialises without a single twitch and is so much smoother than it has been! We just need a second pot to do the same to the roll and I think we'll be there.
I can't find any reference to this stuff in any manual or am I wrong? Maybe the FF servos and resistors come pre-matched but given that they are sold as seperate units, it might be helpful to make clear what the resistors are actually doing and what you need to try to achieve with them.
All credit for this solution has to go to John Cunningham who has been kind enough to respond to all my emails this weekend and spent an hour on Skype with me yesterday to diagnose the problem and suggest this solution but I thought it hugely important the solution is shared on here. He's been a real star
Hi All,
I have a problem balancing our 3 axis photohigher AV200. The camera is as physically well balanced as I can get it. The roll and pan Radians seem to be performing as expected. The tilt Radian/servo is a different matter.
Whenever it's initialised, it makes a sudden pan down. If the gain is set high (80% or above) and I physically hold the camera on initialisation it starts working but oscillates terribly. So I reduce the gain to get to the sweet spot which seems to be around 25-30%. However, if I switch the gimbal off and on again, it does the "usual" tilt down followed by a very dramatic tilt down to beyond the end stop causing the gearing in the servo to make horrible noises! The only solution is to switch it off in a hurry!
Here's the detail including video of the problem. In response to those who suggest changing to Freefly servos, would one servo v another really cause such an extreme problem. I can appreciate some may be better than others but I have two working fine and one doing very strange things - not just not great if that makes sense?
Aircraft Type: Skyjib X4
Gimbal Type: Photohigher AV200
Radian Type ( 1, 2 , 3 axis) 3 axis
Gimbal Power source: 4S 2600mah
Gimbal Radio Type: DX8i
Radian Communication Protocol (S.Bus, PPM, PWM, Spektrum) Spektrum
Connections: Change these to match your setup
Roll Sensor:
Port
1. Power from AR8000
2.
3. To Tilt sensor
4. To Roll Servo
Also input from Spektrum Satellite
Tilt Sensor:
Port
1.From Roll Sensor
2.
3.To Pan Sensor
4.To Tilt servo
Pan Sensor:
Port
1.From Tilt sensor
2.
3.
4.To pan servo
Symptoms: See video for full explanation
Steps taken to resolve:Wiring checked. Settings checked. Advice sought!
Problem is shown in this video:
play.webvideocore.net/poppla...on=#FFFFFF&colorHighlight=#fcad37&direct=true
Radian Setting are shown in this video:
play.webvideocore.net/poppla...on=#FFFFFF&colorHighlight=#fcad37&direct=true
Following a few responses on the FF forum I completely re-wired the Radians to go Pan, Roll Tilt and this just introduced the problem on Roll as well! At that point the entire system nearly went on Ebay!
Long story short...
Following a lot of hard work, frustration and invaluable assistance over the weekend the problem is sorted (or at least it will be once I've got another potentiometer) I hope the solution will help others to better understand how these things work. The issue was the resistors that had been fitted to our gimbal where incorrect. I now understand that the 'Servo Out' indicator in the Radian Software needs to be at zero. Ours were both at +55% (Tilt and Roll) but pan was at 0. I had no idea either what that meant or that this would cause a problem. Apparently, that figure shows how much work the servo is having to do to hold the axis steady. If it's too far off centre, it effectively runs out of travel and can't work properly. I think that we may have got away with it with a lighter camera. That's my lay person's understanding of the problem.
The solution was to borrow a potentiometer out of a servo, attach this to the servo and tune the 'servo out' to get it to zero i.e. the servo is effectively in it's centre position when the system is level. Having done that, the tilt now initialises without a single twitch and is so much smoother than it has been! We just need a second pot to do the same to the roll and I think we'll be there.
I can't find any reference to this stuff in any manual or am I wrong? Maybe the FF servos and resistors come pre-matched but given that they are sold as seperate units, it might be helpful to make clear what the resistors are actually doing and what you need to try to achieve with them.
All credit for this solution has to go to John Cunningham who has been kind enough to respond to all my emails this weekend and spent an hour on Skype with me yesterday to diagnose the problem and suggest this solution but I thought it hugely important the solution is shared on here. He's been a real star