Denny Rowland's Posts (6)

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VCA from Denny Rowland on Vimeo.

I know from some contacts in the business that there are going to be some significant improvements in the supply of more suitable brushless gimbal motors. however I have always been of the opinion that a full movement 3 axis gimbal was quite a silly idea when the model itself provides us with a very good 3 axis of stabilized movement that needs only to be corrected for a small degree of unwanted movement. High end mil. spec. stuff works on the principle of having an inner (high sensitivity) and an outer axis that works independently to form a much higher degree of accuracy than we will ever see from the brushless system that we currently use. This inner axis is normally created around the use of voice coil actuators. They are far more efficient, faster, powerful and have a linear output. The name comes from the speaker coil that is used to vibrate a paper coil to create sound waves. It can also attenuate the kind of vibration that we see on a typical MR craft. There are however several different types.

So here's one in action on a development platform for a well known Vision MR that desperately needs it.

This prototype Rotary VCA came from the magnets out of a Hard drive and the coil was hand made to test the principle of controlling a single phase actuator with a standard brushless gimbal controller using just two adjacent output pins.

Shown here with a 7.4v. power supply but it has now moved on to 14.8v  It is controlling the yaw function with Follow mode which means that it returns to to models heading after correcting for a disturbance. The yaw movement is not shown as it is  going into production but I can tell you that it floats the full 95 deg. tilt axis and the camera assy on a magnetic field. 


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ROWLAND F1-535 nears production status

So guys here is what a finished one looks like. The level of stabilization is unbelievable, a key factor is in the torsional rigidity of the motor arms and the weight of the props. Whatever you do electronically I think it will be impossible to replicate this with upright long motors on a long stick. Demo videos will start when the weather improves. Bur after weeks of non stop wind and rain, efforts have been shifted to further dev. work.   


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Aerodynamic efficiency

As everybody is working on ways to improve electronic response I thought it was time I did a little work to see what can be done beyond the electric motor.  Coanda and Bernoullis effect put to good use.3689416485?profile=original
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New aerial video platform

3689405638?profile=originalThis is the latest Flying Multicopter Camera system. It uses the Panasonic HDC-TM900. The arms are on rubber mounts and only move if there is any vibration. The motors are Pulso X2826/12 Kv 760 they have 5mm shafts and are three bearing. They run very smoothly compared to the MK3538's. Three axis of inner stabilisation on the camera mount plus three outer on the model itself. It is made from balsa, plywood and insulation foam covered with epoxy resin and lightweight cloth. Strong, light and it floats. Rock steady imagery, even when zoomed to 80X. Still waiting to get the latest code for the FC. The only bit that I really need help with.
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Having got to the point where I have engineered a multi-rotor flying camera mount that works to a very high level of stabilization (sub .05 deg.) I need to complete the puzzle with some help in designing some boards to compliment the APM system. Then the community at large can buy off the shelf, here at DIYDrones, the right components to do the job properly.

I am not an EE so I probably don't know what I am talking about but I do know the aerial camera mount business inside out. As I see it, the task is this. Camera mounts need to have a very different approach to that of stabilizing a multi-rotor copter. It is a lot simpler for a start. 300/500 deg/sec gyros typically output 2mv./ deg/sec but Invensense for example make gyros specifically for the job of stabilizing camera IS lenses and camera platforms the IDG 1150 for example is a 20 deg/sec. gyro that can output 50 mv/deg/sec. other gyros are available that have dual output that amplify the signal by a factor of 4, but as I see it this only amplifies the critical area which is at the very initial point of movement - noise. Sub .00? is normally only achievable with mil. spec. fiber optic gyros which are way beyond affordability in our case, but as Mems systems have come along in leaps and bounds recently. I believe we can do this to create top professional results at very little cost. Such high sensitivity modules would only work in a vibration free environment and this problem has been addressed and a complete solution is now available. Along the way a multi-rotor craft has been developed that not only is aerodynamically better than conventional designs but it uses materials that float on water and give better crash resistance and weight. Such a craft can be made using cheap materials that are freely available and can be fabricated with simple tools.

The 5/6 axis system explained. We all know that it is only possible to move a camera thro 3 axis of movement - pan, tilt and roll. the typical high end gyroball device uses the inner axis principle to fine tune the high accuracy movements.

Our model can create that outer axis and with a just little more work can be made to integrate perfectly with an inner axis system. The inner axis can be a simple 2 axis module device or a more complex 3 axis. The 2 axis module would be attached to the camera base plate and would have pwm in /out and utilize 2 axis acc. to reference gravity. The 3rd axis again a stand alone module would be in the Z axis (Pan) and integrate with the FC's mag.

Once this has been achieved we can step into the really exiting stage which is to create a total system where the operator simply fly's the camera and the copter follows the camera's desired track. it will use optic flow technology to look at the cameras LCD and augment stabilization and create an auto object tracker. WOW.


My prototypes are made using components such as heading lock gyros that have been modified to accept high sensitivity gyros but these are created as simple test bed components and need a lot of sorting out  before they could be used commercially.

I have only just started with APM so do excuse my ignorance if I made false assumptions at any time.

Most of my model development was done with a simple KK FC so as to create a reliable benchmark. I later moved onto the MK system which did not cut the mustard. It became known as the MK fireworks kit as ESC's and power distribution boards would burst into flames for no apparent reason and then there was the death roll gyro problem where hundreds of duff FC boards were sold to the unsuspecting masses. It would try to transit cumula granite resulting in the spectacular drop kick bang smash. They were the days! Onwards and upwards as they say. Interested anybody?

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Hi Guys I have for some time been developing this flying camera, I say camera as this is a departure from the norm. Whereas most people make a copter that just happens to have a camera mount this is different. The operator fly's the camera and the uav follows the envelope that is required to stay within the shooting angles selected. I am new to arduino so any help is what I need most. It has a number of other features such as the ability to land on water.

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