Showroom 6DOF 48V Brushless DC Project

So after much research here is my 6DOF Simulator.

A massive thank you to pmvcda (FlyPT) for his amazing work on which this project is largely based. Also thanks to SilentChill for much inspiration and Hoddem, SeatTime, wannabeaflyer2 for actuator design ideas. Gabor Pittner for an improved control board design. Finally to My.stAr for great 6DOF explanations and noorbeast & the Xsimulator staff for this amazing platform.

The primary aims for this simulator:
- 6DOF with decent angles and rapid motion >300mm/sec
- Compact as possible whilst retaining the recessed hexapod low centre of gravity design and a 1.5m dia floor working area
- Quiet smooth motion
- Lightweight (Aluminium + Composite seat) and easy to move/disassemble
- Relatively low budget <£2000 inc seat but + accessories



I assessed 4 Motor options and 2 actuator designs
- Ampflow e30-150 24V DC Brushed + Sabertooth 2X60 with pot feedback
- 57BLF03 24V BLDC Motor + 8015A Controller using FlyPTs Hall feedback
- 86BLF03 48V BLDC Motor + 8015A Controller using FlyPTs Hall feedback
- 6374 Outrunner BLDC Motor + Odrive and AMT encoder feedback

Through testing the Ampflow has excellent RPM (5000rpm) and good noise levels (67db on bench - max rpm - no load) but the potentiometer feedback required more complexity and Sabertooth were controllers more expensive. The outrunner BLDC motor was noisy (86db) when tested with available controller (Vesc) and Odrives + encoders are an expensive option. Power levels were good and many winding/rpm options are availible.

The Final two motors 57BLF03 and 86BLF03 are in convenient NEMA sizes and though not as powerful as the BLDC option or (in the case of 57BLF03) as much torque as the Ampflow they are cheap, easily available and really quiet (51 and 58db respectively). 86BLF03 was selected in the end as it provided more torque (larger diameter) and at 48V reduced the current. Both motors run 3500rpm no load on the bench despite 3000rpm ratings.

I have opted for a belt drive (inverted motor) as the actuator is more compact and gearing can be changed. SFU1610 (10mm pitch) ballscrews provide faster motion at lower rpm reducing noise at the expense of more load on the motor.

Initially had intended on an open frame actuator design with some 3d printed parts but despite ease of manufacture this proved quite noisy - partly due to resonance from the extruded box section at its base. However provided useful information for the final enclosed actuator design.


More to follow...

So the sim is up and running and is a lot of fun. I am yet to fit the screen as need to reinforce the top rig mounts to support the weight. The final design uses the 86BLF03 with the hall sensors replaced with AMT102 encoders and runs 3 odrives. Despite initial difficulties setting up the odrives to run well (they currently have a 48V lithium battery in series for high current pulses) they have been reliable and save an enormous amount of wiring limit switches, separate motor controllers etc. When the cost of producing customised PCBs for the original FlyPT ESP32 control board design and extra wiring is taken into account the Odrives work out slightly cheaper too as well as supporting a wider variety of motors and having better smoothing/cogging reduction.

Reserved...

Interesting.....SFU1610 ballscrew ........I follow your thread to see the result... I like the design of your linear actuator...Can you give more details about your actuator ? (Drawing)

I am very interested in your project. Do you already have more information about the actuators? And do you already have your build working?

Regards,
Builder

So I went for the 10mm pitch as opposed to the more common SFU1605 because it gave me faster actuation at lower input rpm and theoretically less noise. In hindsight as the motors (86BLF03) i'm using have a fairly low pole count the actuation is a bit jerkier (lower finite resolution) and less smooth than might be perfectly ideal. Fine for racing but a little more resolution might be good for flight sims. However motion is fast, theoretically at 3000rpm rated the actuators peak at a rapid 500mm/s. I've found these super rapid movements are nice for small vibrations but can result in a pretty exciting crash if the profiles are not well tuned and you hit something.

Long story short, go for 5mm ballscrews, they're plenty fast enough and cheaper/easier to find. I am investigating leadscrews for silent running with slightly less efficiency - though i'm barely pushing my motors as it is so should have the capacity. Will report on that soon.

The actuators contain a few CNC parts as I have access to a machine. The design inverts the motor and adds a T5 (10mm wide pulley) belt drive to the base of the actuator to shorten the overall length and make the sim more compact. In hindsight I would have gone for a more compact motor in direct drive format as it reduces the complexity and cost. The base plate attaches to a standard style Universal joint (https://www.ebay.co.uk/itm/12mm-Dia...633876?hash=item2178349994:g:wG8AAOSwB95fbAaO)

Above the UJ base plate there are three turned standoffs which connect to the main motor mount. A FK10 bearing is attached to this plate as well as a coupler for the actuator tube and two 8mm stainless steel rod guide rails.

The ballscrew bearing is mounted to a 3D printed part (90%infill PLA) which has two IGUS (GSM-0810-36)linear polymer bushings pressed into it (to run on the 8mm rails).

Top mount is connected to the 8mm guide rails and the outer casing and contains 1x IGUS GFM-2528-16 bushing pressed in. This runs on the 25mm aluminium actuator shaft up to the top universal joint.

The ballscrews are 450mm long and allow an actuation throw of around 310mm.

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