FlyQuietly
1 µW
- Joined
- Jul 7, 2016
- Messages
- 3
Hello All,
I have been lurking around RC and robotics forums for awhile and am finally thinking I need to post a few questions if I am going to be successful in a little project I have had on the go for some time now. This isn't exactly e-bike related so I hope users of this form don't mind me posting here. However, I was directed here by a frequent contributor on RC Groups as a board which may have some of the expertise I am looking for.
I have a yardbot (or more strictly speaking yardrov I guess) project in progress on and off for some time now. Since the video below was captured, I have added and articulating implement arm on the front of the rover controlled by a wheelchair linear actuator. My next step is to attempt some sort of cutting attachment on the front of the machine. As you can see in the video, I am a wheelchair user and am unable to push a lawnmower and transfer onto a riding mower is even somewhat beyond my ability.
https://www.youtube.com/watch?v=Oz_a9K1foLA
I have previously considered a "cutting bar" type mower but have been unable to locate a suitable bar which is light enough for my purposes and center driven (considered pilfering one off a hedge trimmer). Also considered towing a gas driven lawnmower, but this seems not a very elegant solution.
My current thinking is a cutting bar with two or three string trimmer heads powered by electric motors. The reason for up to three trimmer heads is to keep center of gravity close to the machine while still achieving a cutting width at least as wide as the machine wheelbase (24"). This would also allow use of reasonably short string trimmer line or rigid cutting blades.
I was anticipating using large outrunner (for the torque) motors capable of running at 24 volts and controlled by matching ESC controllers. Figuring I need something 300 to 500kv or so to allow RPM around 6000 to 10,000 and north of 1 Kw total power as some of the gas trimmers I have seen seem to come in around 1 horsepower. Likely will use a separate receiver (from the one which controls the ROV) mounted on the implement and bound alone to the AUX channel on my 5ch. Spektrum transmitter. Would power the receiver using a 4.8v li/po battery pack with a switch for on/off. This would allow mounting of the implement without having to plug in more than the main power cable. I am willing to spend a bit on motors controllers etc. Consider the cost against purchase of a decent ride-on mower and I have a bit of budget (but still want to keep things reasonable of course).
For motors, I was anticipating using something along the lines of HobbyKing RotoMax 50cc or even 80cc (nothing like overkill) units with ESC's capable of amperage somewhat higher than that required by the motors. I would use on or more Y connectors to allow tandem (tridem?) operation of the motors from one channel. I am anticipating that I should be able to run pretty big motors for reasonably long durations as I don't really have the amp/hours limitations of others who have modified hand-held trimmers with outrunner motors. I am running things off of two G22NF wheelchair batteries rated at 55 amp hours. Weight is not an issue and the amp hours available to me are pretty far in excess of those who have modified hand-held trimmers run on Li/po batteries.
I have questions I think need to be answered before I can actually start ordering parts:
Stalling:
How do I manage the likelihood of occasional to frequent stalls without frying my ESC's or motors? Because I am remote operating this thing in heavy grass, I am very likely not to even notice one or two motors have gotten tangled and stalled. The reading I have done suggests this is going to be a real problem. However, commercial string trimmers seem capable of stalling frequently without difficulty and I even saw a trimmer at Home Depot advertising a brushless motor. Will the ESC overcurrent or overheat safety circuits manage this or do I need to consider brushed motors instead or go some other way?
Run time:
Are these motors capable of running fairly hard for extended periods, even with ESC's that are large enough to easily supply the amperage?
AUX Channel Operation:
Can I simply hook up my receiver to my ESC's, bind to my AUX channel and have the motors fire up when the switch is activated? This channel indicates switch positions 0-1-2. Will this give me off, low and high speed or off, forward and reverse or something else (nothing?). I could use the rudder channel but want to reserve this for something else (weaponization?), don't require progressive speed control and don't want to have to hold the joystick in wide open position all the time. This is likely something more for the RC crowd to answer, however came up with nothing over on RC Groups. Hoping someone here might have some RC knowledge.
Cooling:
In terms of keeping motors and ESC's cool, do I need to consider fans? I think I saw something saying that helicopter motors have built in fans, but I don't seem to have been able to figure out how to identify these exact motors on the HK or manufacturers websites. This has been kind of answered on RC Groups. Sounds like I will need to set up some sort of cooling system. I'm thinking a sealed shroud equipped with a couple cooling fans and air filters at intake and output as will be operating in dusty environments.
Battery Type:
Everything I have seen previously involves running motors off of Li/po batteries. Using lead acid should not be a problem, should it? An electron is an electron, correct?
Unknown unknowns:
Any other advice to assist me in achieving what I am out to do without creating too much expensive white smoke? Am I even on the right track? Feel free to spec this whole thing out for me. Spend my money.
Thank you in advance for any advice and sorry for the long post.
I have been lurking around RC and robotics forums for awhile and am finally thinking I need to post a few questions if I am going to be successful in a little project I have had on the go for some time now. This isn't exactly e-bike related so I hope users of this form don't mind me posting here. However, I was directed here by a frequent contributor on RC Groups as a board which may have some of the expertise I am looking for.
I have a yardbot (or more strictly speaking yardrov I guess) project in progress on and off for some time now. Since the video below was captured, I have added and articulating implement arm on the front of the rover controlled by a wheelchair linear actuator. My next step is to attempt some sort of cutting attachment on the front of the machine. As you can see in the video, I am a wheelchair user and am unable to push a lawnmower and transfer onto a riding mower is even somewhat beyond my ability.
https://www.youtube.com/watch?v=Oz_a9K1foLA
I have previously considered a "cutting bar" type mower but have been unable to locate a suitable bar which is light enough for my purposes and center driven (considered pilfering one off a hedge trimmer). Also considered towing a gas driven lawnmower, but this seems not a very elegant solution.
My current thinking is a cutting bar with two or three string trimmer heads powered by electric motors. The reason for up to three trimmer heads is to keep center of gravity close to the machine while still achieving a cutting width at least as wide as the machine wheelbase (24"). This would also allow use of reasonably short string trimmer line or rigid cutting blades.
I was anticipating using large outrunner (for the torque) motors capable of running at 24 volts and controlled by matching ESC controllers. Figuring I need something 300 to 500kv or so to allow RPM around 6000 to 10,000 and north of 1 Kw total power as some of the gas trimmers I have seen seem to come in around 1 horsepower. Likely will use a separate receiver (from the one which controls the ROV) mounted on the implement and bound alone to the AUX channel on my 5ch. Spektrum transmitter. Would power the receiver using a 4.8v li/po battery pack with a switch for on/off. This would allow mounting of the implement without having to plug in more than the main power cable. I am willing to spend a bit on motors controllers etc. Consider the cost against purchase of a decent ride-on mower and I have a bit of budget (but still want to keep things reasonable of course).
For motors, I was anticipating using something along the lines of HobbyKing RotoMax 50cc or even 80cc (nothing like overkill) units with ESC's capable of amperage somewhat higher than that required by the motors. I would use on or more Y connectors to allow tandem (tridem?) operation of the motors from one channel. I am anticipating that I should be able to run pretty big motors for reasonably long durations as I don't really have the amp/hours limitations of others who have modified hand-held trimmers with outrunner motors. I am running things off of two G22NF wheelchair batteries rated at 55 amp hours. Weight is not an issue and the amp hours available to me are pretty far in excess of those who have modified hand-held trimmers run on Li/po batteries.
I have questions I think need to be answered before I can actually start ordering parts:
Stalling:
How do I manage the likelihood of occasional to frequent stalls without frying my ESC's or motors? Because I am remote operating this thing in heavy grass, I am very likely not to even notice one or two motors have gotten tangled and stalled. The reading I have done suggests this is going to be a real problem. However, commercial string trimmers seem capable of stalling frequently without difficulty and I even saw a trimmer at Home Depot advertising a brushless motor. Will the ESC overcurrent or overheat safety circuits manage this or do I need to consider brushed motors instead or go some other way?
Run time:
Are these motors capable of running fairly hard for extended periods, even with ESC's that are large enough to easily supply the amperage?
AUX Channel Operation:
Can I simply hook up my receiver to my ESC's, bind to my AUX channel and have the motors fire up when the switch is activated? This channel indicates switch positions 0-1-2. Will this give me off, low and high speed or off, forward and reverse or something else (nothing?). I could use the rudder channel but want to reserve this for something else (weaponization?), don't require progressive speed control and don't want to have to hold the joystick in wide open position all the time. This is likely something more for the RC crowd to answer, however came up with nothing over on RC Groups. Hoping someone here might have some RC knowledge.
Cooling:
In terms of keeping motors and ESC's cool, do I need to consider fans? I think I saw something saying that helicopter motors have built in fans, but I don't seem to have been able to figure out how to identify these exact motors on the HK or manufacturers websites. This has been kind of answered on RC Groups. Sounds like I will need to set up some sort of cooling system. I'm thinking a sealed shroud equipped with a couple cooling fans and air filters at intake and output as will be operating in dusty environments.
Battery Type:
Everything I have seen previously involves running motors off of Li/po batteries. Using lead acid should not be a problem, should it? An electron is an electron, correct?
Unknown unknowns:
Any other advice to assist me in achieving what I am out to do without creating too much expensive white smoke? Am I even on the right track? Feel free to spec this whole thing out for me. Spend my money.
Thank you in advance for any advice and sorry for the long post.
