Before you do anymore drilling on the wheels, are those treads the best you can do. You have a nice, flat, sturdy surface, that you can use glue and metal to attach to. You are not getting enough bite with your current configuration, a paddle or "V" tread works good in loose sand. How about the aftermarket body side molding, it comes in long rolls, and has a automotive grade double sided tape, that and a couple metal fasteners each, countersunk per tire width.
Before you do anymore drilling on the wheels, are those treads the best you can do. You have a nice, flat, sturdy surface, that you can use glue and metal to attach to. You are not getting enough bite with your current configuration, a paddle or "V" tread works good in loose sand. How about the aftermarket body side molding, it comes in long rolls, and has a automotive grade double sided tape, that and a couple metal fasteners each, countersunk per tire width.
If it's exclusively offroad and mainly sand, just pop-rivet on some aluminium angle extrusions and be done with it.
Before you do anymore drilling on the wheels, are those treads the best you can do. You have a nice, flat, sturdy surface, that you can use glue and metal to attach to. You are not getting enough bite with your current configuration, a paddle or "V" tread works good in loose sand. How about the aftermarket body side molding, it comes in long rolls, and has a automotive grade double sided tape, that and a couple metal fasteners each, countersunk per tire width.
I will check out the side molding. The bike rubber isn't the best I can do. Mainly because (as erco mentioned) exclusivity to sand. Most of my testing is on a paved driveway, or grass. Once the AWD is working, then it's back to tire modding. It wasn't going anywhere at all without the bike tire.
Erco, I was thinking along the same lines, I would need to curve the metal to match the tire, or put smaller sections of metal bracket on. I could also put the bolt all the way through to the opposite side. Then inject the tire with expanding foam.
Despite a lot of cool solutions that could be used, part of me still thinks the AWD will make it so much better nothing else is needed. The sand in the desert is flat and hard. That beach test was the worst case scenario, and I got stuck, but more importantly I was able to get unstuck : ) All of that was with the weight on the front, and rear wheel drive. I would imagine there will be a vast improvement by shifting the weight and adding power to the front wheels.
Speaking of weight, since it will be AWD, can I leave the batteries where they are? It's such a nice spot compared to anything further aft.
Before you do anymore drilling on the wheels, are those treads the best you can do. You have a nice, flat, sturdy surface, that you can use glue and metal to attach to. You are not getting enough bite with your current configuration, a paddle or "V" tread works good in loose sand. How about the aftermarket body side molding, it comes in long rolls, and has a automotive grade double sided tape, that and a couple metal fasteners each, countersunk per tire width.
I will check out the side molding. The bike rubber isn't the best I can do. Mainly because (as erco mentioned) exclusivity to sand. Most of my testing is on a paved driveway, or grass. Once the AWD is working, then it's back to tire modding. It wasn't going anywhere at all without the bike tire.
Erco, I was thinking along the same lines, I would need to curve the metal to match the tire, or put smaller sections of metal bracket on. I could also put the bolt all the way through to the opposite side. Then inject the tire with expanding foam.
Despite a lot of cool solutions that could be used, part of me still thinks the AWD will make it so much better nothing else is needed. The sand in the desert is flat and hard. That beach test was the worst case scenario, and I got stuck, but more importantly I was able to get unstuck : ) All of that was with the weight on the front, and rear wheel drive. I would imagine there will be a vast improvement by shifting the weight and adding power to the front wheels.
Speaking of weight, since it will be AWD, can I leave the batteries where they are? It's such a nice spot compared to anything further aft.
With awd a 50/50 weight distribution is good. If it is close to that now you may as well leave the batteries where they are.
The axle in the first pic (taken from the front) needs to be about right there to match the rear. There's a vertical gap larger than the pillow blocks.
In the second pic (taken from the rear) you can see a flat area above the axle. I could cover that with thick sheet metal that extends down far enough to attach the pillow blocks. It would make the front wheels about an inch further forward than they should be.
I guess that means whatever sheet metal is used will need a 90 degree bend in it. That way I can control the placement in both directions and get the wheel centered. Luckily there's a metal shop nearby that will do stuff like that while you wait. Or, I could attach angle bracket to the sheet metal and get similar results. I have a week to figure that out.
Batteries: The battery placement is going to be harder than I thought. Putting them on the seats moves the weight 80% rear. The only way to get them in the center would be to cut giant holes in the bottom, or mount them to the bottom. Cutting the holes would require adding additional reinforcements. Mounting them to the bottom wouldn't reduce ground clearance, but there's no good flat spots to do it.
Camera: Third pic. I got this camera https://www.amazon.com/SecuPlug-100-150ft-1920x1080-Resolution-Supported/dp/B01DT3RMJQ for $150 on eBay open box. I installed it on the outside of my condo, it's hidden so it doesn't have much of a view. The camera is awesome. It needs paint, it will match the rover color. I will test out the night vision tonight. It has a large image sensor and 6 big IR LEDs. The best part is the 360 degree rotation, now the rover's "head" doesn't have to move. That reduces the time and complexity, which means less crying if the rover disappears.
The camera is great, it has 4 IR LEDs, the bottom two lenses cover a laser for the auto-focus. The night vision and image quality are better than any cheap PTZ camera I've used. If you need an outdoor PTZ camera this is a really good deal in comparison to anything in its price range. Unless of course it stops working in a few months.
About the skid steering. When I think of skid steering, the first thing that comes to mind is the robot rotating in place about the Z axis. That to me seems like it would be very hard for the rover to do. The thing is, it probably doesn't matter. So long as I can match the turning radius of the old steering, who cares about rotating in place? Not this guy, skid steering all the way.
I made a mockup of the pillow block so I can get the metal bracket made before Friday. I also had to order another motor controller. I will hopefully be posting a video this weekend!
Each motors controller has two independent channels. They could be used as a single channel with twice the output. That's probably what I'd do, and use one per side.
I haven't been able to do anything because my garage became a storage unit for someone. At some point, I will put the stuff out on the street and resume working on the rover.
I haven't been able to do anything because my garage became a storage unit for someone. At some point, I will put the stuff out on the street and resume working on the rover.
Throw the bum's out, unless they are paying for storage.
The sheer audacity of the whole thing, to intrude on your private little skunk works. This kind of thing keeps pushing back the deployment date. And increases the overall budget. Not to mention fraying the nerves of the design team. Who can't do the needed testing, so his investors will get off his back.
Sounds like a vicious circle, you need to change something xanadu!
Thanks Mike. It can't possibly go on much longer. I think we should be good after the 15th which is only a few days away.
In the meantime, I've been backpedaling on the Power Wheels chassis. I have these four sweet pillow blocks. I could use the wheels and motors, axles, and these blocks on any chassis. A DIY chassis could square up the wheelbase, and allow for better battery weight distribution. I would have to check some scrap metal places for something that could be used as a chassis. It would also have to be inexpensive or free. Then, I'd probably want four wheel steering, and this project would never end. The second rover could be the good one, we can't go leaving the good one out in the desert haha.
Instead I built the essentials bus controller. It's a Prop Protoboard with an MCP3208 ADC connected to battery terminals and current shunts. Another 8 pins going to the octo-relay board. The ADC uses 4 pins, for a total of 12 pins, and just 1 cog. It spends most of the day sleeping...
I am able to monitor the individual voltages of the batteries, overall current and overall voltage. The relays will be handing power to things like the modem, camera, 2nd Prop, sensors, solar panel disconnect, etc. This one will not be field programmable, so I figured it's a high priority to start testing. Also, it's a lot easier than this chassis stuff!
These pillow blocks pushed me close to my limit. They are not 3/4". They're at least 1 mm smaller! I ended up chucking the axle in my drill, sanding and filing for a long time. It was not enough, the middle block got stuck on the axle. It's staying there. I ran out of metal, and ended up mounting the axle an inch or so to the rear. Fenders will need to be trimmed if we go with wheel paddles.
Next, stop the gearbox from moving on the axle. That shouldn't take much. Then solder some caps and wire and hookup the new motor controller. I've already updated my RC code to accommodate the additional motors.
Here are some pics. There are a couple of bolts missing in the 3rd pic, the one from the side. It's nothing like the previous front end, it's very tight and should work great. The rover tracks straight rolling it by hand
Thanks Eric. Now that the drilling and cutting is done I moved it back inside. I used a ziptie to hold the motor in place. It can't move laterally so it doesn't take much, I'll replace it with a U bolt.
The front motors are the original rear motors that I replaced with new stuff. I can't see the brushes because I don't think I could get it back together. Suddenly replacements are hard to find. I'm not sure what to do about that.
I couldn't help but connect all four motors to power. It looks unstoppable
I ran into a code issue. I have narrowed it down to the code by swapping some wires around. The front right motor will not turn until the other motors are around 75% power then it kicks in. Here's a stripped down version, it runs all 4 motors at the same speed. It acts the same as the radio controlled version. I also tried assigning different Prop pins to the weird channel. The object says it will work with 32 independent PWM channels. I'm lost...
{{
Rover Motor Test
}}
CON
_CLKMODE = XTAL1 + PLL16X
_XINFREQ = 5_000_000
OBJ
PWM : "PWM_32_v4.spin" 'used for motor controllers
PUB main
PWM.Start 'initialize PWM cog
waitcnt(clkfreq * 1 + cnt)
'0 rear left pwm pin
dira[1] := 1 ' rear left enable pin
dira[2] := 1 ' rear left enable pin
'3 rear right pwm pin
dira[4] := 1 ' rear right enable pin
dira[5] := 1 ' rear right enable pin
'6 front left pwm pin
dira[7] := 1 ' front left enable pin
dira[8] := 1 ' front left enable pin
'9 front right pwm pin
dira[10] := 1 ' front right enable pin
dira[11] := 1 ' front right enable pin
'go forward slowly
repeat
outa[1] := 0
outa[2] := 1
outa[4] := 0
outa[5] := 1
outa[7] := 0
outa[8] := 1
outa[10] := 0
outa[11] := 1
PWM.Duty(0,20,2000)
PWM.Duty(3,20,2000)
PWM.Duty(6,20,2000)
PWM.Duty(9,20,2000)
waitcnt(clkfreq * 1 + cnt)
Nevermind. It's working now. I don't really understand why wasn't, but the important thing is I can finally drive it. After adding in the steering part.
You don't need full encoders but some way to verify that all motors are working would be a good idea. If one motor failed and all the others just kept going they would quit one by one. Assuming its moving autonomously that is.
Comments
Mounted shoulder bearings?
The lazy susan bearing is perfect for keeping the steering intact. The shoulder bearings are good for the skid steering.
If it's exclusively offroad and mainly sand, just pop-rivet on some aluminium angle extrusions and be done with it.
I will check out the side molding. The bike rubber isn't the best I can do. Mainly because (as erco mentioned) exclusivity to sand. Most of my testing is on a paved driveway, or grass. Once the AWD is working, then it's back to tire modding. It wasn't going anywhere at all without the bike tire.
Erco, I was thinking along the same lines, I would need to curve the metal to match the tire, or put smaller sections of metal bracket on. I could also put the bolt all the way through to the opposite side. Then inject the tire with expanding foam.
Despite a lot of cool solutions that could be used, part of me still thinks the AWD will make it so much better nothing else is needed. The sand in the desert is flat and hard. That beach test was the worst case scenario, and I got stuck, but more importantly I was able to get unstuck : ) All of that was with the weight on the front, and rear wheel drive. I would imagine there will be a vast improvement by shifting the weight and adding power to the front wheels.
Speaking of weight, since it will be AWD, can I leave the batteries where they are? It's such a nice spot compared to anything further aft.
With awd a 50/50 weight distribution is good. If it is close to that now you may as well leave the batteries where they are.
Well, since you asked so politely, OK.
But just this once.
Tonight's the night, I figure a trip to Lowe's and some luck and we'll have AWD.
The axle in the first pic (taken from the front) needs to be about right there to match the rear. There's a vertical gap larger than the pillow blocks.
In the second pic (taken from the rear) you can see a flat area above the axle. I could cover that with thick sheet metal that extends down far enough to attach the pillow blocks. It would make the front wheels about an inch further forward than they should be.
I guess that means whatever sheet metal is used will need a 90 degree bend in it. That way I can control the placement in both directions and get the wheel centered. Luckily there's a metal shop nearby that will do stuff like that while you wait. Or, I could attach angle bracket to the sheet metal and get similar results. I have a week to figure that out.
Batteries: The battery placement is going to be harder than I thought. Putting them on the seats moves the weight 80% rear. The only way to get them in the center would be to cut giant holes in the bottom, or mount them to the bottom. Cutting the holes would require adding additional reinforcements. Mounting them to the bottom wouldn't reduce ground clearance, but there's no good flat spots to do it.
Camera: Third pic. I got this camera https://www.amazon.com/SecuPlug-100-150ft-1920x1080-Resolution-Supported/dp/B01DT3RMJQ for $150 on eBay open box. I installed it on the outside of my condo, it's hidden so it doesn't have much of a view. The camera is awesome. It needs paint, it will match the rover color. I will test out the night vision tonight. It has a large image sensor and 6 big IR LEDs. The best part is the 360 degree rotation, now the rover's "head" doesn't have to move. That reduces the time and complexity, which means less crying if the rover disappears.
About the skid steering. When I think of skid steering, the first thing that comes to mind is the robot rotating in place about the Z axis. That to me seems like it would be very hard for the rover to do. The thing is, it probably doesn't matter. So long as I can match the turning radius of the old steering, who cares about rotating in place? Not this guy, skid steering all the way.
I made a mockup of the pillow block so I can get the metal bracket made before Friday. I also had to order another motor controller. I will hopefully be posting a video this weekend!
What has two thumbs, speaks French, and thinks your skid steering is da bomb?
MOI! (translates to "this guy")
Thanks, eventually I start to catch on : )
Now that I have 4 motors, and 2 motor controllers... Should I use one motor controller for the front wheels, and one for the back?
Or, should I use one for each side?
The more I think about it, the further away from a conclusion I get...
Your left wheels always rotate together in the same direction.
Your right wheels always rotate together in the same direction.
Or did I miss something...?
For some reason I would say one for front and one for back. Two wheels may get you somewhere.
Jim
I haven't been able to do anything because my garage became a storage unit for someone. At some point, I will put the stuff out on the street and resume working on the rover.
Throw the bum's out, unless they are paying for storage.
The sheer audacity of the whole thing, to intrude on your private little skunk works. This kind of thing keeps pushing back the deployment date. And increases the overall budget. Not to mention fraying the nerves of the design team. Who can't do the needed testing, so his investors will get off his back.
Sounds like a vicious circle, you need to change something xanadu!
In the meantime, I've been backpedaling on the Power Wheels chassis. I have these four sweet pillow blocks. I could use the wheels and motors, axles, and these blocks on any chassis. A DIY chassis could square up the wheelbase, and allow for better battery weight distribution. I would have to check some scrap metal places for something that could be used as a chassis. It would also have to be inexpensive or free. Then, I'd probably want four wheel steering, and this project would never end. The second rover could be the good one, we can't go leaving the good one out in the desert haha.
Check these out -
Jim
Instead I built the essentials bus controller. It's a Prop Protoboard with an MCP3208 ADC connected to battery terminals and current shunts. Another 8 pins going to the octo-relay board. The ADC uses 4 pins, for a total of 12 pins, and just 1 cog. It spends most of the day sleeping...
I am able to monitor the individual voltages of the batteries, overall current and overall voltage. The relays will be handing power to things like the modem, camera, 2nd Prop, sensors, solar panel disconnect, etc. This one will not be field programmable, so I figured it's a high priority to start testing. Also, it's a lot easier than this chassis stuff!
Could help to put more toys in the toy box.
Next, stop the gearbox from moving on the axle. That shouldn't take much. Then solder some caps and wire and hookup the new motor controller. I've already updated my RC code to accommodate the additional motors.
Here are some pics. There are a couple of bolts missing in the 3rd pic, the one from the side. It's nothing like the previous front end, it's very tight and should work great. The rover tracks straight rolling it by hand
The front motors are the original rear motors that I replaced with new stuff. I can't see the brushes because I don't think I could get it back together. Suddenly replacements are hard to find. I'm not sure what to do about that.
I couldn't help but connect all four motors to power. It looks unstoppable
{{ Rover Motor Test }} CON _CLKMODE = XTAL1 + PLL16X _XINFREQ = 5_000_000 OBJ PWM : "PWM_32_v4.spin" 'used for motor controllers PUB main PWM.Start 'initialize PWM cog waitcnt(clkfreq * 1 + cnt) '0 rear left pwm pin dira[1] := 1 ' rear left enable pin dira[2] := 1 ' rear left enable pin '3 rear right pwm pin dira[4] := 1 ' rear right enable pin dira[5] := 1 ' rear right enable pin '6 front left pwm pin dira[7] := 1 ' front left enable pin dira[8] := 1 ' front left enable pin '9 front right pwm pin dira[10] := 1 ' front right enable pin dira[11] := 1 ' front right enable pin 'go forward slowly repeat outa[1] := 0 outa[2] := 1 outa[4] := 0 outa[5] := 1 outa[7] := 0 outa[8] := 1 outa[10] := 0 outa[11] := 1 PWM.Duty(0,20,2000) PWM.Duty(3,20,2000) PWM.Duty(6,20,2000) PWM.Duty(9,20,2000) waitcnt(clkfreq * 1 + cnt)PWM Object - http://obex.parallax.com/search/pwm_32