04.12.17 Independent Study, Journal 10
04.12.17 Talked to Gene
I tried to talk to Gene about the battery. He explained what happened. He said I probably did not have enough current going to the motors and burned out the motors and damaged the battery. He couldn’t tell me what to do about it. He said he needed more info. I am stressed because Ill never be ready to present if I don’t get it rebuilt. I made a tight schedule to try and get things done. I sent Gene and E-mail about the motors
Email to Gene:
my rechargeable battery is definitely an issue. It does not seem to be delivering consistent power. It is supposed to be 12 volts but I am only measuring 6. I thought maybe it was just out old juice but it charged all night. I don’t really understand how it is possible. I understand that batteries get old, but I did not think they lost voltage.
One way or another, my motors are dead. I read up and it sounds like they were allowed to try and spin for too long. They did not spin and therefore did not cool themselves and therefore died. At least that’s what most of my research suggestions. To be honest, I am kind of confused by that too. I never let them sit with power through them for all that long. It seems like they should be more durable than that.
I ordered new motors. They will be here tomorrow.
I was pretty upset since this happened after I thought it was all fixed. I had my new acrylic platform up and running. It was messy and held together with zip-ties and wires, but it was running. I transferred everything to the wooden robot and then the motors died.
I have about a week and a half to be prepared to show this robot at the symposium. You know I did not want to show the robot while it was in progress, but I agreed to it as per the terms of the grant. Now I am really worried because even if I can fix the current problems, that does not leave me much time to work out the code. Right now I am still modifying someone else’s code. I am getting better but Im not quite there yet.
I am thinking about setting the project up at the Symposium up as some kind of design project that highlights how the robot will be stack-able and used for prototyping. I think that at this point, that is the most interesting thing. I think the design aspect actually has a lot of potential in the future. There is a lot of writing I want to do (and have been doing) about this process.
I could get the robot body rebuilt and make some kind of single page info graphic showing how it comes apart and explaining it’s use for prototyping. If you think it is appropriate, I could add a bullet list of project goals to show where it is going after the prototyping design is perfected. Hopefully, if I show it with my studio project, it will make a reasonably good presentation. Do you think that will be acceptable for the Symposium?
Hopefully, I will have the code worked out by the end of the semester. I found someone else’s code that helped me a lot because he explained each section of the code and it helped me see how to put the functions together. I think his obstacle avoidance code is good. I need to add a random movement function so that when the robot does not have an obstacle, it does something.
Then I am a step away from object-following. maybe… I ran that on the acrylic robot but I am not sure if it was working or not. It seemed to be but it was so buggy that I cant be sure. I ordered different distance sensors that I understand to be more precise. Hopefully they will be here soon and I can try the code again .If I do, I can run it on the little acrylic robot as well. It will look terrible, but it will let us see how the robot interacts with another robot.
04.13.17 E-mail to Gene
Sorry for sending in multiple E mails. I hate typing on my phone.
I have the new motors. They work fine when connected to a 12 volt power supply.
I sent a picture of the battery, some relays and the voltage regulator I bought.
I selected this battery because I saw 3 options. I could use the expensive RC car 12 Volt batteries that require a special charger. The charger would allow me to pluginto a port so if it were not so expensive I would have used it.
I did salvage a 7.5 Volt RC car battery from a toy but that is not enough for these motors. I am guessing the toy in question had some kind of relay or amplifyer because it seems to also have a 12 volt motor but I did not salvage that.
I also looked at lead acid batteries but they were big and bulky and had even more expensive chargers.
I could have used a grouping of several individual batteries but I would have to remove and replace frequently which I did not want to do.
I saw several batteries like the one that I bought. They varied only in the number of ports and the mAh value. I bought the biggest one I could afford. I figured that if I could play games for 10 hours on my phone with a 10,000 mAh external charger, then I could probably run a robot for at least a couple of hours at a time. I decided to just go with that and save efficiency for the smaller future robots.
Obviously, I made an error, Now I have to solve it. I really need to redo the robot body this weekend. I wont have anything presentable in time for the Expo if I do not I don’t have to have the motors and batteries functioning to do that, but I do need to know if I am going to have to change to a totally different battery size. I did not leave space for very much change. I did as much research as I could today.
I checked the current battery again and it is showing 11.1 Volts. I am not sure of the other battery. It needs to be charged again I think. The problem is, even though the battery says it is a 12 Volt max. It only stays at 12 volts for a very short time. That is not going to allow any functionality. The robot cant die after 20 minutes.
The motor shield says it has: 4 H-Bridges: L293D chipset provides 0.6A per bridge (1.2A peak) with thermal shutdown protection, 4.5V to 25V
And it says that if I need greater mA I can: subsitute SN754410’s (at my own risk) or piggyback solder some more L293D drivers on top of the existing ones. (
Could I begin by increasing the total voltage of the batteries? If they decrease exponentially then wouldn’t starting at a higher voltage give me more time? I opened one of the batteries up. It is made of 3 cells that are inside static bags and taped together. The batteries are soldered together in a series (I presume a series).
Should I use a relay? I have 3. I included pictures. I read a little about them tonight but other than a brief mini-project in my Intro to Arduino kit, I have not used them.
I read a little about creating a voltage amplifier. Then I got so sleepy I stopped.
Finally…. I can simply get different batteries, but I dont know what kind. If this is what I need to do, then I need to get an idea of what kind so that I leave room in the rebuilt robot.
I will do more research and figure it out. I don’t expect you to do it for me. I just feel like I need to know which direction to go. I am afraid if I just try it all until it works I will run out of time.
04.15.17 Robot Plan
Gene has not responded yet. I kind of cornered him at school and asked him very directly “Should I change the motors or the batteries” but he did not give me a straight answer. I know it might not be the best answer, I just want to know which is the most efficient choice since I am on limited time. I am not asking him to do the research for me. I just want a direction.
I took the old robot apart to try and fix it. Also, if I am going to present it as a design project, it needs to look at least “ok.” The old one has too many holes drilled in it from where I had to make alterations. I hate to waste wood and laser time re-cutting an identical robot. I want to fix it.
I researched lots about batteries and motors but I am still confused so I am going to try and redesign without a firm decision.
It did not go as smoothly as I hoped. I ended up canceling my laser time because I knew I couldn’t get anything done.
04.16.17 Robot Plan
I went to school and cut out wheel covers but the laser is acting weird and I am not sure I can cut the robot on the Universal. Unfortunately, all my plans are set to the Universal. I am going to end up at school all night trying to figure out how to set things on the logilase Monday.
I did design the robots wheel covers, which look nice. I needed to fugure that out. I just didn’t concentrate as well as I should have. I am going to have to try again Monday.
I need to finish my frame but I have not.
I need to find a way to make my design even more flexible. I need to be able to cut out the layers and attach components without messing up the design of the chassis. Plus, I want the wheels to be covered. I really dislike the look of them sticking out on the sides. If this is going to the expo as a design project, then it is not going to be very good the way it is now.
Several hours later ….
I think I finally have a base. It always looks so easy when it is done. I feel like I should have figured it out in the first few minutes. I hope that when I learn to use 3-d programs like Rhino, I get faster at this. It is too late to try and go cut tonight. Im not alert enough and I will just fuck it up. Tomorrow I will go get wood for the frame. Then I will cut it out. Then maybe Wednesday I can get the image cut for the frame. Uggggg. I have no statements for these damn projects.
E-mail from Gene:
Can you send me the specs on your motors? I want to know what their amp or watts rating is. I have a feeling that your batteries simply don’t hold a large enough current to power the motors under weight. 12 volt batteries start dipping into the 11 volt range when too much amperage is being pulled out. Like I said when I saw you, if you drop too low, you damage the batteries memory and they can never reach their base voltage again.
I definitely wouldn’t run higher voltage as it will damage the rest of your components, particularly your 12 volt motors. It looks like your motor shield can handle up to 1.5 amps which is pretty high, but I doubt those batteries provide that much current.
Why do you want to use a relay? They’re great as electronic switches that can handle high amounts of voltage / amperage, but otherwise I’m not sure why you want to use one.
I responded and sent him the Specs.
I also sent this E Mail:
If you are correct, as I am sure you are, and my battery cant do what I need it to do with the motors that I have, then the simplest action is to either buy new motors or buy a new battery.
I am researching both now. I found another good source to explain how to calculate the motor specs needed. It makes sense of the math involved more than some of the others but I dont feel like I understand enough to pick. The first time around I decided to just buy bigger motors than I needed because I figured more was better. If I had big motors I would not have to worry so much about weight/incline/wheels etc. Since I wanted a flexible platform that seemed like a good thing. However, I am sure I could find smaller motors. Motors are somewhat easier to change than batteries for my design.
I could also change the battery but I really need to decide that soon since I just redesigned the enclosure and a different shape would probably change everything.
The redesigned robot looks good but I still don’t know if it will work. Gene has not responded. Wade and I tested the motors and now the second set of motors is dead! Wade thinks they are simply a bad design. He says I need much more expensive, better motors. I am so screwed. I guess I will do what I have to do. I will get things fixed enough to look good at the Symposium even if doing that wastes time. Then I will figure out functionality later.