Tennis ball machine DIY - part 2
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- Опубликовано: 25 фев 2014
- After several months of hard work ;) I hereby present an update on my home-made machine.
New features:
- construction is now stable, has rubber bands so it won't damage the floor
- significantly less vibrations
- added ball feed tube, now it won't accidentally tear off an arm
- electronic adjustment of rotation speed of each wheel (in a closed loop, PID controllers, opto-couplers and slot discs)
- electronic adjustment of vertical angle
- can be controlled with switches and buttons
- can be controlled remotely (currently with cellphone over bluetooth)
music:
"Cold Funk" Kevin MacLeod (incompetech.com)
Licensed under Creative Commons: By Attribution 3.0
creativecommons.org/licenses/b...
"Repercussions" by JewelBeat.com 
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Very impressive, I look forward to seeing part 3 when you've added your improvements!
You are awesome...I am a Romanian strudent that just finished Industial maintenace Technology.. and last year i started to play tennis and i love it.. i would like to built a machine like yours as well BRAVO! I take my hat off!
Well done, I'm impressed. I'm also interested in building something like this and will follow: looking forward to seeing the "completed" unit (because nothing is ever really complete!)!
What are your wheels made out of and how much do they weigh? Much appreciated
that is AMAZING!
Waiting for part #3
I've been looking into building my own tennis ball machine, and I'm just wondering what/how you chose to measure the RPM? I have most of my other ideas figured out, just locking down the measurement step for a fairly accurate input to the PID control.
Any chance of sharing your project as DIY? I want to build an ice-hockey puck shooting machine... Or at least the parameters of your motors?
Great project! Will you also try to implement ball spin (top spin, back spin) maybe by varying the speed of one of the wheels?
Nice project! Do you have a link to the motors or some information about them? I'm wondering what wattage/rpm I'd need. And how are you reading the current speed of the motors? Thanks!
you displayed lot of hardwork and imagination for designing machine, Keep it up...
first of all congrats.and please could you inform me about the type of the electromechanical cylinder do you use and is there his cao design
amazing and inspiriting job. I am trying to make my own machine and I am not sure how to push and pull the engines estructure. You did it with a rotary engine but, how do you connect and link the engine support to the estructure? could you please help me? Thanks in advanced
Amazing project. Coud you please send me a part list? Which h-brige and motor specification did you use? Tks
Hi There
Great work on this project !
A quick question - is there any chance you plan to release a parts list, drawings, etc so we can all participate in building our own machine ?
Where can I get motors like the motors in your prototype? which are the specs? I need to build a tennis ball machine like yours for a college project and I have a few doubts yet with the motors
Fantastic project. Any news on the progress (and possible open-sourcing / instructions)?
Hi, great work! Is it possible to get some plans and software from you to build an own machine?
What kind of wheels are you using? And however woul you say that this is ping to cost overall when it's done?
Hi
0bo0, very impressive project!! Can I ask you which motor shield you've used to control this powerful motors from Arduino?
Thanks!
What kind of wheels are you using? And what would ou say the overall cost will be?
Hello! At the end, which rotation speed was the best to play in court?
what type of wheel are you using and can you find tell me where I can find then. Also I love to machine!!!
Please can you provide specs of the motors as well as a guided break down of how you made this...very interesting project mate👌.Thanks for sharing
Hey man, I'm building this at home, I already have those exact motors and i have them running but I'm having some trouble with designing the frame. is there a way I could get in touch with you and ask for some advice?
hi, so you can control the speed of these motors ? they are not "fixed" like with most of CC motors
Hi Nice job, what kind of battery did you use?
nice work did you get patent for it or out in the market yet
Sir 0bo0 , Just asking if you sell this machine? thanks for the reply
Looks good, did you consider hand truck wheels? I would think they could be balanced with normal wheel weights
hi, can i know what kind of batteries you used? and the duration of the game? thank you.
what kind of PID controllers are you using?
hai obo0 i want to make tenis ball machine , what part do use ?
blok diagram
how the tools work ?
thank you
Is there open source porject for this work, can you share devices, equipment and codes ?
Do you have a parts listing for this awesome project?
I wish i had this kind of machine when i was kid playing tennis. But right now my son plays. so i will try to build that kind of machine.
One question which motor did you use at 1:33? can you please share the link where to buy it? did you use the same motors for vertical and horizontal move?
What is the maximum speed with this specs?
awesome. great work.
What about the promised progress?
I really see a good ,and more important, feasible concept for a ball machine.
Maybe you could give us some infos about your Hardware, which motors did you use, which controller, i would really appreciate it as i am planning to make my own machine.
hello there, did you finish this one? Can you provide instructions to build one?
Hi there! Good machinne!!! I would like to know the caracteristics of the main DC motors. Thanks bro!
Thanks for sharing, good work
Hello! Could you please tell me what is the distance between wheels?
Also where did you get that wood?
Hi, Did you finished the Project? Are you selling it? I would like do make a machine like that for my personal use...
I am a part of research team at a university. We would be interested in using your machine for testing golf balls? Is it robust and repeatable enough to test a golf ball?
You said that you use driver BTS7960B 40A, it means based on first cim motor dc datasheet your torque less than 173.4. it is correct?
any idea of where I could find those wheels?
Polak Potrafi :)) BRAWO!!:)) Zamawiam jedną sztukę tej maszyny :D
also how much rpm does the motor have?
Hi, Bro
How to get more information for this machine, pls send me the web link......., What was the finishing product.
what motors did you use?
how much weight is your wood wheel?
hi, can you please tell me where did you get the frames. Specially the "U" shaped stand. I tried making myself, and they are not of precise measurement, so there is lot of vibrations
Metal support parts were laser cut. High precission of rotating parts is very important. Took me quite a lot of time to balance the wheels
Any chance for making this for customers? I'm looking for a cheap tennis machine
How far the ball can go on max/speed of wheels?
Hi Bo,
well done on the great work. I'm pretty familiar with most aspects of what you are doing electronically but I just have a couple of questions on the app development and remote comms.
For someone who is not experienced in developing apps, what is the easiest way to create an android or Iphone app like what you have with simple buttons for increasing/decreasing speed of motors and tile angle?
I presume the Bluetooth comms you are using is equivalent to doing a serial read/write on an RS232 port once the Bluetooth channel is setup?
I notice you are using an RC controller at the end of your video to control the tilt angle. What is the RF transceiver module, which is connected directly to the H-Bridge module, that you are using to communicate with the remote RC controller (Turnigy)?
Thanks,
Paul
Hi Paul, thanks.
I don't want to recommend anything for mobile development because I'm not feeling competent in this matter, but my app was created with Xamarin and it wasn't difficult at all.
Bluetooth module is transparent to the microcontroller, works as a simple serial (RX,TX,GND).
RC RX component on the video is "eleres" - it's a polish 433MHz transceiver based on RFM22b module.
Hi, congratulations!! I liked very much.
Would you tell me?, what kind and model are the motor's dc for pitch and roll.
Thanks very much!
Banebots FIRST CIM 12V 5280 RPM 345 oz-in Brushed DC Motor you find them on www.Robotshop.com or on Andymark.com with a 8 mm shaft check for specifications on the two sites.. i found it less expensive on www.Andimark.com
Hi Bogden, do you have any interest in documenting the assembly of your tennis ball launcher? do usłyszenia z canadé.
Hi 0bo0, Meaning do you provide instructions to build one? thanks..
First of all I must commend you on the work you have put into this machine, well done sir! I am curious about the size motor used for the elevation of the ball launcher, is it stepper/servo? Also how did you connect the threaded bar to the motor shaft?
Thank you.
Thank you. It's a DC motor, several tens of watts power + potentiometer on axis of rotation (for absolute positioning). Motor shaft is connected to screw by a cylindrical coupling part which has a two holes on both sides, one that matches shaft and the other one has the same thread as a rod. Screws perpendicular to the axis secure the connection.
After the tests I found that this mechanism works pretty well but it is not very precise and I don't recommend it. I'm going to replace it with something else, probably a motor with gearbox.
Do you have one for sale?
very very clever....congratulations, i struggle to open a can of coke...thats the extent of my mechanical ability...this is extremely impressive well done!
Hi! How's your tennis ball machine after those years?
which motor you are using
Hi!!! Did you finish it? :)
is the machine ready? where can we purchase it?
Anyone try this project with brushless motors yet? Just wondering if the efficiency increase would give longer run times or faster shots. I'm primarily looking at doing this for pickleball, which is much lighter weight ball and may not need quite the torque required for tennis balls. Also doesn't need to compress the ball as much, so wheel spacing and placement will be different. Just curious if anyone has done this.
It looks awesome now!! Are you going to use servo motors for horizontal movements??!!
Thanks. Haven't decided yet but I think about low rpm/high torque dc motor+gearbox+potentiometer. So basically a DIY servo :)
Hi Bo, still waiting for PART 3
:D
Are there news?
Can you share project details ?
hello Bo
have you got some SolidWorks files to share ?
hi,good job,im from iran,i want too make a machine like you,plz say all information about youre motor,like:ac or dc/power/spin/torque/speed and other info.tnx
hello
I have the same model reconstructed and would like to know which battery you use it.
battery make/model?
Thanks for the tip
Hi. Two 12v 7Ah ups batteries.
Hi! is there a part 3?
hello, by any chance could you explain how you mounted the motors to the wheels, ?
Hello. imgur.com/POTDarx it isn't the best way probably
Yes I guessed as much so. Well that’s the world we are in. I have looked all over the world and even the Chinese ones are the same price. For me I just want to play tennis and want a machine to improve my tennis and as a means to keep a little fit. Not that I am any good but its gets me out most days when the weather’s OK. T
he best machine on the market today seems to me to be the spitfire without going into the professional level.
I would still love to get a start by seeing all your sketches and or notes. I am not looking at it from a profit making aspect.
I am green when it comes to the electronics but my gut tells me that they can be controlled a bit like a macro in Excel. I am in the dark as to how the spins are done. How the wheel spin spin should vary. If an additional angle would create a side spin. The demonstrations you did pitched the ball well. Would it be good for me even as it is now? Undoubtedly. I would lust love to have a crack at making it.
I was looking at a second hand 15-20 year old Tennis Tutor 4p which was the best they did at the time. I spoke to the manufacturers in the states. Extremely helpful. They said based on the diagnosis that the battery was dead as that model was not designed to run off the mains and did not come with a smart charger. The chap had examined on a big screen the frame, control panel, remote and even the wheels. His opinion was that all was well. But this sold as broken for repairs for £350. The world has gone mad.
All the best and thanks for such a quick reply. Oh and I am getting into the music.
Jacky
Hello!! First of all: great work!! Very interesting!!
And thank you very much for sharing these 2 videos.
I'm trying to build a similar tennis ball machine.
I've put togheter all the data you posted in the comments:
electric motor: FIRST CIM 12V 5280 RPM
(12v - 5280 rpm - stall torque 2424 mN-m)
wheel weight: 750 g each (ideally less than that)
distance between wheels: 3.5 / 4 cm
In a past comment you suggested to use a less powerful motor with approximately these specs (100-200W, 3500-5000 rpm under load and long shaft).
My concern is that the power of the motor you really used is approximately 8 times higher!! I'm definitely an amateur when it comes to electonics so maybe I'm wrong, but here are the numbers:
P (watt) = torque * 2*pi*rpm/60 = 2,424* 6,28* 5280 / 60 = 1340 watt (= 1,3 KW)
As you see, it's 1340 W versus 100-200 W.... Which is right?
Moreover, at the same amount of rpm, with 150 W, the torque woul be 8 times lower.
I hope you can point me in the right direction ;)
Anyway... GREAT WORK!! Bye
Hi! Your calculation is wrong. Stall torque means 0RPM. There's a datasheet for this motor on the Internet, it contains rpm/torque curve. According to the document maximum that the motor can deliver is ~343 watts of output power at 49% efficiency. But much less is needed to keep the wheel spinning at a constant rpm.
Where can I get those wheels??
You effort is impressive, any idea from where to get the commercial bowling machine wheels ?
Thank you. I would ask machine distributors/shops, maybe they sell replacement parts.
nice. i am less nervous watching you guys feed balls into this version :)
How do you call this concept?
Hello, what is the diameter on the wheels?
Hey brother, did you ever complete the machine? Would you share the plan? Cheers :))
Hey Bo0,
How heavy are the two wheels you are using ? I just want to know how much the current due to the load you are putting on. And also What kind of batteries are you using to power the motors? UB12120?
Hi very impressive too. Any chance you give us you code and material list? Regards
Hello,
Whats the name of the motor by time: 1:33 ?
I would appreciate an answer
Thanks!
Linear actuator
Hi , Great job man (y) . can I know how to reduce motor's vibration?
Thanks. Dynamic balancing - spin the wheels up (one at a time) and check vibrations (a phone with an accelerometer can help here). Then add some mass on a rim and check again. Move the mass around until vibrations are smaller. Once you figure out what's the optimal place try bigger or smaller mass. I used small coins and a duct tape.
whats the top speed?
que motor tiene?
Hello 0bo0..Fantastic work...Whether it is possible for you to share DC motor specification for vertical Inclination along with rpm ..Thank you very much
Hello. NB4056A@12v. But that motor choice was a mistake. Couldnt achieve good precision with it. I think a similar size stepper motor should work much better
Hi OboO,
I am trying to build a same type of machine.I am considering a 12v 2A 5Ncm DC motor and L298N motor driver.I am expecting your suggestions....
Na it won't work the torque is very less they had used 25 kgcm torque
i like this music!!!
Interested in your ball machine where can I find you to talk privately
would you provide instructions to make one of these ball machines. Can pay you for your effort.
Hi Bo
Sorry to bother you again but I am really struggling with the PID aspect of the program. I can enter the rpm value that i want and the motor spins up but it never seems to achieve the required speed, it always seems to oscillate around the speed and goes faster and slower without getting stable.
I am not sure if it is the way I am measuring rpm in the code or the values I am using for Kp, Ki and Kd. I have tried varying them and even setting Ki and Kd to zero but I still cant seem to achieve steady state.
How many interrupts do you have on the encoders wheels that measure the rpm? From the video it looks like there is only one slot?
If you can share any of your code for this part I would be very grateful.
Thanks a lot
Chris
Hi Chris, sorry for such delay in replying, I don't know if you solved the issues yet. Tuning PID may take some time. I spent couple of evenings on fine-tuning but my settings aren't perfect too. I have only one slit - 1 interrupt per rpm. I had to add debouncing code because I was receiving wrong readings sometimes.
If I set too low rpms my control algo isn't precise too (oscillations). Behaves decently at half a thousand+. You can try to use two (or more) 'profiles' for PID settings, and apply them depending on required rpm value or amount of required change.
0bo0 Hi Bo
Thanks for the reply.
I have finally got my test system working after trial and error with the PID settings and also following your suggestion about having two profiles for PID values depending on the error value. As you say it is not quite as accurate at lower speeds but it gives me hope to start the assembly and metal cutting. I have found that four slots on the encoder wheels give me good accuracy on the rpm meausrement. I havent looked at de-bouncing code but I might need to once my final system is assembled as I have exactly the same motors as you.
I have used an IR rermote control to control motor speed as it was simpler that bluetooth although I might try that later. I will also add direction once I have the basic frame constructed.
Can I ask what type of motor you used for the elevation change? Is it a servo or just a low speed geared DC motor?
Thanks for all your help so far.
Chris
How fast ball ?
0bo0 Nice work. I like it. Beach Tennis is like tennis but on the sand. I would like to make a practice court with home made machines like yours. I wonder if you have a way I can use your idea to build this court. The machine must be at about 8 to 9 feet high, some times lower and should be able to shoot balls straight or straight up for lob shots and should be able to carry a basket with 50 or a 100 balls with automatic feeder. Do you have a part list that you would share. Do you sale the complete package??Would you help me build this machines??.I would like to build a Training Beach Tennis Court with 4 or 5 of these machines that can be programmed to shoot balls in a specific sequences simulating a real game, if you know what I mean. Maybe it is crazy but I know it can happen. Let me know please. Thanks. ezio.
hi OboO, what kind of H-bridge did you use??
Hi. Bts7960 based module from ebay
+0bo0 Thanks for quick reply, In your first video you showed the tennis machine in design view (autoCAD sketch) or something like that, can you please share it. thanks in advance
Hello oboo, please only tell us what are the specifications of the motors...... please please it is an excellent proyect congratulatios you are smart
+Etiel Natan Hi, the motor spec is about 5300 rpm at 12v, free running current 2.7A, stall current 130A
Fantastico