Electro-mechanical solenoid for robotic shooting mechanism

Replies

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  narayana murthy

  yes buddy u can but permanent magnet may lose its property after some days it may create problem so i choose ferro magnet material
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  abs_vicky

  Thanks a lot Mr Murthy, I m designing an electro-mechanical solenoid. Its input is DC current. But, my guide asks me to mention its voltage rating. What is this and how to find it out?
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  narayana murthy

  i think he mean that the voltage at which it needs to work try to know total resistance and current on it as your saying it takes dc current i*r will give u voltage rating
  this is iam thinking if iam wrong correct me
• 

  aj_onduty

  Dear vicky,
  Isn't it too early to mention its voltage?
  Now, for this to be said, We need to find out all things first. That is, everything you need to know to finalize the parameters of the robot.
  I give you a very rough questionnaire to be filled by yourself.
  1. The main components you will need.
  2. load it has to carry(the weight of the 'hand' it has to move at a high speed, for an impulsive action to be hit at the ball), at what speed, and how much momentum to be transferred.
  3.What ratings of the equipments are available in the market(standard)
  4.What other factors are to be considered?(natural)
  Please don't seek the help of the teacher who asks the rating first before even asking what homework you did.Please seek help of someone who can really help you. 😀
  Thanks.
  If you think that I was informative, please thank narayanamurthy. He is the one who showed me this post of yours.
  @nm, was caught up in work. That is why I couldn't respond quickly.
• 

  narayana murthy

  @aj,
  its k aj actually i don't know much about robotics so i asked you to post in this topic any thanks for replying
  @vicky,
  i think post given by aj may be help you
• 

  abs_vicky

  Thanks a lot to both of you guys!!
• 

  abs_vicky

  See actually my robot is basically a line-follower with a shooting mechanism.It has an on-board mechanism of storing ping pong balls which it has to shoot. My shooting range varies from 3-7 feet(91.4---213.36cm), It has to shoot at 10m/s with a current of 60 A and has 800 turns, length is 20cm and 5 cm diameter and weight 2kg, can anyone of you plz tell me the relation of the Current through the solenoid with the speed of the ball if the mass of the ball is m(2.7 gms) , The general formula wud b gud!!!
• 

  aj_onduty

  Dear Vicky,
  Please answer my following questions.
  1. Where did you get all this information? Did you get it from your prototype or did you copy it from somewhere?
  2. Which year are you in?
  3. Do you want this robot to just shoot the balls from its ball-store or do you want it to play ping pong, that is hit the ball coming its way?
  4. Did you look into similar applications in like the electric bell (look in Wikipedia) or any others using electromagnetic induction for mechanical motion?
  5. Can you tell me a few things about where you reached in the project, and a small description of the project? I really want to help you for this. 😀
  Hope to see your answers soon.
• 

  abs_vicky

  No, I got all this information from a tutorial given by the organizers of the competition. Actually, our robot is essentially a line follower with a shooting mechanism. It has an on-board facility of storing TT balls and has to shoot them to a light source and hit it from behind walls placed at various locations. It only has to shoot balls and hit the target(light source).
  (#-Link-Snipped-#) (plz follow the link to get pictures of the arena). So , our bot has a sensor circuit ( LED-LDR) to follow white lines in a black background. It has 2 IR sensors to detect a wall in near the path when a wall arrives. It has been programmed to stop then. Another LED LDR array is fixed on the turret of the bot and has been calibrated to find the distance of the bot from the target and causing the turret to rotate requisitely. This information is passed to the microcontroller(Atmega 16) . Next, we hav a PWM which produces digital voltage pulses with the required duty cycle . Next, we hav a DAC converter to get analog signal for the voltage. Then , we hav a MOSFET amplifier to change the output to current ( from voltage input) and this current is fed to the solenoid.Plz guide me if I am doing something wrong??? or tell me if any other way exists.... Our microcontroller takes care of three things ( line following, obstacle detection i.e.- detecting the wall, and varying the duty cycle of the PWM to vary the voltage in order to vary the current and finally to vary the shooting force of the solenoid. Can u plz tell me the relation between the force imparted by the solenoid and the velocity of the ball(mass m)?? Thanks in advance!!!
  
  Regards
  Vicky
• 

  narayana murthy

  nice trying bro but here your using the solenoid for short time so permanent magnet is suitable for this purpose because it releases more power than other magnetic materials but main problem is permanent looses energy after some time here no problem because you use it for short time thats all i know
  and this may help you for your relations
  Force
• 

  aj_onduty

  Its so exciting that I would like to be there. It is so good. I love to make my brain go crack-crack in this type of a problem.
  Why use a solenoid, when there are different methods of approach?
  We can use a motor-spring arrangement here. That is, we can use a motor to wind a spring and when we find it ready to be launched, we can propel the ball to the target using the force in the spring. No need of calculating the magnetic components and all things. I, personally used to bunk the magnetic field theory classes, and I hate magnetic calculations 😁
  Coming back to the topic, why don't you work this out, it is not a hard thing. We can lock the spring in a lock which can be unlocked by a "fire" signal.The lock can be anything, a very small motor which can rotate in both directions(use H-bridge IC L293D for that). We just need a motor powerful enough and a hammer like object which will move and hit the ball and propel it. We can sett some 4-8 levels(we do not want accuracy, we just need to wind it to an intermediate length. If it is 3-7feet, you can break it up to some 6 parts.) Just think over it and lets make this thing shoot out. Anything you do, please let us know. Excited about the whole thing!I just want to help. 😉
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  aj_onduty

  There are even other ways for locking it to a range where ever we want! But first tell me if you are interested in this thing.
• 

  aj_onduty

  Here is one method.
  Remember the door locks which can close when pushed but you need to turn the knob to open it? Use something similar to that.
  Lets imagine a trebuchet. Now, we are going to add something new to the traditional trebuchet mechanism here. It is known as the spring locker(that is what we call it in here). Make grooves in the body where the bolt of the locker can get in. The bolt is to be normally out. The locker can wind in its bolt anytime when you give a command to do so. That means it will get unlocked.
  I hope you didn't understand the thing, so I am enclosing one picture of my idea.
  
  When we wind the spring, the trebuchet goes clockwise(see pic). The bolt gets into each groove till you feel that the range is enough(magnetise the bolt and place a level switch(reed switch) near each groove. You can detect where the bolt is). When the bolt is in the desired slot, just stop winding and turn off your motor. Then, energize the "unlocker" solenoid which would pull the bolt just enough to unlock the trebuchet. The trebuchet lets the ball go bang to the place you want it to go.
  Hope you understood the whole thing.
  And one more thing, hope you understand the handwriting. 😉