How much can your 9V battery support your circuits. If you have a good power motor then your 9V battery will drain in minutes. Specifically when you are driving a stepper motor , it is near impossible to sustain in the contest with a 9V battery.
Use a Li-ion battery for such applications. It comes in mobiles and Laptops and is rechargeable. Though the initial investment is higher , it will give good returns.
“Break them and use them ” this is the Magic Mantra !!!
There’s a sudden rush of viewers on my micromouse algorithm post. I guess all this is since the IITB fest is coming up. well i think there was a pretty detailed explanation of the algo so this post will show you one of a very good micromouse hardware designs.
Complete Design By:
1)Ragavendra Prasad
2)Rahul
3)Ravitej
4)Vanmsi krishnaSame people who buit the mobile controlled Robot
In most contest people using stepper motors struggle to make a confortable run due to the slow speed of the stepper motor and a poor torque . Unipolar motors have lesser power than their bi-polar counterparts but then there are ways to make your unipolar stepper work better than what it does now.
First You can have a look at the stepper motor control mechanism here
so in that post we’ve seen that the pulses are given in the order as below.
1000
0100
0010
0001
Now this will do a good job and give you a smooth running robot. But another good alternative to run your unipolar motor with greater torque and speed is to give the pulse the other way as below
1100
0110
0011
1001
This sequence will do the magic for you. Bu the robot will have a bit rough run compared to the single line sequence given previously.The two line drive will show you how fast your steppers can run with an appreciable torque.
Heard of Rf 433 Khz serial transmiter module? Well once you take it to a contest it may clash with other people using the same frequency transmitter module. Now one inovative idea i saw at the kurukshetra contest was a Address selective Encoder and decoder.
This robot was made for the sumo wrestling contest. As we discussed the concept of only the remote in the previous post on mobile controlled robot the concept of rf trasmition will be discussed here. It was brought to the contest by Vineeth,Santhanam,Sundararaman,Raghuram of PSG college of engineering.
HT12E
Now this is the pin configuration of the HT12 series .It has pins A0-A7 which makes it 8 bits of address. The D8-D11 which is 4 bits long.
So if you need to send four bits of data and you set a particular address selected then the IC automatically generates a serial out of the address bits + data bits.
This serial out from pin 17 can be given to a serial tx433 module for tramnsmission.
HT12D
This is the decoder. The serial address+data trasmitted by the module is recovered at the second part of the module and is given serially to the HT12D IC which correlates the adress set to it if it matches the send address. If so it will paralle out 4 data lines. “This mechanism works much better to receive even when others are using the same frequency” says vineeth.
I’m seeing my blog after days of work. I’m just over with a very busy schedule with my works and projects. This week was very eventfull participating in Kurukshetra “The Anna University techfest”.
There were three contests : Sumo Wrestling , Micromouse ,Triathlon
I came across few bots that i’l talk about here for the sumo wrestling
Sumo Wrestling
This is as simple as fighting with the other robot. maximum torque with the maximum wieght wins the game.Its all pretty simple if you have some high tech mechanism to tackle oponent hits or his push. But finally it boils down to how much force your bot has.The sheer power matters.
But not going into the details of mechanical design and the power and the rating and motors , I was more interested in few robots i came accross on the areana which had cool control techniques. Two more specific ones were a mobile controlled robot and another self designed priority encoder based remote control.
Mobile Controlled Robot
This is the sumo robot that was controlled by mobile phone. Now this is a pretty good way to utilize the available resources to control your robot. All you have to do is call the mobile phone from some number to the one located on the robot.Then keep pressing the keys from the mobile you called and make therobot move.
They used a 100 RPM motor and a metal chassis as seen in the picture. Now how to control a robot using mobile phone iswhat we are worried about . Now have you noticed that when someone calls you and he clicks on his keypad you’l recieve a tone.If you were more concious of that , did u note that each key pressed has a different tone.
Lo you’ve got a transmitter and a receiver. Now all you’ve got to do is decode the carious tones to detect the different switched pressed.These guys used a DTMF tone decoder. HT9170 is the IC used to peroform tone decoding . This Ic gives out 4 bits based on the tones received. once we obtain the digitl data the following process is just a cakewalk. Use a Microcontroller and decode based on those bit combinations received give appropriate signals to the motors. Now that’s sounds really cool and simple.
Now how do you run the motor?? what! you still don get it? just make a call to the robot and make it move
Interupt: Well that literally means stopping you from doing something? well yes that’s precisely what an interrup signal does.When a processor keeps working on some program,You may execue a small emergency chunk of program in case you get a signal form a specified source to a pin.
This can be done by polling But will involve a lotof your processor time.Thus you dont spnd time looking for the signal all the time, instead you set that pin for an interrupt option. So your procesor will keep processing any other program without looking for the signal,But once there is a signal your program will be automatically redirected to a funcation called “INTERRUPT”.
In PIC16F877A the most basic interrupt in on Pin RB0.
The following program will make the interrupt program to execute once there is a pulse at pin RB0. The interrupt at raising edge or falling edge is configurable using software approach.
————————————————————————————-
unsigned short count,read;
char num[10];
void interrupt()
{
TRISC=0×00;
PORTC=0xFF;
INTCON.F1 = 0; /* clear the int flag */
}
void main ( )
{
count=0;
TRISB = 0xFF; /* set up port b */
PORTB = 0×03; /* turn off all and any LED’s on port b */
INTCON.f7=0×01;
OPTION_REG.F6 = 1; /* interrupt on rising edge */
INTCON.f5=0×01;
while(1);
}
————————————————————————————
NOTE: Any program here might have a problem with “X” dou to formatting on wordpress. they all are capital X.
The above program will make all pins of PORTC high once there is interrupt signal from some sensor (say) . Once the interrupt is executed ,the procesor will continue what it was working on prior to the interrupt.
Hey now this should be tried.Its fun and a very usefull tool.
Internet offers you just about anything in robotics. Any circuit any design , its here. But then i personally felt that those are very much unorganised and also not the ones actually done by each of them. there’s a lot of plagiarising. Now this shaastra , Robotics FEST at IIT,CHENNAI. is a key event and i’m planning to individually cover all the robots and the great minds who have built them. If possible with the circuits that they used. So keep hooked to the this page…. in three days you’l find hundreds of posts with a lots of information and news.
