Chassis according to Wikipedia is a chassis consists of a framework that supports an inanimate object, analogous to an animal's skeleton, for example in a motor vehicle or a firearm. According to me it is the skeleton of the robot. The first part of a robot is its chassis. The shape and size of the chassis depends upon the shape of the robot or vehicle to be made. The shape can be circular,rectangular,triangular. Circular and rectangular shapes are most widely used but you can make chassis of any desired shape,it can even be irregular depending upon the application of the robot.
Now it is important to select the material of the chassis. The selection criteria depends upon following factors:
(1) The size of the robot
(2) Budget
The larger the size of the robot the larger the weight bearing power is needed therefore for small robots wood or plastic materials are used for making the chassis.
For larger robots cast iron is used because it is cheaper and weldable(Can be easily welded other metal parts) but only problem is that it gets corroded easily,therefore it is usually painted on all sides. Another option for heavy robots is use Galvanized Iron sheets it is rust free but doesn’t weld. For light weight robots aluminum or brass sheets are used.
Selection of chassis is very important task because it acts as a housing for all other parts such as batteries,motors,sensors,wires and also gives the robot a specific shape.
A Micromouse is a maze solving autonomous vehicle which completes the maze within minimum time possible.
A micromouse has to cross the maze in minimum time therefore to achieve that it should rotate very fast.
A micromouse has the following parts :
1.Body i.e a micromouse's mechanical structure
Chassis:
The MicroMouse chassis is the main piece that holds together all the other parts.
It must provide enough space for the microprocessor, batteries, motors and sensors. The
chassis will be built with an easy to work material like plastic or aluminum. The
advantage of using aluminum would be to draw heat away from the motors, functioning
as a built-in heat sink, but plastic may be easier and cheaper.
The chassis need to be small enough so that is able to make a full turn inside a
maze block without touching the walls.
1.Micromouse should have a Robust and compact chassis.
2. Adequate to allow easy movement inside the maze.
The size constraints imposed by the dimensions play an important role in determining the shape and orientation of finished micromouse.
2. battery or power supply
The power supply can be vary from 5-24 volts and can be of normal lead acid,dry cell or others like mercury cell and lithium ion batteries.
3. Sensors
In the final MicroMouse, two types of sensors will be used. A row of proximity
sensors overhanging the top of the maze on both sides of the MicroMouse will be used to
keep the MicroMouse centered within the cell and for environment mapping in adjacent
cells.
Distance sensors will be used to detect the length of the path in
front, and possibly to the sides of the MicroMouse. These infrared sensors are relatively
low cost, have been used effectively in several MicroMouse designs, and transmit an
output related to the distance to the nearest object within a range of 10 to 80 cm. The
sensors will have to be calibrated to function predictably for varying maze and ambient
conditions
Link to IR Sensors
4.Microcontroller
The microcontroller is both the brain and the heart of the MicroMouse. Because
the device is autonomous, the microcontroller must control everything the MicroMouse
does while in the maze. Based on the inputs it receives from the sensors it must calculate
a path for the mouse to navigate the maze. It must also control the drive motors to move
the mouse and after reaching the goal reduce the path back to the starting square to an
optimal path. The microcontroller board must be low power and the entire board must be
smaller than 25 x 25cm.
The work on the microcontroller can be broken down into different functions:
path finding, movement, sensing, and crash recovery. The path finding algorithm will
receive inputs from the sensors, calculate the best move, then output commands to the
movement functions. Movement control and sensor data gathering functions will be
established early to ensure their proper function and allow ample time for debugging. In
order to combat unforeseen skids and collisions, a variety of crash recovery methods will
have to be developed. As with any large program, the functions can be worked on
simultaneously as long as strict variable passing rules are established before work begins
5. Locomotion
A Steering type drive is used in micromouse just like in cars.
For turns Stepper motors are used,the steeper motor controls the front wheels and for forward movement DC motors are used which controls the rear wheels.
Link TO Stepper Motor:
Related: Ahish Bhatt's Micromouse,Maze Solving Micromouse
| ||||
GET QUOTEThis Innovision was a lot better than the previous one.
This innovision had more technical events.
The participation was at a high.
People from different colleges participated in events like Line Following Robot,Micromouse,Robowars and Carnage.
The new attractions were the auto show,the robotics display(by techtronics).
The event that attracted the most number of people was Nexus (organized by TRI)
The participants had to make a robot thathad to lift 4 blocks one at a time from the ground and place it on a height.
The link to the site : innovision07.com
Here are some pics and videos :
In such cases where we need to control the rotary position of the motor we can use stepper motors. Stepper motors have a tendency to make beginners feel uncomfortable about using them. But lets hope this air of discomfort about using stepper motors disappears once we are done through this article.
Stepper motors are motors available in round, square, rectangular shapes with 4 or more wires coming out of them.
In the permanent magnet stepper motor the rotor is a permanent magnet and the stator is a set of coils which are energized one after another. In the unipolar motors the direction of current in the coil doesn’t reverse (so UNI) while in the bipolar the current through the coil flows in both the directions (so BI).In both types of stepper motors there are two coils wound on the stator poles, which gives us 4 wires.
The difference is that in unipolar motors there is a center tap from each of the coil winding. These center taps are either brought out individually (which will give us 4+2 = 6 wires) or are shorted together and brought out (which gives us 4+1 = 5 wires)
Properties:
1) Digitaly controlled brushless motor that rotate a specific number of degrees (a step).
2) Number of degrees (resolution) can be between .72 to 90 degrees. General purpose steppers have a resolution of 15 or 30 degrees a step.
3) High precision, low torque.
The following figure shows a stepper motor deflected by 90 degrees
This occurs only when one coil is excited and other's are not.
The following figure shows half step where two adjacent coils are excited and therefore the rotor moves in between the coils .
By this we can move by 45 degrees.
| ||||
Line sensor:
AMPLIFIED SENSOR CIRCUIT
Description:
The circuit uses an comparator to compare the value detected and ouput logic ‘1’ or ‘0’ or ON and OFF.
We use an IR LED which will emit Infrared light and it will be reflected by the surface. The detector acts as a variable resistor whose value depends on the intensity of light falling on its surface. The higher the intensity, the lower is the resistance of the detector. The detector and R2 act as a potential divider. When the intensity is high (reflected from white surface), the resistance of detector is low and so the value of the potential is high. Similarly when the intensity is low (reflected from black surface), the resistance of the detector is high and so the potential is low.
This potential is compared with a reference potential. The reference can be varied by the potentiometer (pot). Calibration is required. You have to record potentials of the white as well as black surface and then find their ranges. According these potentials ten set the reference so that for white surface output is .high and for white black surface output is low.
An LED can also be used as a visual detector so that you can see whether the surface is black or white.
R3 resistor prevents excessive current to pass through the LED. The value of the resistor depends on the size and the colour of the LED. More the diameter of the LED , more is the current it will sink in. R1 should be chosen according to the LED. Usually for 3mm Red LED and 5V supply 330Ω is enough. R2 should be larger then the maximum resistance of the detector.
THINGS TO NOTE:
- The LED and detector have very narrow emission and detection angles, so keep them close so that the circuit functions properly.
- Metallic or glossy surfaces reflect more tend to reflect more light, so make sure you calibrate the device properly.
- Many objects are opaque to visible light (that means light doesn't pass through it, like wood, black plastic, metal), but are transparent to IR light.
- If you work in the sunlight make sure it doesn’t interfere with the function of the circuit. Usually sensors placed below the body of the robot are the least affected by it.
- Depending on resistor values, your IR circuit can be tweaked to better detect color instead of distance.
In our college we do not have a real micromouse event it is a joke
It is only a programmed device lacking senses.
In a micromouse the car has senses i.e. it has to traverse the maze in the minimum time possible by using sensory devices.
It requires a lot of brainstorming in making an efficient micromouse.
By an efficient micromouse i mean a micromouse which can to cover the maximum distance in the minimum possible time.
This is a video of the best micromouse made by a student of IIT Mumbai, ashish bhatt
It is a real visual treat
Related: Maze Solving micromouse
How to make a micromouse
Hey Innovision is coming
HERE is the link for this year's site http://www.innovision07.com/index.php
All those who are participating in carnage and/or robowars will find this interesting
This is a hack which helps in fast change of direction of DC motor which can help in fast switch
between forward and backward direction
An H-bridge is a type of circuit that you can use to get a reversible DC motor to spin both clockwise and counterclockwise.
In other words, this circuit allows you to quickly reverse the direction a motor is spinning by using a switch or controller chip to change its direction.
I'm going to show you how to make the simplest and most reliable form of H-bridge that I know how to make. I must warn you that this is by no means the best H-bridge design and, in fact, it has a couple shortcoming which I will explain later.
Although, should you never have made an H-bridge before or simply need a circuit that can reverse the direction of a motor's spin, then this circuit is a quick and easy solution.
This is the link to the instructions to make a H-Bridge http://www.instructables.com/id/EQDILA2F54HOEGE/
Here is the link where the working of the H-Bridge is shown
This is for all interested in ROBOT BATTLES.
Battlebots is a great site.
It has Robots from lightweight to heavyweight
category.
There are some great videos of some of the finals and league matches of BattleBots.
It also has some Tutorials of How To Make A Robot.
The best thing of the site is you get to see some of the best battle robots lifting types and ones with blades and sharp weapons.
Here is the link
http://www.blogger.com/This%20is%20for%20all%20interested%20in%20ROBOT%20BATTLES.
The Defense Advanced Research Projects Agency (DARPA) will hold its third Grand Challenge competition on November 3, 2007.
DARPA will award prizes for the top three autonomous ground vehicles that compete in
a final event where they must safely complete a 60-mile urban area course in fewer than six
hours. First prize is $2 million, second prize is $500,000 and third prize is $250,000. To
succeed, vehicles must autonomously obey traffic laws while merging into moving traffic,
navigating traffic circles, negotiating busy intersections and avoiding obstacles.
The location of the event will be announced on August 9,2007 after the qualification process is complete. The course will involve a 60-mile (96 Km) urban area course, to be completed in less than 6 hours. Rules will include obeying all traffic regulations while negotiating with other traffic and obstacles and merging into traffic.
The Urban Challenge requires designers to build vehicles able to obey all traffic laws while they detect and avoid other robots on the course. This is a particular challenge for vehicle software, as vehicles must make "intelligent" decisions in real time based on the actions of other vehicles.
The winner will receive US$2 million. The second place finisher will receive US$1 million and the third place finisher will receive US$500,000.
The event is being followed closely by auto manufacturers for the implications it holds for smarter cars and safer highways in the future.
We hope to send a team from India for the DARPA challenge in coming years.