4 Practical Part

Figure 4.1 Crawler mechanical designs

4.1 Equations and analysis

The belt circumference needed in every stage of this design is variable when the planet wheels change its position as shown in figure 4.2 and 4.3, so when we need to choose the belt, we must calculate the belt length required at take care this point.

Figure 4.2 The main arm in horizontal position (minimum belt length required

Figure 4.3 The main arm in vertical position (maximum belt length required)

We choose the value of the radius of the driver wheels depending on the velocity Which we prefer to be less than (25 m/min), so we choose the speed of the motor to be 60 rpm (which is available) and the maximum velocity (25 m/min) then :

( RH :  is the maximum driver wheel radius we need to have the maximum velocity )

So, we must choose RD less than (6.6314 cm) to have velocity less than 25m/min.

We choose RD = 6.25 cm .

The physical dimensions for mechanism used in experimental part of our project are shown in table 4.1 below:

Figure 4.4 Mechanical system parts

Table 4.1 Practical values for the mobile robot

Belt length can be calculated as follows:

1. The minimum belt length can be calculated from figure 4.2 as:

Minimum length (Lmin) =  2 [ BE + EF + FC ]                       (Eq-1)

2. The maximum belt length can be calculated from figure 4.3 as:

Maximum length (Lmax) = AC + CB + BE + EF + FA            (Eq-2)

Where:

4.2 Calculations of the practical design

The calculations show that the length of the belt (circumference) required in the vertical position is longer than in the horizontal position.

Substituting physical values in equation 1, we obtain:

LMIN = 2 [45 + (50 - 22.5)] + (3.14 * 6.25) + (3.14 * 2.75)

= 173.274 cm

And substituting in equation 2, we obtain:

LMAX = 3.14 * 6.25 + 45 + 2 * [(22.5 + 6.25) + (50 + 2.75) ]  

      =184.787 cm

 

To solve this problem we choose the length of the belt depending on the horizontal position(L_MIN) and we put spring on the main arm to correct the increasing of the belt distance needed in the vertical position.

 

Figure 4.5 Spring position

 

Here we finished our project ( Tele - Operated Robot).

RESULTS AND RECOMNDATION

1-      We believe that crawler mobile robot design will allow us to solve many of the problems associated with obstacles such as stairs, roughness…etc.

2-      It's recommended in feature to continue and improve the software used in our project by using  Image Processing or Voice Processing methods and improve the radio frequency link (RF transmitter and receiver ) by solve the noise problems and increasing the range .

3-      Despite the difficulties and obstacles faced in accomplishing our project, all the group members found this to be an important learning experience from a technical point of view and cooperated to solve the problems by arrangement the tasks.

3 PIC Microcontroller & Wireless Transfer

3.6    Wireless Data Transfer

3.6.2 Transmitter (TX)

Figure 3.10 Transmitter IC

Table 3.5 Pin description for transmitter

Table 3.6 Technical Specifications for transmitter

3.6.3 ANTENNA

For 433 MHz frequency we have three type of antenna shown in Figure 3.11

Figure 3.11 The types of antenna

Next we will see the Practical Part...