ME 251 Stair Climbing Folding Bot Final Group 6

GROUP 6

Atrij Singhal Faisal Islam

Harshvardhan Prajapati Puneet Bhateja

Ramandeep Singh Rohinish Gupta

Sahil Kajal Sharon

Siddhartha Ravi Vaibhav Sinha

ME 251 PROJECTStair Climbing Robot

The basic idea of our bot is that it climbs the stairs by a series of actions where it folds and unfolds itself and translational motion is achieved by putting wheel and motor which also serves the purpose of differential.

The idea is totally our own and has not been taken from any website.

-group members

FOLDING STAIR-CLIMBER BOT

•  To design a stair-climbing device. This deviceshould be able to climb the stairs for the drawing hall in IITK

• Considerations: Width of the steps: 30cm. Height of successive steps: 12cm.

PROBLEM STATEMENT

• Total Weight of the robot: 554gm.

• A unique folding mechanism

• It works its way up by folding and unfolding its flaps

• The angle between the flaps is controlled by servo motors

• All the plastic flats have been joined together by pin joints with the help of revolute joints

• Motors on the base to help in forward and sideways motion of the robot

• Two supporting bases, each has four wheels, two of which are driven by independent DC motors

• Motor driven wheels have been designed so as to have a good grip on the ground

• One set of motors is inside the chassis and the other outside to avoid interference during movement

The material chosen for fabricating the chassis is ABS(Acrylonitrile Butadiene Styrene), which is a thermosetting plastic which is sturdy and has good fatigue resistance. Moreover, it is lightweight, has good shock absorbing capacity and can be welded easily(laser welding).

MAIN FEATURES

The initial postion is shown in the figure below. Frame 1 rests on the ground. frame 2 will be vertical, while frame 3 and 4 will be as shown.

WORKING PRINCIPLE & MECHANISM -

Position 1

Servo 2 will rotate the frames 3 and 4, upto the next stair (position 2). In position 2, frame 4 rests on ground.

Position 2

Next, servo 1 starts folding the frame 1 towards frame 2. And position 3 is obtained

Position 3

After this, servo 3 starts rotating. The angle between frame 3 and 4 starts increasing. This lifts the frame 1 and 2 upwards. The angle between frame 3 and 4 becomes 90 degree. Hence we obtain position 1 again.

Position 4

Servo Motor - Optimum Torque (6.0V): 7 kg-cm

- Weight : 41 gm

DC Motor - 60RPM 12V DC motors

- 2kg-cm torque

- Weight : 80 gm

Plastic Flats - manufactured from Acrylonitrile Butadiene Styrene, or ABS (density = 1.04 gm/cc).

PARTS SPECIFICATION

STRESS ANALYSIS FOR POSITION 1

SAFETY FACTOR

DISPALCEMENT DUE TO STRAIN

STRESS ANALYSIS FOR POSITION 3

SAFETY FACTOR

DISPLACEMENT DUE TO STRAIN

(mm) Max (mm) Min (mm)

Shaft 8 8 7.987

hole 8 8.185 8.040

TOLERANCE ANALYSIS

1) DC motor shaft and hole toleranceHole - 8D12

(mm) Max (mm) Min (mm)

revolute 5.75 5.740 5.643

hole 5.75 5.811 5.750

2) Revolute joint tolerance

(mm) Max (mm) Min (mm)

2.5 2.530 2.506

TOLERANCE ANALYSIS (contd.)

3) Servo bolt tolerance analysis

4) Servo shaft and hole tolerance analysis Shaft (5.75 h7)Hole (5.75 F10)

(mm) Max (mm) Min (mm)

Shaft 5.75 5.75 5.741

hole 5.75 5.798 5.760

S. No Parts Material Quantity

Unit price(Rs)

Price (Rs)

1 Plastics Flat

ABS 16 100 1600

2 Servo Motor

_ 3 525 1575

3 DC motor _ 4 150 600

4 Wheels _ 4 30 120

5 Caster Wheels

_ 4 20 80

6 Revolute Joint Pin

M.S. 3 2 6

COST ANALYSIS

Total cost = Rs. 3981/-

THANK YOU