MECHANICAL DESIGN REPORT: OVERHAUL

Overhaul Team ID: 9787

Robot Design:

The chassis is an innovative six legs differential drive. The material used for chassis design is stainless

steel (SS: 304). This material provides good strength with good weight balance between the robot body

and the arms. The design technique basically used is trussed body for maximum weight reduction.

The robot has a drive system comprising of six legs fixed on small wheels. The design is innovative and

makes the robot capable of traversing over irregular terrains.

The robot has a robotic arm for picking and placing the bridge plank and the victim blocks via a hook as

the end effectors. There is also a hook lowering mechanism for the victim blocks at deeper sites across

the accident site.

Mechanisms Used:

Six Legs Differential Drive Mechanism.

Robotic Arm.

Hook Lowering Mechanism.

Six Legs Differential Drive Mechanism:

Components used:

1) High torque D.C. motors:

500 RPM.

12 V.

High torque.

2 Nos.

2) Metallic Pulleys:

8 Nos.

3) V-belt:

6 mm thick.

4 Nos.

4) Spur Gears.

5) Wheels with custom legs:

6 Nos.

Mechanisms:

The drive mechanism used is unconventional yet innovative 6 legs differential drive system. One D.C.

motor drives right hand side legs while other the left hand side legs. To make the control much easier

yet effective and accurate, the power from single D.C. motor is transmitted to the three legs for one side

via a simple transmission system. This transmission system consists of spur gears, pulleys and v-belts.

We are using V-belt in spite of flat belt for the problems and issues related to slip.

The power from the motor is transmitted to the main shaft via a couple of spur gears and a couple of

pulleys it is transmitted to the other two legs. This is same for the other side of the mechanism.

As per our innovative design, our legs are custom fabricated by us as shown in the figure. The legs are

fitted at some distance apart. The middle leg is all shifted double the distance as the other two legs. This

enables the legs to work without collision and also when other two legs are not working in irregular

terrains, then the middle leg will do the work like a lever to lift the bot from the situation and vice versa.

The legs are made with strong material and also it has deep cut threads for gripping in irregular terrains.

Robotic Arm:

Components Used:

1) D.C. motors:

100 RPM.

12V.

High torque.

2 Nos.

2) Spur Gears.

3) Worm Gears.

Mechanisms:

The robot arm used is a basic DC motor driven arm, with transmission of power to the arm by worm and

spur gear pair. The arm has two levers with a hook as the end affectors.

The construction material used is PPC sheet for strength, stability and light weight.

Hook Lowering Mechanism:

Components Used:

1) D.C. Motor.

2) Pulley: Lightweight.

3) Rope.

4) Hook: Custom made.

5) Special wire for rope stability.

Mechanism:

This is a basic motor driven hook lowering mechanism. The motor is coupled with the pulley. In pulley

the special rope-wire arrangement is wound. When the pulley is actuated, the hook will be lowered. The

hook is designed as per the requirements.

Power and Control

This robot is powered by a battery fixed on the robot (12V and 3.2 Ah). The differential drive is

controlled by a pair of DPSTs. The hook lowering mechanism and the robotic arm is controlled by a pair

of joystick switches.

Design By: Satyam, Shashank Shekhar, Roshan Kumar And Prakash Kumar.

College: Sathyabama University, Chennai.