Mechanical Spider

Problem Statement

It is difficult for humans to reach in compact places, or during search and rescue operations in disaster areas. So there is a need to design a robot with leg moving support mechanism with low cost and simple mechanism which can carry out the operations. Which can be easy to operate and effective for carrying out the operations

Abstract

I decided to implement linkage based locomotive systems on standard load carrying automobiles as a replacement for the conventional tyres.

The first mechanism which I came across for such purpose was Klann mechanism which actually mimics the motion of the biological organism (crab).

As we know the wheels are ineffective on rough and rocky areas, therefore robot with legs provided is beneficial for advanced walking vehicles. It can step over curbs, climb stairs or travel areas that are currently not accessible with wheels. The most important benefit of this mechanism is that, it does not require microprocessor control or large amount of actuator mechanisms.

In this mechanism links are connected by pivot joints and convert the rotating motion of the crank into the movement of foot similar to that of animal walking. The proportions of each of the links in the mechanism are defined to optimize the linearity of the foot for one-half of the rotation of the crank. The remaining rotation of the crank allows the foot to be raised to a predetermined height before returning to the starting position and repeating the cycle. Two of these linkages coupled together at the crank and one-half cycle out of phase with each other will allow the frame of a vehicle to travel parallel to the ground.

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This project is useful in hazardous material handling, clearing minefields, or secures an area without putting anyone at risk.

Introduction

Early Walking Machines History

History records many attempts to create machines that use legs in place of wheels. The following lists early walking machines that have been identified during research.

In the year 200AD the china maker Zhunge Liang was designed a walking mechanism i.e. wooden ox, a transport vehicle used for military supply. Something it refers to the wheel barrow.

In the year 1770 the UK maker Richard Edge worth was designed a walking mechanism i.e. A wooden horse with eight legs, capable of leaping over high walls. In spite of forty years work and hundreds of models, he was never able to make the idea work.

In this year 1968 the U.S.A maker General Electric was designed a walking mechanism i.e. Walking truck. That could climb over large obstacles.

In this year 1976 U.S.A maker Frank & McGhee was designed a walking mechanism i.e “Phony Pony”. First computer controlled walking machine

Klan’s Linkage

Linkages can be made to provide almost any movement required. These movements can often be quite complex, but few linkages can match the complexity of those walking linkages created by nature-legs. Joseph Klann emulated the complex movement of a natural gait with his exquisite linkage, patented in 2001 (Klann, 2001).The Mechanical spider robot is based on Klan’s mechanism. The Klan’s mechanism is a planar mechanism designed to simulate the movement of legged animal and replace the wheel rotating motion. The linkage consists of the frame, crank, two pivoted rockers, and two couplers all connected by pivot joints. It has 6 links per leg. The pictorial representation of the Klann mechanism in Figure.

Klan’s Mechanism

The leg will rotate by a wheel in rotation of crank. The step height is achieved by rotating the connecting arm which is attached to the crank on one end and the middle of the leg on the other. It pivots on a grounded rocker .The proportions of each of the links in the mechanism are defined to optimize the linearity of the foot for one-half of the rotation of the crank. The remaining rotation of the crank allows the foot to be raised to a predetermined height before returning to the starting position and repeating the cycle. Two of these linkages coupled together at the crank and one-half cycle out of phase with each other will allow the frame of a vehicle to travel parallel to the ground .The Klann linkage provides many of the benefits of more advanced walking vehicles without some of their limitations. It can step over curbs, climb stairs, or travel into areas that are currently not accessible with wheels.

Components

Crank

A bent part of an axle or shaft or an arm keyed at right angles to the end of a shaft by which circular motion is imparted to or received from the shaft or by which reciprocating motion is changed into circular motion or vice versa

Rockers

It is an oscillating lever that conveys radial movement from the cam lobe into linear movement

Couplers

Couplings are mechanical components used to connect two in-line shafts to enable one shaft to drive another at the same speed

Objective

• To design a eight-leg moving support mechanism which can be used where humans are not able to access due to compact regions.
• To design a eight-leg moving support mechanism with high strength and simple mechanism
• To establish a mathematical model for an octopod robot using Klan’s linkage.
• To study the effect of variation of coupler angles on the gait pattern of Klan’s linkage.
• To study the effect of variation of angle of leg link on the gait pattern of Klan’s linkage.
• To achieve a peculiar combination of linkage parameters corresponding to an optimized gait pattern

Methodology

Applications

Toys could be created that would fit in the palm of your hand and sufficiently extensive to convey a battery and a Small engine. So it could ride into battle with radio-controlled ambush insect bicycles.

The military, law requirement, touchy Ordinance transfer units, and private security firms could likewise profit by uses of the insect bicycle.

It would perform extremely well as a stage with the capacity to deal with stairs and different deterrents to wheeled or followed vehicles.

It could be customized to watch a predefined edge indiscriminately interims.

Unmanned activities could be utilized for surveillance, watching, risky material dealing with, clearing minefields or secure a territory without putting anybody in danger

Recommendations/Future Works

This mechanism can be made more flexible by using different link lengths for front, middle and hind legs. Intelligence can be induced by introducing Sensors and vision to improve the effectiveness of this robot in future. Range of motion and moments available at each joint are the greatest concern as it is important for achieving stance and insect like walking

Conclusion/Results

Eight-leg moving support mechanism is developed using simple Klan’s linkage mechanism. It is electro-mechanical mechanism which can also run on batteries. Eight leg walker can be operated on uneven or rough surfaces. It can access compact places were humans cannot access. Strength of six leg walker is high so it can also be used for carrying loads on uneven surfaces. Adding night vision cameras and obstacles detecting sensors to the Eight-leg walker it can be used for surveillance at night. Eight leg mechanical spiders can be applicable for the making of robots. It has a wide range of application in the manufacturing of robots .It is also applicable in the goods industries for the small transportation of goods inside the industry. The mountain roads or other difficulties where ordinary vehicles cannot be moved easily can be replaced by our six leg mechanical spider

References

1. Manufacturing of Six Leg Moving Support Mechanism (www.irjet.net)
2. www.mondospider.com and Fabrication of Kinematic Robotic Walker with Left and Right Motion (www.internationaljournalssrg.org)
3. Mechanical Spider by victimization Klann Mechanism, Miss. Suman Sharma (Chhattisgarh Institute of Technology, Rajnandgaon)
4. Analysis Of Theo Jansen Mechanism (Strandbeest) And Its Comparative Advantages Over Wheel Based Mine Escavation System ,Swadhin Patnaik (SRM University, Chennai, India – 600026)