Learn how and when to remove this template message Underwater walking robot, using Klann leg linkages in laser-cut and anodised aluminium. The linkage consists of the frame, a crank , two grounded rockers , and two couplers all connected by pivot joints. It was developed by Joe Klann in as an expansion of Burmester curves which are used to develop four-bar double-rocker linkages such as harbor crane booms. 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.
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But people and animals using their legs can go almost anywhere. The main aim of the walking mechanism is to develop rough terrain robots by capturing mobility autonomy and simulation of living creatures. Such robots can travel like living creatures in stepped stairways household clutters limit the utility of wheeled vehicles. Machines consist of a number of mechanisms for their successful operation and to give the desired output.
Mechanisms like four-bar mechanism, single slider crank mechanism, double slider crank mechanism, etc, are used for transmitting motion, force, torque etc.. The analytical data can be used for reference purpose to design a walking robot to attain better design qualities. There are many types of walking mechanisms but there are two major mechanisms implemented to their best. KLANN linkage is an expansion of four-bar mechanism. It was first developed by Joe Klann in And also by using a designing software called CATIA, we are going to design a 3D model of the walking form and simulate them.
Project Eye: In order to observe the stress distribution in the kinematic links of leg mechanism to get a safe design of walking robot. To know the velocity and acceleration of each kinematic link in leg mechanism. But our future prospect is to replace the wheels with the leg locomotion in terrain robots to go anywhere where the wheels cannot go. This Klann mechanism is a planar mechanism converts the rotary motion of the crank to linear movement of the foot for one-half rotation of the crank and raises the foot for the second half, returning it to the starting point.
Two of these linkages, degrees out of phase, will function as a wheel replacement. It was designed to simulate the gait of legged animal like spider and function as a wheel replacement. Here the wheels can be replaced by either four legs or six legs sometimes eight legs is also possible to design a terrain robot. The Kann linkage consists of the frame, a crank, two grounded rockers, and two couplers all connected by pivot joints.
It has 6 links per leg. Which designed by Theo Jansen to simulate a smooth walking motion. Jansen has used his mechanism in a variety of kinetic sculptures which are known as Strandbeests. There are many types of leg mechanisms are there such as Eight-bar leg mechanism, Strandbeests applied Jansen linkage , Tokyo Institute of Technology walking chair, Ghassaei Linkage Tchebyshevs plant grade machine.
But out of them, Klann mechanism and Jansen mechanism are most popular and best in design. The above Pictures shows how the links connected to other links and how they can simulate.
These walking robots can go anywhere like living organisms like terrain areas and rocky areas and muddy surfaces. 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 a large number 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. It would perform very well as a platform with the ability to handle stairs and other obstacles to wheeled or tracked vehicles. This walking robots can be more advantageous than wheeled robots and can go anywhere like as humans and other organisms like spider and crab and cockroach.
There are so many types of walking robots. That above picture shows the some of the walking robots which are developed For rough terrain areas. Legged robots can jump or step over obstacles whereas wheels need to somehow travel over it, or take a different path Wheels require a continuous path to travel whereas legs can step over isolated paths and move on. Legged robots can avoid undesirable footholds which cannot be avoided in a wheeled robot Legged robot helps us in exploring human and animal locomotion Once we move off from our modified habitat into rough, rocky, sandy, steep and undesired terrain, we understand that our brilliant invention of wheels turn out absolutely useless Lastly, the excitement of replicating a human or an animal and try to challenge nature 2 LITERATURE REVIEW Figure in the previous page shows the leg mechanism, using a Klann mechanism to imitate the spider insect leg.
Force transmission is very important for leg mechanisms, because of the point contact with the ground. The leg mechanism, with its body size shown in Figure mentioned in the previous page. It has six links and seven cylindrical joints.
Wheels are ideally suited for movement without vertical fluctuations of the body, and tires with inner rubber tubes absorb shock from a rugged road. On the other hand, biologically-inspired robotics learn mobile flexibility from the living creatures of multiple legs and their coordination.
Good examples of this are arthropods, like spiders and cockroach and the robots are conventionally designed with actuators placed in every joint. Therefore, in the design of disaster robots, which need to move on rubble and carry rescue devices, continuous tracks or crawlers are popular. Theo Jensen a Dutch kinetic artist who has attempted to create a bridge between art and engineering by focusing on biological nature, proposed a linkage mechanism to mimic the skeleton of animal legs.
This has a name Strandbeests. Which means Beach animal the following figure shows how it looks exactly Pic: from learningfromdogs. Each individual leg structure is placed side by side to form that structure. There are six links in Klann mechanism they are fixed frame, crank, upper rocker arm, lower rocker arm, and connecting arm main leg link.
Fig 3. The computer model is showing how the six-legged robot can be designed and how it can be simulated. Our project is going to simulate the computer model and perform analysis on the single leg of the walking robot based on Klann linkage by using FEM concept.
There are so many CAD tools to perform this analysis. By using one of the CAD tools the project is going to work on it. Each software has its own style of designing and analysis procedures. The project is completely based on those CAD tools. So we are going to choose the one which has more flexible to us in designing and Analysis. But unfortunately both design and Analysis is not easy with a single software.
But solid works also can do the analysis but the problem is accuracy. Fig 2. Here there are no changes done in the dimensions of any link of the leg mechanism. If any changes made in Connecting arm then the path traced by the point on main leg link changes. That is shown in the following figure 2. The path is little twisted when it is touching the ground so that the flexibility and stability of the leg are changed and it is not suitable for the design of walking robot.
Now the project is going to change the dimensions of the crank. It is similar to the first fig 1 but here the project cannot observe the motion of the main leg link. If we see the motion of the main leg link, there is a difference between the motion velocity. It enables designers to create a mathematically correct solid model of an object that can be associated with the properties of the materials used, the project can get a solid model that can be used to simulate and predict the behaviour of the part or model with finite element and other simulation software.
The same solid model can be used to manufacture the object and also contains the information necessary to inspect and assemble the product. The marketing organization can produce sales brochures and videos that introduce the product to potential customers.
And much easier to use. They are part modelling, Assembly modelling and Drafting. In part modelling there is a different kind of additional modules are there like surfacing, sheet metal, sketcher, mould tools, Weldments and office products.
Which is optional for choosing the dimension of the bot whether the bot is bigger in size or smaller. According to that, the project can change that dimensions of the Klann mechanism. So the project is not going to change that dimensions of Klann mechanism. The project considering the true dimensions for leg and based on that dimensions the project changing the dimensions of bot to avoid difficulties in designing of the entire walking robot. So the project is considering the length and height and width of the robot according to the length of the leg.
These dimensions are only considerations. Not fixed. The above model can be simulated how the walking robot can walk. But according to the above model the project can simulate only forward and backward direction only.
Because two legs of the robot are mounted on the single frame. But it is needed to each leg should be mounted on individual frames and those should have free DOF along the horizontal direction.
Then the robot can easily get turnings for the six-legged robot. But the power transmission for each individual leg in control gear ratio. This can be achieved by the sensors and actuators. Then the project can design a successful six-legged walking robot which can go anywhere like living creatures like crab and spider.
Actually, this kind of robots called as Mechanical spiders. This name was already given by the Klann in their official website.
But they are designing legged robots consisting of four legs. That could be more advantageous than six-legged because of less number of joints and links will result in less friction. In our there is only one motor is mounted on the frame. The project can also mount individual motors for the individual cam.
One motor for back three legs and a second motor for front three legs. But the motors should follow the same gear ratio. Otherwise, the project cannot get the walk for the robot. This will helps to take turnings when the two motors rotating in a reversed direction. And in the same direction will result in forwarding or backward moment.
Computer Aided Design and Analysis of the Walking Mechanism
3D Printed Walking Robot (Klann Linkage)