Rocker bogie mechanism pdf

In order to mimic the suspension capabilities of the rovers sent to Mars by NASA, our rover will incorporate the same rocker bogie suspension system utilized by the Mars rovers to traverse an extreme desert-like terrain. This suspension system, introduced with the original Mars Pathfinder project, is the same design preferred by NASA for nearly all the Mars rovers.

Rough Terrain Vehicle Using Rocker Bogie Mechanism

The main advantage of this type of suspension system is that the load on each wheel is nearly identical and thus allows an equal distribution of force regardless of wheel position.

Taking into consideration the harsh terrain found on Mars this type of suspension system provides a better alternative to that of the common 4-wheel drive soft suspensions found on most automobiles. For our project, since we are mainly building upon the design of previous semesters, we can utilize the things they did correctly and build upon things they may have overlooked.

The main design difference, as it pertains to the suspension system, is the addition of a differential gear box. Whereas previous semesters utilized a barely functioning differential bar, or no differential at all, this semester we decided to remove the bar entirely and replace it with a much more functional differential gear box.

This addition of a differential gear box will offset the wheel assemblies by about. Upon further research of rover suspension systems our group discovered a helpful blog on a website called Beatty Robotics. The website provides many helpful blogs describing the design and creation process for many custom Mars rovers and other robots. The particular blog post that helped us meet our needs pertained to a differential system used for a custom Spirit II Mars rover.

Feedback on the blog pertaining to the parts used lead us to the website McMaster-Carr where we were able to order the parts to assemble our own Differential. The wheel assemblies contain a total of 6 wheels with a symmetric build for both sides.

Each side contains 3 wheels which are connected to each other by two links. The main linkage called the rocker has two joints, one affixed to an axel forming the differential mechanism and the other connected to the remaining two wheels. This linkage from the rocker to the other linkage between the two wheels is known as a bogie hence the name rocker bogie.

To go over an obstacle, the front wheel is forced against the obstacle by the center and rear wheels.

rocker bogie mechanism pdf

The rotation of the front wheel then lifts the front of the vehicle up and over the obstacle. The middle wheel is then pressed and pulled against the obstacle by the rear and front wheels respectively until the wheel is lifted up and over the obstacle. Finally, the rear wheel is pulled over the obstacle by the front two wheels.

The differential is composed of three identical beveled gears situated degrees from each other at the center of the rover. Each gear is affixed to a 6-inch steel drive shaft that is mounted to the rover body by 2 mounted sleeve bearings.

One gear connected to the left, one gear connected to the right, and the last gear assembled onto the main platform. The two rods facing opposite of each other on the left and right of the robot help serve as axels for the wheel assemblies.

The axils are connected to the wheel assemblies by 2 parallel aluminum tubes that make up the rocker bogie suspension system. If one leg goes over an obstacle, an opposite force is applied to the other leg. So, if one leg goes up, the other leg goes down. This downward force onto the opposite leg helps the robot maintain traction in the leg assembly that is still on the ground. The way this works is when one side changes in pitch, say for instance one side begins climbing over an obstacle, this mechanism rotates the main body around the rocker joints by the average rotation angle of the two sides.The rocker-bogie suspension system has robust capabilities to deal with uneven terrain because of its distributing of the payload over its six wheels uniformly, while there is one major shortcoming to high-speed traversal over the planar terrain.

This paper proposes a new dynamic rocker-bogie suspension system with two modes of operation: it can expand the span of the rocker-bogie support polygon to increase travel rate when the terrain is planar; and it can switch to its original configuration to move by low speed when it is faced with rough terrain.

The analysis on dynamic stability margin and kinematical simulation on the two operating modes of rocker-bogie are employed to analyze and verify the rationality and effectiveness of the modification in the structure. All-terrain mobile robots are different from other ordinary mobile robots, because they consider the effect of unstructured terrain and its environment [ 1 ].

Therefore, these robots are designed to operate effectively on natural terrains that may be sloped, rough, and deformable [ 2 ] and are used in such fields as deep space exploration [ 34 ], safety and rescue [ 56 ], and military and civilian application [ 78 ].

In order to ensure that the task is successfully achieved, it is a key issue to design and optimize the suspension system of all-terrain mobile robots to improve its mobile performance. However, the rocker-bogie suspension system has still some shortcoming. First, the average speed of operation is very slow.

Second, it makes the rocker-bogie system not suitable for situations where high-speed traversal over hard-flat surfaces is needed to cover large areas in short periods of time. In pursuance of achieving a greater stability margin over high-speed traversal without losing the original configuration, a new dynamic rocker-bogie suspension system, with two modes of operation that can switch between original configuration and high-speed traversal configuration, is introduced in this paper.

For high-speed traversal mode of rocker-bogie suspension system, it can expand the span of the rocker-bogie support polygon to increase speed when moving on hard-flat terrain or uneven terrain with minor obstacles. On the other hand, it can automatically switch to its original configuration to move by low speed when it is faced with rough terrain and significant obstacles.

The remaining parts of this paper are organized as follows. In Section 2we propose modification in the structure of the rocker-bogie suspension system increasing the span of the support polygon.

In Section 3we analyze the stability margin of the structure modification by force-angle stability measure. The analysis and verification by the Adams simulation will be shown in Section 4. Finally, the conclusions are given in Section 5.

The rocker-bogie suspension system is a passive springless and symmetric mechanism. Each side of the rocker-bogie has a rocker and a bogie: the rocker is connected to the rear wheel, and the middle wheel and the front wheel are connected by the bogie.

The two sides of rocker-bogie are connected by the differential bar attached to the main body, which ensures that the six wheels are in contact with the ground all the time providing a stable platform for the scientific instruments and sensors, as shown in Figure 1. The rocker-bogie suspension system is good at dealing with obstacles and excellent traversability.

However, the rocker-bogie based robots must move at a very low average speed to ensure the stability of traveling [ 10 ]. In some situations, mobile robots mostly face slightly uneven terrain with rarely significant obstacles on it.

This is why we proposed a configuration modification, expanding the span of the rocker-bogie system support polygon to increase the traversability. Nevertheless, when it needs to deal with obstacles, it can switch to its original configuration without losing its native robust capability. The three-dimensional model of the original configuration and the proposed high-speed traversal configuration is introduced in Figure 2.

As Figure 2 shows, the original configuration can only rotate in a pitch axis located at the front part of the rocker.This time, we thought of taking their moving ability a bit further and make them capable of reaching new heights. Program it in PictoBlox — a versatile graphical programming software with advanced capabilities, and control with Dabble — our ingenious project-making and controller app — in your hands, you hold the key to it.

So, are you ready for taking your robot to the next level? Before we start making the Stair Climbing Robot, we need to understand its parts. Most of the body structure of the robot is made of MDF sheet whose design can be found here. The labels in the image below indicate the following use:. You can see the following image for making the entire nervous system.

The powerhouse in our case is none other than the Battery. As we know that the brain sends the signal to the body, similarly evive will send a signal to the robot. But what will be those signals? How will evive know what signal to send? To make the coding process simpler we are going to code in the graphical programming software called PictoBlox.

You can either write the following code by dragging and dropping a few blocks or you can directly download the code given here. Stair climbing robot works on the concept of the rocker-bogie mechanism. The robot can climb onto any obstacles stairs, bumps, etc. It can move along any surface be it sand, rocks, concrete, or grass as it has suspension arrangments. The front wheel of the robot hits the obstacle real hard and as the friction of the wheels is more, it lets the robot to climb the obstacle.

Also, we are going to control it using our Smartphone. Dabble lets you connect your smartphone to evive. The buttons of Gamepad are used for the following function:. With this, your Smartphone-controlled stair-climbing robot is ready! Go ahead and reach new heights together! Connect the motors parallelly of the sides on the breadboard.To browse Academia.

Skip to main content. Log In Sign Up. Iaeme Iaeme. Most of the rover designs have been developed for Mars and Moon surface in order to understand the geological history of the soil and rocks. Several mechanisms have been suggested in recent years for suspensions of rovers on rough terrain. Our design of eight wheeled rocker-bogie suspension system has advantage of linear bogie motion which protects the whole system from getting rollover during high speed operations. This improvement increases the reliability of structure on rough terrain and also enables its higher speed exploration with same obstacle height capacity as diameter of wheel.

In this paper we simulate rover to find slip and its deviation from desired path and express the complete process of importing SolidWorks file into MATLAB. We use eight wheeled rocker bogie suspension mechanism for our simulation. For this purpose we made component in SolidWorks. In SolidWorks each and every parts are analyzed and simulated using SimulationXpress. This slip reduces rovers speed and leads to power loss.

Power loss reduces mission time by discharging batteries. Since we cannot control the availability of solar energy, as this is only power source on the other planet, we have to control power loss.

We can extend mission time by controlling slip and reducing rover sinking into loose soil which gives more time to our rover for exploration.

The suspension mechanism of the rover was designed using a rocker-bogie mechanism. They conduct experiments to find an optimal design of the kinematic variables of the rocker-bogie mechanism for stable stair climbing. Figure 2. It should be noted that only CAD assembaly files can be converted into Simulink model.

The resulting SimMechanics model can be rearranged and add background colours for easier understanding. As there is no one- to-one correspondence between SolidWorks mates and SimMechanics joints, the conversion is not always possible, or it does not translate as intended. Ellipse major axis is 3. Angle subtended between major axis and horizontal is We are generating total points in our simulation and running it for 10 seconds.

We are tried to figure out slip behaviour for our wheel design.As with any suspension system, the tilt stability is limited by the height of the center of gravity.

Systems using springs tend to tip more easily as the loaded side yields. The Rocker-Bogie system has been the suspension arrangement used in the Mars rovers. These rockers are connected to each other and the vehicle chassis through a differential.

Relative to the chassis, when one rocker goes up, the other goes down. The chassis maintains the average pitch angle of both rockers. One end of a rocker is fitted with a drive wheel and the other end is pivoted to a bogie.

Rocker-Bogie Mechanism

Robots using rocker bogie mechanism make use of a suspension mechanism that consists of several rigid elements connected through joints of a certain number of degrees of freedom DoF resulting in a structure that has one system DoF.

This enables them to move along uneven terrain without losing contact with the ground. Following table represents 3 such possible joints:. The suspension has 6 wheels with symmetric structure for both sides. Each side has 3 wheels which are connected to each other with two links. The main linkage called rocker has 2 joints. Another alternative to move on a harsh environment is to have big wheels.

If a rover has large wheels compared to obstacles, it can easily operate over most of the Martian rocky surface. Inflatable rover has 3 wheels which are driven by motors. Robot could be able to travel approximately 30 km per hour on Mars surface by its watt power. Below mentioned is the best dimension ratio for the Rocker Bogie mechanism to be the most effective in its use.

Rough Terrain Vehicle Using Rocker Bogie Mechanism

Types Of Joints Robots using rocker bogie mechanism make use of a suspension mechanism that consists of several rigid elements connected through joints of a certain number of degrees of freedom DoF resulting in a structure that has one system DoF. Following table represents 3 such possible joints: The suspension has 6 wheels with symmetric structure for both sides. Advantages: Load on each wheel is nearly identical Has no axles or springs which helps to maintain equal traction force on all the wheels.

Can climb over blocks twice the height of the wheel while keeping all 6 wheels on the ground Each wheel can individually lift almost the entire mass. Effective Mechanism Below mentioned is the best dimension ratio for the Rocker Bogie mechanism to be the most effective in its use.The two front and two rear wheels also have individual steering motors one each.

This steering capability allows the vehicle to turn in place, a full degrees. The four-wheel steering also allows the rover to swerve and curve, making arching turns. The design of the suspension system for the wheels is based on heritage from the "rocker-bogie" system on the Pathfinder and Mars Exploration Rover missions. The suspension system is how the wheels are connected to and interact with the rover body.

The term "bogie" comes from old railroad systems. A bogie is a train undercarriage with six wheels that can swivel to curve along a track. The term "rocker" comes from the design of the differential, which keeps the rover body balanced, enabling it to "rock" up or down depending on the various positions of the multiple wheels. Of most importance when creating a suspension system is how to prevent the rover from suddenly and dramatically changing positions while cruising over rocky terrain.

If one side of the rover were to travel over a rock, the rover body would go out of balance without a "differential" or "rocker," which helps balance the angle the rover is in at any given time. When one side of the rover goes up, the differential or rocker in the rover suspension system automatically makes the other side go down to even out the weight load on the six wheels.

This system causes the rover body to go through only half of the range of motion that the "legs" and wheels could potentially experience without a "rocker-bogie" suspension system. The rover is designed to withstand a tilt of 45 degrees in any direction without overturning. However, the rover is programmed through its "fault protection limits" in its hazard avoidance software to avoid exceeding tilts of 30 degrees during its traverses.

The rover rocker-bogie design allows the rover to go over obstacles such as rocks or through holes that are more than a wheel diameter 50 centimeters or about 20 inches in size. Each wheel also has cleats, providing grip for climbing in soft sand and scrambling over rocks.

The rover has a top speed on flat hard ground of 4 centimeters per second a little over 1. Mars Curiosity Rover. One of the black, cleated wheels of the Mars Science Laboratory rover. Made of aluminum, with cleats for traction and curved titanium springs for springy support.

One full turn of a wheel with no slippage is about 62 inches centimeters of driving.To browse Academia. Skip to main content. Log In Sign Up. IOSR Journals. Nagappan3, P. Corresponding Author: G. Shanmugasundar Abstract: Rocker bogie finds a vital role in determining the scientific analysis of objectives separated by many distance apart. The mobility design at present is quite a bit complex with many legs or wheels.

Rocker-bogie

The wheeled rover which is capable of driving over the rough terrain provided with high degree of mobility suspension system. The drive provided by the rocker bogie is simple and it mainly operated by the means of two motors.

The motors are kept inside in order to make it more reliable and efficient. In overcoming the bumps in the natural terrain the wheels are operated simultaneously.

rocker bogie mechanism pdf

By implementing this mechanism the vehicle can come through any obstacles it faces during the travel in the terrain. We have tested it by conducting a series of mobility experiments on agricultureland,rough roads,inclined,stairsandobstaclessurfaces and concluded that it is possible to implement. This project mainly focuses how the mechanism finds its place in the wheel chair.

rocker bogie mechanism pdf

Keywords-Wheel Chair, Rocker Bogie Mechanism Date of Submission: Date of acceptance: I. As the time goes on we must remember of deprived people. We need to find a way to support such a individuals with deprived legs,hands or other parts of the body.

They were too dependent on others for everything,so we need to understand their feelings and provide a way to carry out their life.

It is difficult for them to migrate from one place to other. The mobility of an individual is being restricted. The small scale manufacturers were keen on their efforts to develop the cycle that suits them but it is not in the case of other transportation facilities.

The tricycle invention provided them with increased mobility and independence. So we had an idea of inventing a wheel chair with rocker bogie mechanism. It consists of motor,battery,links and wheels. The suspension design used in this mechanism offers vehicle stability. The rocker bogie suspension finds its first application in Mars Exploration Rover project.