Chapter human walking and building human like robot
Introduction to Self balancing and stair climbing robot
Due to technological advance of robotic applications in human life it is necessary to overcome the problems faced in robot’s walking, changing direction, crossing obstacle, and climbing stairs.
The advances in automation and robotics have garnished the way for development of human like robots. Robotics community has been involved in studying the human walking and building human like robot to achieve most of the complex tasks. Humanoid robots have been built to adapt itself into environment of humans that can avoid and cross over obstacles and climb stairs.
Stair climbing is one of the most attractive performances of a robot in legged and wheeled. Developments have been made on various kinds of stair climbers, considering how to make its climbing ability higher and its mechanical complexity reasonable and practical. Reducing body weight and energy consumption is the main thing on which researchers are working.
Adjustable stair climbing robot is one of the most attractive performances of robot in legged and wheeled.
Researchers designed Algorithms to find the goal directed navigation strategies for humanoid robot. Biped robots are suitable for indoor environments including the navigation on rough terrain and uneven surfaces. Passing over the obstacles is special feature of humanoid robot unlike wheeled robot. 1
Biped robots can walk on uneven slopes and surfaces unlike vehicular robots. Biped robots are optimum choice for jobs that are hazardous to people such as defusing bombs, rescue operations, finding survivors in unstable ruins, and exploring mines and shipwrecks. The human like robots helps to saves labor and time with minimal amount of loss in hazardous situations.
A humanoid robot is an autonomous robot, because it can adapt to changes its environment or itself and continue to reach its goal
In our design of developing humanoid legs, we are focused on the design of a self-balancing and stair climbing robot
It can also avoid obstacles, not by changing its directions only but by crossing over it.
The robotic legs have 8 DOF (degree of freedom); four for each leg. Two degree of freedom (forward/backward, up/down) for knee joints, and two for ankle joints
First step of this project involves the designing of basic structure of robotic legs, and itself balancing. This is achieved by the use of balancing algorithms and level sensors. Balancing algorithms and level sensors will work together and make the model stable and balance. They will continuously watch over so many things in order to achieve balance and stability of robotic legs, i.e. how the vertical movement will support the body, changing the torque of moving legs, and adjusting that torque, sensory feedback. Other important points for achieving the stability of robotic legs are COG for static walking and ZMP for dynamic walking. For balancing purpose walking sequence, walking sequence control, and walking sequence phases (single phase, double phase) should be observed carefully
Stair climbing of robotic legs is achieved by the use of Ultrasonic and level sensors, that detect the obstacles, send the signals to Arduino which drives the servo motor accordingly.
Self-balancing and stair climbing robot is two legged Arduino controlled actuated robot with 8 Degrees of freedom. Signals from level sensors and Ultrasonic Sensors will work as an input to the Arduino. Arduino will program those signals and will provide output signals to the servo motors, and it will drives servo motors according to the input signals. Servo motors will let the robotic legs move. Ultrasonic sensors and level sensors are used for climbing and self-balancing purpose.
The Aim of Biped robot is to serve as companions and assistants for humans in daily life and as ultimate helpers in man-made and natural disasters.
It can provide comfort and safety to humans. The idea behind application of biped robots is self-balancing and stair climbing. The main practical issues in developing such a robot are the speed and stability of the robot while climbing stairs.
In development of Stair climbing two legged Arduino controlled biped robot, firstly, we have to deal with self-balancing. It will also have the capability to avoid obstacles by changing its direction or crossing over the obstacle.
For Humans, balancing for a Robot with two legs is one of the most difficult tasks, a task that consumes considerable energy resources and computing power to achieve self-balancing and stair climbing. Therefore, we need servo motors having 40kgcm of torque.
Early biped robots use the technique of static walking which has a very low walking speed. The step time was over 10 s per step and the balance control strategy was performed through the use of COG (Center of Gravity). The projected point of COG onto the ground always falls within the supporting polygon that is made by two feet. During the static walking, the robot can stop itself from walking any time without falling down. The disadvantage of static walking is its slow motion and that it is wide for shifting the Center of Gravity.
Thus, researchers began to focus on dynamic walking of biped robots. It is fast walking with a speed of less than 1 sec per step. If the dynamic balance can be maintained, dynamic walking is smoother and more active even when using small body motions. However, if the inertial forces generated from the acceleration of the robot body are not suitably controlled, a biped robot easily falls down. In addition, during dynamic walking, a biped robot may fall down from disturbances and cannot stop the walking motion suddenly. Hence, the notion of ZMP (Zero Moment Point) was introduced in order to control inertial forces 1
1.3 Aims & Objectives:
There were many issues being faced by vehicular robots, i.e. they were too heavy, had very complex structure, used high power sources and much more. The objectives behind designing this model were to solve or at least reduce these problems.
The main objective of this project is to develop human like robotic legs with the capabilities of self-balancing, stair climbing and avoiding obstacle
We are proposing a robot that looks a lot like the human legs that can balance itself, according to the height of step
Robotic legs must be capable of stepping up and down staircases, and other obstacles, where a sufficient large flat surface can support the robot’s feet
The other objectives of this system are:
Ø Able to move around on normal flat surface
Ø Able to walk on a known slope
Ø Balance control
Ø Ability to detect the level of steps
Ø Has an ability to step over and cross over steps
Ø Stair recognition
Ø Doesn’t lose balance and stability while walking, crossing an obstacle, changing the direction and climbing the stairs
This model has major applications such as military robots, or security robots in urban environments, along with this, other applications are:
Ø Personal assistance
Ø Security and hazardous environments
Ø Rescue operations and military activities
Ø Robot Competitions
Ø Access and scan areas human cannot get go
Ø Building and home management
Ø Plant Management
Ø Industrial Vehicular operation
Ø Collaborative outdoor work
Ø Care support system
Ø Agricultural work
Ø Disaster mitigation and as well as for urban search where robot should be able to deal with rough terrain and even to climb stairs.