STATEMENT OF INVENTION:
The present investigation discloses the fabrication of a bipedal robot to mimic the human walking pattern. This robot is designed for navigation and obstacle avoidance while walking.
BACKGROUND OF INVENTION: Field of Invention
The present invention relates to an autonomous biped robot having 8 degrees of freedom.
Background of invention
From earlier times significant research has been carried out for developing sustainable technologies to conquer rugged and impassable terrain which is quite out of the domain of wheeled locomotion systems. On the other hand researchers have realized the increasing importance of human assist machines which have human like morphology and are able to operate in cluttered environments. Bipeds offer a huge flexibility in motion in challenging environments where their wheeled counterparts fail to move. Development of bipedal and humanoid robots has become crucial in all fields of human work domain.
This invention describes a bipedal robot having 4 degrees of freedom for each leg. For each. degree of freedom a servo motor is attached as actuator that enables the robot to walk through the specified terrain. While walking, a stable gait pattern as well as balancing of the upright, moving part is achieved through the data acquisition from an accelerometer. Also two ultrasonic sensors are incorporated at the top of the biped for avoiding the static and dynamic obstacles as well. An optimal path planning is addressed in various cluttered environments by implementing some walking algorithms through the ARDUINO board.

Prior Art
• U.S. Patent No. 6640160 B2 to inventor Takahashi et al. discloses a biped ambulatory robot. The robot has an electrical storage device for the power supply of robot operation. It reduces the load on the knee joints of the legs and makes the robot enable to maintain the stability of robot posture.
• U.S. Patent No. 8565921 B2 to inventor Doi discloses a method to determine grounding timing for a biped walking robot. Here they concentrated on the grounding time and Zero Moment Point (ZMP) position of the legs of biped robot for a stable walking.
• Published patent application 2004/0030455 Al to inventor Hirai et al. discloses a technique to determine the. size especially height of a bipedal robot according to the group of objects with which the robot will work. Again it enables a stable walking like a human being, staircase climbing, standing with one leg and adapting various types of environments for smooth operation.
• Published patent application US 2004/0030447 Al to inventor Takahashi discloses a humanoid robot i.e. a biped locomotion robot. The biped is designed here to work in difficult environments like fire scene or chemically hazardous area instead of a human being. Also here, the feet are rising, and foot grounding movement of the robot is described.
• Published patent application US 2004/0193.3,23 Al to inventor Higaki et al. discloses a control system for a biped robot for the detection of static or dynamic objects around it by the help of cameras. A lot of cameras are mounted on the robot that captures stereoscopic images around it with the help of image analyzer and moving object detector to avoid obstacles and move forward.
• U.S. Patent No. 8447429 B2 to inventor Chang et al. discloses an apparatus for balancing and control of damping in the body of a biped humanoid robot. They concentrated on the stabilization and reduction of structural vibration of the robot body while walking, and endeavour a stable and balanced walking by compensating the trajectories of the Center of Mass (COM) and Zero Moment Point (ZMP).
• Published patent application US 2013/0211586 Al to inventor Lee et al. discloses a novel method to track the control of a biped robot. One control apparatus is invented

which is more reliable to maintain the balancing of a biped robot by posing the target information in any critical conditions along with any physical disturbances.
• Published patent application US 2009/0114460 Al to inventor Amino et al. discloses a bipedal system with the wheel and also with two legs like a human. The robot is designed so that for the leveled surface it uses wheel for movement where as for unlevelled ground it walks like a human with its two legs by exchanging quickly from wheel mechanism to bipedalism.
• U.S. Patent No. 6564888 Bl to inventor Gomi et al. discloses a bipedal mobile robot. The linkages (legs) are so designed that it balances itself taking care of gravity axis and absorb and alleviate footfall impact, offering a high degree of freedom in gait pattern and giving a stable walking.
• Published patent application US 2003/0017779 Al to inventor Sakai discloses a biped toy that can walk just like a human being. Here they concentrated on the walking of toy biped by lifting of the right leg to move the center of gravity while left leg will take a forward step and vice versa just to mimic the human being.
• U.S. Patent No. 6992456 B2 to inventor Furuta et al. discloses a two-legged biped walking controller that has a good stability with consumption of less energy. A walking controller is designed which has taken a gait pattern of legs and stabilize the walking with a good power management.
• Published patent application US 2011/0272199 Al to inventor Skaff discloses a novel method for actuation of a bipedal robot mechanism. The Legs are rotatably coupled to the chassis at both the sides and as per the method both of the legs are positioned at 180 degrees about to each other for balancing. To balance the walking posture large feet are designed as those have large contact areas with the walking surface.
• Published patent application EP 2208583 Al to inventor Furuta et al. discloses a mobile walking mechanism for a bipedal system. Avoiding the conventional methods i.e. just following the designed gate pattern here concentration is given to the unexpected road with uneven surfaces, taking a new gate pattern and stabilizes the walking of the biped.

OBJECT OF THE INVENTION:
Primary object of the invention is to provide a bipedal robot which has the ability to walk autonomously mimicking human motion.
Another object of the invention is to provide a reprogrammable platform for studying dynamics of human walking.
Yet another object of the invention is to provide models for obstacle avoidance and navigation using a bipedal system.
Still another object of the invention is to provide a miniaturization of a bipedal robot that able to carry objects in form of payload.
SUMMARY OF INVENTION:
The invention relates to fabrication of a biped robot that can be used for studying bipedal locomotion and all the related issues in controlling the higher degrees of freedom. As a simple task, first various bipedal walking models have been compared with respect to the standard human biped model and all other existing models. Although humans have more than 12 degrees of freedom below the torso region, for simplification in analysis the biped considered here has 8 degrees of freedom. For both the legs four degrees of freedom are there. At the ankle and in the knee joint there is one DOF to get roll and pitch orientation respectively and at the hip joint two DOFs are there to get roll and pitch orientations. It can navigate avoiding all obstacles in cluttered environment using its sensory data. Again its small size enables it to be used for inspection purpose in many hazardous locations which is merely unreachable for human beings.
In the current invention there are thirteen parts and are articulated uniquely to get a stable structure. For both the legs part 1 and part2 are joined by 2 pairs of nut and bolts. Part2 and part3 are joined at two sides. One side is joined by a servo motor and other side is joined through a bearing arrangement. Part3 and part4 are joined by 4 pairs of nuts and bolts. Part4-part5 and part5-part6 are joined by servo motors. Part6 of both the legs are connected to the top part of biped through two servomotors.
In the current invention 'S' shaped parts are uniquely designed (This is not reported in the previous existing patents) for giving a stabilized structure.

DETAILED DESCRD?TION OF INDIVIDUAL COMPONENTS:
1. Actuators: At all joints HiTec HS-985MG servo motors have been used to give a motion
to the Biped Robot. These motors are chosen after studying their torque capacity and speed
of control, as required in the biped. These motors impart a total of 8 degrees of freedom to
the robot. One is installed in the toe section for roll, one in the knee section for pitch, and
two in the hip for yaw and pitch.
Specifications of HITEC HS-985MG Servo motor
Motor Type Coreless
Bearing Type Dual Ball Bearing
Speed (4.8 Volt/6Volt) 0.16 Sec/600 / 0.13 Sec/600
Torque (4.8 Volt/6Volt) 9.60 kg-cm /l 2.40 kg-cm
Size Length 39.88 mm, Width 19.81 mm,
Height 36.83 mm
Weight 61.8 grams
2. Control Module: Arduino Mega 2560 is used for control of the servo motors used in the biped robot. It is also used to regulate the position of the robot in accordance to the ultrasonic range sensors connected to the Arduino. Thus the Arduino is effectively the brain of the biped. It is mounted in a rectangular section on top of the two legs.
3. Biped body parts: To frame the body of the biped robot, 1.5 mm thick aluminium sheet is taken and then is machined as per the design. Then to get the required degree of freedom those are bolted through servos at all joints.
4. Power Supply: For the motion of the biped 5 volts power supply has been supplied by a SMPS to all the servos as well as to the Arduino board.
5. Bearing Arrangement: At the bottom of the legs i.e. at the ankle joint.one roller bearing has been used, as here all the loads on the biped are acting.
6. Accelerometer (ADXL335-V2.0): At the top part of the biped one 3-axis sensing accelerometer is placed to know the acceleration in x y and z directions which helps to regulate the position of centre of gravity for balancing the robot in walking position.
7. Ultrasonic Sensors (HCSR04): At the top part of the biped two ultrasonic sensors are fitted to detect the obstacles and avoid the same during navigation.
Specifications of Ultrasonic sensor
Power Supply: 5V DC .

CLAIMS
We claim
1. In this invention a Bipedal Robot is invented, consisting of eight dc servo motors at various joints to have eight degrees of freedom (DOF) weighing 1.4kg and having a height of 34 centimeters, to accurately move and mimic the human walk behavior.
2. According to claim 1, the robot has 12 links, each leg has 6 links, and the two legs are joined by a single top part.
3. According to claim 1, for every leg four degrees of freedom are there to achive stable gait trajectory; at the ankle and in the knee joint there is one DOF to get roll and pitch orientation respectively and at the hip joint two DOFs are there to get roll and pitch orientations.
4. According to claim 1, for both the legs part 1 and part 2 are joined by two pairs of nuts and bolts, part 2 and part 3 are joined at two sides. One side is joined by a servo motor and other side is joined through a bearing arrangement, part 3 and part 4 are joined by four pairs of nuts and bolts. Part 4 and part 5 are joined by a servo motor. Part 5 and part 6 are joined by a servo motor. Part 6 of both the legs are connected to the top part of biped through two servomotors.
5. According to claim 1, the 'S' shaped structure of the leg gives a unique overall rigidity towards bending.
6. According to claim 1, an Arduino-based program has been written and implemented for achieving the smooth walking and control of biped robot while avoiding obstacles around it with sensory data.
7. According to claim 1, two ultrasonic sensors are interfaced to know the position of obstacles in front of the robot for hassle free movement.
8. According to claim 1, one accelerometer is installed to know accelerations in x, y and z directions which help to regulate the position of centre of gravity for balancing the robot in walking condition.