STATEMENT OF INVENTION:
The present invention discloses an automated four-wheeled intelligent stair climbing mobile robot. This robot can climb a stair whose inclination is angle up to 39° (degree) and also capable of navigating in all types of terrains with the top speed of 0.18m/sec. This stair climbing mobile robot is suitable for the transport of goods, materials, and devices in the hospital, industry, military, space, etc. The specially designed mechanical structure (chassis) and the four wheels are provided to navigate a robot on the different staircases as well as flat surfaces. Compared with the prior arts, the robot has a simple mechanical structure (chassis), which can be made quickly.
BACKGROUND OF INVENTION: Field of invention
This invention is on development of automated four-wheeled intelligent mobile robot that can climb or descend stair or similar obstacles and navigate in all types of terrains. The stair climbing mobile robot can be used for the transport of goods, materials, and devices in the hospital, industry, military, space, etc.
Background of invention
The applications of the autonomous robot in industries, space, defense, transportation, and other social sectors are growing day by day. The mobile robot performs many tasks such as rescue operation, patrolling, disaster relief and planetary exploration, etc. Therefore, an intelligent mobile robot is required that could travel on all types of terrains. The present invention focuses on the design and development of the low cost, light weight, simple mechanical structure, and low power consumption automated four-wheeled intelligent mobile robot, which is capable of climbing or descending stair. The mobile robot comprising a specially designed gripper wheels, which will grip the sharp corner of the staircase to minimize the friction. Prior Art
1. U.S. Pat. No. 20080296853A1 to inventors Langford et al. discloses the remote controlled mobile robot and a mechanism that assists a mobile robot in climbing stairs.
2. U.S. Pat. No. 4993912A to inventors King et al. discloses the wheel over wheel mechanism based remote controlled robot, which is capable of climbing the stairs. The motor is used to drive the each pair of the wheels during stair climbing in the same direction at a predetermined rotational velocity.

3. Smart stair chairs can support the patients in the many situations. U.S. Pat. No. 8640798B2 to inventors Walkingshaw et al. discloses the lightweight motorized stair chairs. The motor and frame can lift the patient to climb or descend the stair.
4. U.S. Pat. No. 8360178B2 to inventors Goldenberg et al. presents the mobile robot that includes a chassis, a pair of the drive system, a manipulator arm with a turret, and a linkage mechanism with a dual function. The advantage of the present invention is that, it can lift its front pulleys or wheels forward and upward to ascend and descend stairs.
5. U.S. Pat. No. 4932831A to inventors White et al. discloses the remotely controlled all-terrain mobile robot. This remotely controlled robot has a main chassis with rotatable tracks, which supports the central body of the robot during movement on an uneven terrain.
6. U.S. Pat. No. 4709265A to inventors Silverman et al. presents the radio remote controlled surveillance mobile robot. The robot has a unique size and shape, which controls the robot during navigation from the standard doorways, standard stairways, narrow passages, and inclined surfaces.
7. U.S. Pat. No. 20130231814A1 to inventors Sarokhan et al. discloses the electrically-powered stair-climbing wheeled robotic surveillance vehicle.

8. CN (Chinese) Pat. No. CN104699011A to inventors Yang discloses the wheel-legged stair-climbing robot control system. The proposed control system is comprising of host computer, display module, data transmission interface, keyboard input module, ARM controller, torque sensor, DC motors, motor control unit and the power module.
9. CN (Chinese) Pat. No. CN201525026U to inventors Kai et al. presents the modern disaster relief mobile robot that has a hexagonal body module, four wheels and five degrees of freedom robotic arm. The servo motor operates the robotic arm, and the wheel modules of the robot are run by the electric motors.
10. CN (Chinese) Pat. No. CN201760877U to inventors Light et al. discloses the deformable robot travelling mechanism suitable for all landforms. It is comprising of chassis, four-wheel mechanism and an overturning mechanism. The robot can climb the stair and across the ditch.

OBJECT OF THE INVENTION:
The primary objective of this present invention is to invent an automated four-wheeled intelligent mobile robot, which can climb or descend stair or similar obstacles and also navigate in all types of terrains. Furthermore, the developed intelligent stair climbing mobile robot may be utilized to carry or transport the loads up or down the staircase and to navigate in uneven terrain.
SUMMARY OF INVENTION:
In the present invention, we have introduced an automated four-wheeled intelligent stair climbing mobile robot, which has a simple mechanical structure (chassis), and it could climb different sizes of the staircase. The specially designed mechanical structure (chassis) and the four wheels are provided to navigate a robot on the staircase and the rough surfaces with a top speed of 0.18m/sec. The robot includes the Arduino MEGA microcontroller; four heavy duty side shaft DC geared motors, two motor controllers, two sharp infrared range sensors, four rechargeable batteries and the USB connection serial port. The motion and orientation of the automated robot are controlled by independent four DC geared motors. These motors are connected to the motor driver, and the driver pins are connected to the Arduino MEGA microcontroller. The microcontroller sends the command to the motor driver according to sensor data. Two sharp infrared range sensors are attached in the front side of the stair climbing mobile robot to read the big obstacles.
The efficiency and effectiveness of the present invention have been examined through the number of runs in the different sizes of the staircase. The robot has a low cost and simple mechanical structure (chassis), and it can be used for academic research purpose. The novelties of the present invention are as follows: (a) It can climb the staircase autonomously; (b) It can carry a load of 5kg during stair climbing; (c) It can navigate in uneven terrains; and (d) It has a unique type of wheel, which helps the robot to negotiate obstacles, stairs, and rough surfaces.
DETAILED DESCRIPTION:
The objective of developing this automated four-wheeled intelligent stair climbing mobile robot is for transporting of goods, materials, and devices weighing between 5-10kgs. The robot has a simple mechanical structure (chassis), which provides a better ability to climb the staircase with the minimum friction. The rocking frame works as suspension system when the robot travels in the uneven and rocky terrain. The model of four-wheeled intelligent stair climbing differentially steer controlled mobile robot is shown in Figures 1-5. The motion and

orientation are controlled by independent four heavy duty DC geared motors, which provide the necessary torque required during working of the robot. The direction control of the mobile robot is achieved by the differential steered control (motor speed) of all wheels. Four separate DC motors are used to drive each front wheel to facilitate turns (clockwise and anti¬clockwise), backward, and forward movements. 12Volt DC motors are attached to the DC motor driver and the each driver's direction and velocity control pins are connected to the Arduino MEGA microcontroller to drive each motor to facilitate turn left and right, backward and forward movements. The motor velocity is regulated by the voltage control signal. The intelligent stair climbing mobile robot is equipped with two sharp infrared range sensors, which read the obstacles from 20cm to 150cm approximately. The control parts specifications of the proposed intelligent stair climbing mobile robot are given below.



Major dimensions of the stair climbing mobile robot:
Length 33cm to 57cm (adjustable)
Width 40cm
Height 18.5cm
Wheel Diameter (inner) 26.5cm
Wheel Diameter (outer) 34.5cm
Width of Wheel 5cm
Track Width 54cm
Ground Clearance 13.5cm
DRAWINGS:
Brief Description of the Drawings:
The Figure 1-5 illustrates the various views of the intelligent stair climbing mobile robot.
Figure 1 shows the isometric view of the stair climbing mobile robot.
Figure 2 show the top view of the stair climbing mobile robot.
Figure 3 shows the side view of the stair climbing mobile robot.
Figure 4 shows the front view of the stair climbing mobile robot.
Figure 5 shows the rear view of the stair climbing mobile robot.

EXAMPLE 1
The stair climbing mobile robot may be used to climb or descend a different size staircase, whose tread and riser lengths are 30cm × 15cm, 38cm × 16cm, 27cm × 17cm and 24cm × 19cm and the corresponding slope angles are 26.56°, 22.83°, 32.2° and 38.37°, respectively.
EXAMPLE 2
The prototype stair climbing mobile robot crosses the obstacle (rocks) up to 25cm height.
EXAMPLE 3
The speed of the mobile robot on the flat ground is 0.18m/sec. The speeds of the mobile robot on different staircases are 0.12m/sec (30cm × 15cm), 0.145m/sec (38cm × 16cm), 0.956m/sec (27cm × 17cm), and 0.067m/sec (24cm× 19cm). The limitation for the proposed stair climbing mobile robot is that, it could climb 39° inclination staircase (maximum).
EXAMPLE 4
The robot achieves a maximum speed of 0.18m/sec during forward and backward motion and 0.12m/sec during clockwise and anticlockwise movements, respectively.
EXAMPLE 5
The gripper wheels are used to grip the sharp corner of the staircase during climbing the staircases.
EXAMPLE 6
The rocking frame works as a suspension system when the mobile robot travels over uneven or rough terrain.
EXAMPLE 7
All the four wheels can be adjusted from 33cm to 57cm using the central shaft of the chassis according to unevenness of the staircase and terrain.

CLAIMS:
We claim:
1. In this invention, a unique stair climbing mobile robot has been invented to climb the staircase and negotiate with obstacles in rough terrains.
2. According to the claim 1, special wheels have been designed to help the robot to climb the staircase and navigate in rough and rocky terrains.
3. According to the claim 1, a unique structure has been developed, which can negotiate different terrains.
4. According to the claim 1, two sharp infrared range sensors are incorporated in the stair climbing mobile robot to recognize the obstacles.
5. According to the claim 1, all the four wheels can be adjusted from 33cm to 57cm by using the central shaft of the chassis according to the requirements.
6. According to the claim 1, the robot is made in such a way that all the wheels get power during driving, which helps the robot to navigate in uneven terrain.
7. According to the claim 1, the robot can negotiate staircases and obstacles with a payload of 5kg.