GRD Journals | Global Research and Development Journal for Engineering | National Conference on Emerging Research Trend in Electrical and Electronics Engineering (ERTEE-2018) | March 2018
e-ISSN: 2455-5703
Self Balancing Vehicle 1Aishwarya
P 2Arathy K Rajeev 3Athul Gopi 4Edwin Joy 1,2,3,4 UG Student 1,2,3,4 Sahrdaya College and Engineering and Technology, Kodakara Abstract This paper gives the idea about stability issue that mobile robot facing and a stable balancing robot that balance itself on a pair of wheels. To found out a solution for this issue ;we have designed a self-balancing robot based on the principle of Inverted pendulum, which is a two wheel vehicle which balances itself up in the vertical position with reference to the ground. It consist both hardware and software implementation. The mechanical model is based on the state space design of the cart, pendulum system. A Segwaytype vehicle is a classic inverted pendulum control problem that is solvable in two degrees of freedom for the simplest models. The vehicle attempts to correct for an induced lean angle by moving forward or backward, and the goal is to return itself to vertical. Or at least not fall over. Keyword- Inertial Measurement Unit (IMU), Digital Motion Processor™ (DMP), Analog-to-Digital Converters (ADCs) __________________________________________________________________________________________________
I. INTRODUCTION In today’s scenario, Robots are inevitable in mass production industries compact robotic structure, that is more efficient and have even faster processing with wide range of applications from home based appliances to industrial CNC machines and from warcrafts to intelligent surveillance robots. Due to their agility and efficient performance as cannot be imagined a few decades earlier. Modern era of robotics comprises of more Robots have been widely used in automobile industries by the end of late 20th century for precise cutting, welding, placing and carrying purposes. Robotics has achieved its greatest success to date in the world of industrial manufacturing. Robot arms, or manipulators, comprise a 2 billion dollar industry. Bolted at its shoulder to a specific position in the assembly line, the robot arm can move with great speed and accuracy to perform repetitive tasks such as spot welding and painting. In the electronics industry, manipulators place surface-mounted components with superhuman precision, making the portable telephone and laptop computer possible. Yet, for all of their successes, these commercial robots suffer from a fundamental disadvantage: lack of mobility. A fixed manipulator has a limited range of motion that depends on the location where it is bolted down. In contrast, a mobile robot would be able to travel throughout the manufacturing plant, flexibly applying its talent. Wherever it is most effective. Conducting initial review research is very critical in understanding self balancing platform control techniques. The review of research about related literature conducted in this project summarizes some of topics related to the 21 techniques used for the balancing of platform based on Dc motor position. Comparisons between the present project and the related topics of existing information will also be discussed. The methodologies and the techniques used by other researchers around the globe on the balancing platform topic will also be reviewed. The following are the research works done by various researchers around the world.
II. PRINCIPLE OF OPERATION This paper is based upon the one of the fundamental problems a mobile robot experiences: Self-balancing. The robot has to be based upon such an electromechanical structure that balances itself onto a pair of wheels while standing tall. If the platform itself is not balanced, which means it keeps falling-off away from the vertical axis, then a gyro chip is needed to provide the angular position of the robot base and input into the controller, which is then programmed in a balancing algorithm. So we have to measure the angle of inclination (Roll) of the vehicle and also we have to control the motors for going forward or backward to make that angle 0, maintaining a vertical position. It will be prevented from falling by giving acceleration to the wheels according to its inclination from the vertical. If the bot gets tilts by an angle, than in the frame of the wheels the centre of mass of the bot will experience a pseudo force which will apply a torque opposite to the direction of the tilt.
III. DESIGN AND DEVELOPMENT The working of the project is as follows: It consist of two geared motors and their controlling motor driver, gyroscope and a programming device, here we are using Arduino Uno board. The vehicle starts functioning when an object is placed over it. The vibrations caused by the balancing of the object is sensed by the gyroscope. Gyroscope can sense the angular velocity due to vibration and it can produce corresponding electrical signal output this signal is given to Arduino. Arduino analysis the signal and
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correspondily digital output is given to motor driver .Depending up on the driver input motor moves forward and backward and balances vehicle in two wheels.
Fig. 1: Circuit Diagram of Self Balancing Vehicle
IV. HARDWARE DESCRIPTION A. Components In this section the specific components that were utilized during the experimentation and testing process are described with their principles of operation in the same order they were tested. 1) Arduino UNO R3 Arduino is a brand that produces development boards, kits and opens source software for the small and commercial projects. It is used widely around the Globe. We selected Arduino to meet our low cost requirement with reusability and market trust as major factors. There are other project boards available in market like Raspberrypi, STM development kits, TI Cortex M3/M4 boards having more IO’s than Arduino Uno board we used, but since we don’t require that much large number or IO’s for our project and this was more cost effective than the rest with variety of libraries and codes available at its community forums, providing us more ease to complete this project, Arduino was our foremost choice. Looking at the board from the top down, this is an outline of what you will see (parts of the board you might interact with in the course of normal use are highlighted):
Fig. 2: Arduino Board Elaborative Model Starting clockwise from the top centre
– – – –
Analog Reference pin (orange) Digital Ground (light green) Digital Pins 2-13 (green) Digital Pins 0-1/Serial In/Out - TX/RX (dark green) - These pins cannot be used for digital I/O (digitalRead and digitalWrite) if you are also using serial communication (e.g. Serial. Begin). All rights reserved by www.grdjournals.com
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– – – – – – –
Reset Button - S1 (dark blue) In-circuit Serial Programmer (blue- green) Analog in Pins 0-5 (light blue) Power and Ground Pins (power: orange, grounds: light orange) External Power Supply In (9-12VDC) - X1 (pink) Toggles External Power and USB Power (place jumper on two pins closest to desired supply) - SV1 (purple) USB (used for uploading sketches to the board and for serial communication between the board and the computer; can be used to power the board) (yellow) Operating Voltage Input Voltage (recommended) Input Voltage(limit) Digital I/O pins PWM Digital I/O pins Analog Input pins DC current per I/O pin DC current for 3.3V pin
5V 7-12V 6-20V 14 (of which 6 provide PWM output) 6 6 20 mA 50 mA
32 KB (ATmega328P) of which 0.5 KB used by bootloader SRAM 2 KB(ATmega328P) EEPROM 1 KB(ATmega328P) Clock speed 16MHz Length 68.6 mm Width 53.4 mm Weight 25g Table 1: General Details for ATmega328P (used on most boards) SSFlash memory
2) Inertial Measurement Unit (IMU) The MPU-60X0 is the world’s first integrated 6-axis Motion Tracking device that combines a 3-axis gyroscope, 3-axis accelerometer, and a Digital Motion Processor™ (DMP) all in a small 4x4x0.9mm package. With its dedicated I 2C sensor bus, it directly accepts inputs from an external 3-axis compass to provide a complete 9-axis Motion Fusion™ output. The MPU-60X0 Motion Tracking device, with its 6-axis integration, on-board Motion Fusion™, and run-time calibration firmware, enables manufacturers to eliminate the costly and complex selection, qualification, and system level integration of discrete 29 devices, guaranteeing optimal motion performance for consumers. The MPU- 60X0 is also designed to interface with multiple no inertial digital sensors, such as pressure sensors, on its auxiliary I2C port. The MPU-60X0 features three 16-bit analog-to-digital converters (ADCs) for digitizing the gyroscope outputs and three 16-bit ADCs for digitizing the accelerometer outputs. For precision tracking of both fast and slow motions, the parts feature a user-programmable gyroscope full-scale range of ±250, ±500, ±1000, and ±2000°/sec (dps) and a user-programmable accelerometer full-scale range of ±2g, ±4g, ±8g, and ±16g. An on-chip 1024 Byte FIFO buffer helps lower system power consumption by allowing the system processor to read the sensor data in bursts and then enter a low-power mode as the MPU collects more data. With all the necessary on-chip processing and sensor components required to support many motion- based use cases, the MPU-60X0 uniquely enables low-power Motion Interface applications in portable applications with reduced processing requirements for the system processor. By providing an integrated Motion Fusion output, the DMP in the MPU- 60X0 offloads the intensive Motion Processing computation requirements from the system processor, minimizing the need for frequent polling of the motion sensor output. Communication with all registers of the device is performed using either I2C at 400 kHz or SPI at 1MHz (MPU-6000 only). For applications requiring faster communications, the sensor and interrupt registers may be read using SPI at 20MHz (MPU-6000 only). Additional features include an embedded temperature sensor and an on-chip oscillator with ±1% variation over the operating temperature range. The part features a robust 10,000g shock tolerance, and has programmable low-pass filters for the gyroscopes, accelerometers, and the on-chip temperature sensor. For power supply flexibility, the MPU-60X0 operates from VDD power supply voltage range of 2.375V-3.46V. Additionally, the MPU-6050 provides a VLOGIC reference pin (in addition to its analog supply pin: VDD), which sets the logic levels of its I2C interface. The VLOGIC voltage may be 1.8V±5% or VDD. The MPU- 6000 and MPU-6050 are identical, except that the MPU6050 supports the I2C serial interface only, and has a separate VLOGIC reference pin. The MPU-6000 supports both I2C and SPI interfaces and has a single supply pin, VDD, which is both the device’s logic reference supply and the analog supply for the part. 3) L298N IC The L298 is an integrated monolithic circuit in a 15- lead Multiwatt and PowerSO20 packages. It is a high voltage, high current dual full-bridge driver designed to accept standard TTL logic levels and drive inductive loads such as relays, solenoids, DC and stepping motors. Two enable inputs are provided to enable or disable the device independently of the input signals. The emitters of the lower transistors of each bridge are connected together and the corresponding external terminal can be used for the connection
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of an external sensing resistor. An additional supply input is provided so that the logic works at a lower voltage. Most of the microcontrollers operate on very low voltage (5v) and current while the motors require higher voltages and current So, the microcontrollers cannot provide them such higher current. For this purpose we use motor driver ICs. Motor driver is a little current amplifier. It takes a low current signal and gives out a high current signal which can drive a motor. It can also control the direction of motor. Motor drives are of many kind depending upon the maximum supply voltage, maximum output current, rated power dissipation, load voltage and number outputs etc. Here we are going to discuss motor driver L298N. It is used in dc motor speed control project and you can interface dc motor easy with microcontroller using this motor driver. And also in Bluetooth controlled robot using pic microcontroller. You can check line follower robot for more about its application.
Fig. 3: L298N IC Pin Diagram
L298N consists of four independent power amplifiers. Two of them form H-bridge A while other two form H-bridge B. One H bridge is used to switch the polarity in controlling direction of DC motor. Pair of H Bridge is used to control a bi-polar stepper motor. – Amp A1 and A2 => H Bridge A – Amp B1 and B2 => H Bridge B Basically L298N is used to drive inductive or magnetic loads, so there can come voltage spikes in output. To avoid that voltage spikes there should be some internal parasitic or Flywheel diodes. But it lacks them. We use externally these flywheel diodes. They can be 1N5819 schottky diodes or 1N4001 rectifier diodes. Each bridge is provided with enable pins (ENA, ENB) and current sense pins (CSA, CSB). Current sense pins can be tied to ground but we can also insert low value resistor and its voltage reading is proportional to current. Both enable pins can be used at the same time which makes all for outputs active at the same time. All the four inputs and Enable pins work on 5v TTL logic which makes the connection easy with microcontrollers. 4) Geared DC Motors This motor is small, works well using a 3 or 4 AA battery pack, and is very reliable provided you don’t overload it. a) Electrical Characteristics Voltage 9Volt DC Maximum speed 25 rpm No load free speed 40 rpm No load current 0.17 amps Stall torque 20 kg-cm Stall current 1.5 amps
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Maximumoutput 10.7 watts power Gear ratio 1:52 Table 2: Electrical Characteristics of geared DC motors
b)
Operating Conditions Rated load 0.8 kgf.cm Operating -10~+60 ̊ C Temperature Storage -30~+85 ̊ C Temperature Motor Type 130 Table 3: Operating Conditions of geared DC motors
c)
Mechanical Characteristics PARAMETER Typical Capacity Minimum capacity Nominal voltage Standard Charge Standard Discharge End-ofcharge Voltage End-ofcharge Current End-ofdischarge Voltage
SPECIFICATION 7800mAh 1000mAh 3.7V CC/CV,0.2C5A, 4.2 0V CC,0.2C5A, 3.0V4.2V 4.20V±0.05V 0.01C5A (At CV mo de) 3.00 V
6.0hours(standard ch arge) Quick Charge Curre 2000mA (1.0C5rate) nt 1C Quick Discharge Cur 20000mA (10.0C5rat rent e) 10C 30000mA (20.0C5rat Max Discharge Current e) 20C Max: Less than 50 Initial Impedance Ohm Weight Approx :50±2g Operating temperature Charging: 0 ~45 Discharging:20 ~60 Storage temperature -5 ~35 Storage Humidity ≤75% RH Without scratch, distortion, Appearance contamination and leakage Temperature 2 3±5 Standard environmental condition Humidity : 45-75%RH Atmospheric Pressure : 86-106 KPA Table 4: Mechanical Characteristics of geared DC motors Charging Time
5) Batteries The various parameters of Ultrafire 18650 3.7v 7800mah Li ion Battery are tabulated below. Output mode 2 sides Gear ratio 1:48 1:120 Table 5: Specifications of BRC 18650 7800mAh Batteries
B. – – – – – – –
Advantages (Ultrafire 18650 3.7v7800mah Li i on Battery) High capacity, low inner resistance, lo ng cycle life, low self-discharge Long cycle life, more than 600 charge/ discharge cycles under normal use No memory effect, economically and conveniently. Handling performance, maintenance- free and wide application. Strong current charge and discharge capability reached IEC standard Green power, kamcy battery is free of Pb, Hg, Cr6+, PBB and PBDE Powerful output, maximize your electronic appliances performance
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–
Can be rapidly charged with any quick charger, smart chargers, and plug in charger or universal charger
V. RESULT AND DISCUSSION The paper work is completed and required output is obtained for self-balancing vehicle with gyroscope-prototype and design and derivation of transfer function of self balancing vehicle based on inverted pendulum concept without using gyroscope is 20% completed. If an object is placed on the vehicle it will balance the object by moving forward and backward. Thus it self-balances.
VI. FUTURE ENHANCEMENTS There are several promising directions for further research in self balancing vehicle. But existing one is very costly .So we can reduce the cost of Segway or self balancing vehicle by reducing the electronic components by the simple method of control system. This project provides stable base for several stability based applications, some of them are listed below: – Stabilized Video Recording Robot, with a movie-camera or a camcorder mounted on top plate of SBR. – Stable base for the launching of small satellites from remote places such as Mars, Moon etc, where low gravity could make it real difficult for a normal – Launcher to stabilize its position for the targeted trajectory. – A Serving Robot in a restaurant, with its top plate expanded to carry dishes upon its surface.
VII.
CONCLUSION
We mainly selected this project for various applications of self balancing requirements. Self balancing is of great importance today, mainly in balancing the load transportation in railway platforms and such similar applications.
REFERENCES [1] Mr. Andrew Blake, Dr. Grahm Winstanley, Dr. William Wilkinson, “Deriving Displacement from a 3-Axis Accelerometer,” University of Birghton CMIS, Watts Building, Lewes Road, Brighton, vol. 1, p. 6, 2010. [2] R. C. Ooi, “Balancing a two wheeled Autonomous Robot,” The University of Western Australia, School of Mechanical Engineering, NedLands, WA, 2003. [3] F. T. Christian Sundin, “Autonomous balancing Robot,” Department of Signals and Systems, Chalmers University of Technology, Gotebrog, Sweden, 2012. [4] N. G. P. N. Brian Bonafilia, “Self- Balancing Two-Wheeled Robot,” Imperical College, London, London, UK, 2012. [5] K. A. O. I. A. H. M. Q. A. Umar Adeel, [6] “Autonomous Dual Wheel Robot based on Microcontroller,” Journal of basic and applied scientific research, vol. 1, no. ISSN2090- 4304, p. 6, 2013. [7] M. B. M. Ali, “Development of Self- Balancing Platform on Mobile Robot using PID Controller,” Faculty of Electrical and Electronic Engineering, Universiti tun Hussein Onn Malaysia, Malay, Malaysia, June,2013. [8] A. Castro, “Modeling and Dynamic Analysis of Two Wheeled Inverted Pendulum,” George W. Woodruff School of Mechanical Engineering, Georgia Institute of Technology, Georgia, US, Aug, 2012 [9] https://www.instructables.com/i d/Self-Balancing-Robot/ [10] https://create.arduino.cc/project hub/s r-tronics/self-balancing-robot- using-mpu-6050-accelerometer- 74d57d
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