Abstract: Yaw, Pitch, Roll, Axis. I. Introduction This project

Abstract: Inertial measuring Unit (IMU) is an
integrated chip that has an on-board accelerometer and gyroscope. The
application using this chip is infinite and vivid, this paper dives into the
automation paradigm of the IMU and we intend to develop a system that enables
an automobile to drive through a bumpy road with ease and smoothness. The
values provided by the IMU gives a steady reference with respect to the ground
for the microprocessor to process the information and adjust the position of
wheels.

Keywords: IMU, Accelerometer,
Gyroscope, DoF, Yaw, Pitch, Roll, Axis.

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I.     
Introduction

 

This project will serve as a
prototype which can be further implemented in large scale with help of this
unit we are able to track position an object to which this unit is attached in real-time

This project can be related to hand
gesture project, but this project has a capability to track as well as log
position parameters as well                          

 Power management has been one of the most
discussed topic in the past decade because of the decrease in the energy
reserves. Power shutdown is a major problem now-a-days and it occurs because a
lot of power is wasted in industries.

1.1   
Importance
of the project and its background:

 

?             Real time tracking

?             Accurate results

?             Data recording

?             Energy
Saving

 

II.   Methodology

 

Real
time motion tracking technology is the upcoming high end technology. Wireless
transmission of the coordinates after processing various parameters like linear
acceleration, angular momentum, magnetic flux after its integration into a
processor, which provides the position of the object to which the IMU is
attached.

We have designed this project with
minimum external modules and peripherals making it cost effective

A.   
 Types of IMU

IMU available in market now are in
various types and shape. So, user can select what type, size and shape. The IMU
can be selected from its degrees of freedom (DOF) that being developed by
manufacturer. User can select from three DOF, five DOF and six DOF. For three
DOF, the sensors configurations are two accelerometers and a gyroscope that
measures yaw. For five DOF, the sensors configurations are three accelerometers
and two gyroscopes that measure pitch and roll. For six DOF, all axes for
accelerometer and gyroscope for measurement are available.

A.   
About
MPU-6050 Six-Axis (Gyro + Accelerometer)

The MPU-6050 devices combine a
3-axis gyroscope and a 3-axis accelerometer on the same silicon die, together
with an on board Digital Motion Processor™ (DMP™), which processes complex
6-axis Motion Fusion algorithms. The device can access external magnetometers
or other sensors through an auxiliary master I²C bus, allowing the devices to
gather a full set of sensor data without intervention from the system
processor. The devices are offered in a 4 mm x 4 mm x 0.9 mm QFN package.

                    Fig. 1 MPU 6050

 

B.   
 MPU 6050 features:

·        
I2C Interface.

·        
Supply voltage: 3 to 5 V.

·        
I/O voltage: 2.3 to 3.4 V.

·        
Triple axis gyro (angular rate sensor) with selectable
scale (from ±250 to ±2000 dps)

·        
Triple axis accelerometer with selectable scale (from ±2g
to ±16g)

·        
Temperature sensor with digital output.

·        
Digital Motion Processing™

·        
Size: 20 mm x 15 mm.

 

 

Fig 2. Block Diagram of MPU 6050

For precision tracking of both fast
and slow motions, the parts feature a user-programmable gyro 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. Additional features
include an embedded temperature sensor and an on-chip oscillator with ±1%
variation over the operating temperature range.

Formula:

Required_value=                     (1)

C.   
Scope
of the project.

This project has a very wide scope
in visual reality where ever minute motion is tracked and analysed to produce
an amazing life-like experience. The air bags in vehicles needs to be deployed
on a specific degree of Impact, it should not malfunction and deploy on minor
jerk or on applying brakes. If it happens so then the safety system might
itself result into a mishap. Hence in order to sense the impact IMU can be used
which can be calibrated to trigger on a specific intensity of impact. As the
technology is advancing the is much more research activity in domain of Real
time motion tracking.

D.   
 Current scenario

Currently in order to track any
object in 3- dimension we need complex wiring and grid of sensors for its real
time tracking or we can track it using GPS but there are some limitations to
it, like the position is not accurate and may vary due to environmental
conditions and other physical parameters.

E.   
 The proposed system

The system which we have proposed is
very compact is size and hence it can be attached to any moving object like
vehicles or on humans. The proposed change makes our system wearable as well as
the components used in it makes the complete device cost effective and rugged.
The inertial measurement unit works by detecting linear acceleration using one
or more accelerometers and rotational rate using one or more gyroscopes. A
magnetometer is utilized, which is commonly used as a heading reference.
Typical configurations contain one accelerometer, gyro, and magnetometer per
axis for each of the three vehicle axes: pitch, roll and yaw. Due to the
presence of on board accelerometer, gyroscope and magnetometer on a single chip
and with a central processor too the values are obtained in a systematic manner
and these sensors provide our project with the ability to have nine degrees of
freedom for motion tracking.

F.   
 3D orientation of MPU 6050

 

Fig 3. Orientation of Axes of Sensitivity and polarity of
rotation

 

G.   
 Block diagram

 

Fig 4. Block Diagram

2.9 Design Phase: Circuit Diagram

Fig 5. Interfacing IMU with Arduino

2.10 Interfacing the Arduino MPU
6050

The MPU 6050 communicates with the
Arduino through the I2C protocol. The MPU 6050 is connected to Arduino as shown
in the following diagram. If your MPU 6050 module has a 5V pin, then you can
connect it to your Arduino’s 5V pin. If not, you will have to connect it to the
3.3V pin. Next, the GND of the Arduino is connected to the GND of the MPU 6050.

The program we will be running here,
also takes advantage of the Arduino’s interrupt pin. Connect your Arduino’s
digital pin 2 (interrupt pin 0) to the pin labelled as INT on the MPU 6050.
Next, we need to set up the I2C lines. To do this, connect the pin labelled SDA
on the MPU 6050 to the Arduino’s analog pin 4 (SDA) and the pin labelled as SCL
on the MPU 6050 to the Arduino’s analog pin 5 (SCL). That’s it, you have
finished wiring up the Arduino MPU 6050!

III.
 Literature Survey

 

A.   
How does accelerometer works:

 

Basic working
of Accelerometer Operation:

According to newtons second law of
motion that the acceleration (m/s2) of body is directly proportional
to the net force acting on that body, and inversely to its mass

Acceleration=Force(Newton)(m/s2)
*Mass (gram)

 

A micro Gimbal like
mechanism which is used to detect the force in a particular direction. It
basically measures acceleration through the force applied to one of the
accelerometers axes.

 

An accelerometer is an electromechanical
device, including holes, cavities, springs, and channel, that is fabricated
using microfabrication technology. Accelerometers are fabricated using a multi
– layer wafer process,

 

i.    Piezoelectric Effect

 

A accelerometer works on piezoelectric
effect. Let us imagine a cuboidal box with a small ball inside it, like shown
in the diagram below. The walls of this box are made with piezoelectric
crystals, if the box tilt on any of its side, the makes the box inclined and
the gravity forces it to collide with the wall on that particular side, this
results into production of piezoelectric current. Six walls in pair of three
corresponds to 3 axis in 3D space. X, Y and Z Axes. Depending on the current
produced from piezoelectric walls, we can determine the direction of
inclination and its magnitude.

 

 

    Fig 6. Piezoelectric Accelerometer

ii.   Capacitive Effect

 

In case of accelerometer that works on
capacitive sensing, outputs a voltage dependent on the distance between two
planar capacitive surfaces. Both these plates are charged with an electrical
current. As the gap between the plates changes the electrical capacity of the
system, which can be measured as voltage output. This method of sensing results
in high accuracy and stability. As capacitors are less affected by noise and
other electromagnetic interference, the same goes with this type of
accelerometer hence they are less prone to noise and variation with temperature
and the typically dissipate less power, and can have large bandwidths, due to
internal frequency circuits.

 

      Fig 7 Acceleration associated with a single moving mass

 Fig 8. Acceleration associated with multiple masses

Fig 9. Mechanical model of 2-axis accelerometer

Basic
working of Gyroscope

Gyroscopes work on the principle of Coriolis acceleration.
Imagine that there is a fork-like structure that is in a constant back and
forth motion. It is held in place using piezoelectric crystals. Whenever you
try to tilt this arrangement, the crystals experience a force in the direction
of inclination. This is caused as a result of the inertia of the moving fork.
The crystals thus produce a current in consensus with the piezoelectric effect,
and this current is amplified. The values are then refined by the host
microcontroller.

Tuning Fork
Gyroscope:

This type of Gyroscope contains  a pair of masses that are driven to oscillate
with equal amplitude but in opposite directions. While rotating the Coriolis
force  creates an orthogonal vibration
which can be sensed by many types of mechanism. The figure below (Figure:9)
uses comb type structure to drive the tuning force into resonance

Fig 10. Comb type Tuning Fork Gyroscope Structure

The
rotation caused the mass to vibrate which in turn vibrate out of the plane,
this type of motion is sensed by the structure

 

IV.
Result and Discussion

 

 

      Fig 11. Result of 3D simulation

 

1.       Raw data of accelerometer

 

Table 1. X-axis Readings

Ax

Range

Sensitivity

X-Axis

-15608

2g

16384

0.95g

-945

4g

8192

0.11g

256

8g

4096

0.06g

2655

16g

2048

0.8g

 

Table 2. Y-axis Readings

Ay

Range

Sensitivity

Y-axis

5065

2g

16384

0.31

-4856

4g

8192

0.59g

-255

8g

4096

0.06g

-589

16g

2048

0.28g

 

Table 3. Z-axis Readings

Az

Range

Sensitivity

Z-axis

450

2g

16384

0.027g

8159

4g

8192

0.99g

-3698

8g

4096

0.9g

898

16g

2048

0.43g

 

2.      
Raw
data of  gyroscope:

 

Table 4. X-axis Readings

Gx

Range

Sensitivity

X-Axis

-349

250

131

-2.66

65497

500

65.5

499.977

894

1000

32.8

27.25

2655

2000

16.4

161

 

Table 5. Y-axis Readings

Gy

Range

Sensitivity

Y-axis

-204

250

131

-1.355

31

500

65.5

0.756

6512

1000

32.8

198.53

-589

2000

16.4

-35.91

 

Table 6. Z-axis Readings

Gz

Range

Sensitivity

Z-axis

-247

250

131

-1.88

41

500

65.5

0.311

23645

1000

32.8

720.88

898

2000

16.4

54.75

 

 

V.   
Conclusion

 

By the realization of the above proposed system we can
not only track real-time position of an object in 3-Dimension but also use the
data for many other applications after processing it using various algorithm
depending on the