EL410: Introduction to Robotics
Lecture-5
Robotic Arm
Digikey: https://www.digikey.in/en/products/detail/arduino/T050000/6829063
https://media.digikey.com/pdf/Data%20Sheets/Arduino%20PDFs/Braccio_QSG.pdf
Arduino
https://docs.arduino.cc/retired/getting-started-guides/Braccio
ROS
https://github.com/smart-methods/arduino_robot_arm
https://github.com/smart-methods/robot_arm_arduino_python
https://github.com/smart-methods/arduino_robot_arm_gripper
2
Robotics Graphics
3
Languages for 3D Robot Modeling
• URDF
• Xacro
JVRC Robot model represent in
3D Computer Graphics (CG)
4
What is URDF
• URDF (Unified Robot Description Format) is an XML
format for describing the structure of a robot.
• URDF can be displayed in 3D with rviz or physically
simulated with Gazebo.
• URDF files have a .urdf file extension.
• The description in URDF consists of Link and Joint.
5
Robot Model
6
Coordinate System
z
Yaw
Pitch
Roll
y
x
• Cartesian coordinate system (x, y z)
• Rotational coordinate system (Roll, Pitch, Yaw)7
Units
Set value
length
angle
mass
unit
m
radian
Kg
Power (translation)
N-m
Force (rotation)
N
Speed ​(translation)
m/s
Speed ​(rotation)
radian / s
8
Joint
Set value
fixed
revolute
continuous
floating
planar
meaning
Fixed
Rotation with limited
operating angle
Continuous rotation
------------9
Basic Shape
Set value
cylinder
box
sphere
mesh
meaning
Cylinder
box
ball
mesh
10
Writing URDF File
<robot name="test_robot">
<material name="red">
<color rgba="1.0 0.0 0.0 2.0"/>
</material>
<link name="base_link"/>
<joint name="body1_joint" type="fixed">
<parent link="base_link"/>
<child link="body1_link"/>
</joint>
<link name="body1_link">
<visual>
<geometry>
<box size="0.1 0.1 0.5"/>
</geometry>
<origin xyz="0 0 0.25" rpy="0 0 0"/>
<material name="red"/>
</visual>
</link>
<joint name="body2_joint" type="revolute">
<parent link="body1_link"/>
<child link="body2_link"/>
<origin xyz="0.1 0 0.5" rpy="0 0 0"/>
<limit lower="-1.5" upper="1.5" effort="0" velocity="0"/>
</joint>
<link name="body2_link">
<visual>
<geometry>
<box size="0.1 0.1 0.4"/>
</geometry>
<origin xyz="0 0 0.2" rpy="0 0 0"/>
<material name="red"/>
</visual>
</link>
<joint name="body3_joint" type="revolute">
<parent link="body2_link"/>
<child link="body3_link"/>
<origin xyz="0.1 0 0.4" rpy="0 0 0"/>
<limit lower="-1.5" upper="1.5" effort="0" velocity="0"/>
</joint>
<link name="body3_link">
<visual>
<geometry>
<box size="0.1 0.1 0.4"/>
</geometry>
<origin xyz="0 0 0.2" rpy="0 0 0"/>
<material name="red"/>
</visual>
</link>
</robot>
11
3D Computer Graphics Created using URDF File
12
Definition for Physics Simulation
<link name="base">
:
<!--collision detect area-->
<collision>
<geometry>
<box size="0.02 0.02 0.1"/>
</geometry>
</collision>
<!--inertia matrix-->
<inertial>
<mass value="0.1"/>
<inertia ixx="1.0" ixy="0.0" ixz="0.2" iyy="1.0" iyz="0.0" izz="0.0"/>
</inertial>
:
</link>
13
Calculation Formula of Inertia Matrix
Ixx Ixy Ixz
Iyx Iyy Iyz
Izx Iyz Izz
14
Box Inertia Matrix
c
b
a
1
𝐼𝑥𝑥 = 𝑚 𝑏 2 + 𝑐 2
2
1
𝐼𝑦𝑦 = 𝑚 𝑐 2 + 𝑎2
2
1
𝐼𝑧𝑧 = 𝑚 𝑎2 + 𝑏 2
2
15
Solid Sphere Inertia Matrix
R
h
𝐼𝑥𝑥
1
𝐼𝑧𝑧 = 𝑚𝑅2
2
1
= 𝐼𝑦𝑦 =
𝑚 3𝑅2 + ℎ2
12
16
Cylindrical Inertial Matrix
R
𝐼𝑥𝑥 = 𝐼𝑦𝑦 = 𝐼𝑧𝑧
2
= 𝑚𝑅2
5
17
Homework: JVRC Humanoid Robot Model
18
Humanoid Links and Joint Connections
19