Robot Study/Introduction to Robotics

Information

Purpose: Learning basic knowledge of robotics Lecture: CS223A, Stanford University Date: Jan 21, 2019 ~

• Prerequite
• Linear Algebra
• Numerical Analysis

Reference

Material: Copy from Stanford Video clips: https://www.youtube.com/watch?v=0yD3uBshJB0&list=PL65CC0384A1798ADF

Study List

Lecture 1

Video Clip

OT

Book

General Manipulator: Robot Arm, using Revolute joint, Prismatic joint

• Robot Arm: base, link, joint, end-effector
• Revolute joint: Rotation movement, 1 Degree of Fredom(DoF)
• Prismatic joint: Linear movement, 1 DoF
• Denote joint type using ε(0 for revolute, 1for prismatic)

Discription of body1 (9 parameters)

• Link location: 3 points (Each point has 3 parameters)

Discription of body2 (6 parameters)

• Body orientation: 3 parameter
• Point on the body: 3 parameter

=> Robot arm(n:links, 1: base) has n DoF

Transformation

• Pure Rotation
• Pure Translation
• General Tasformation
• Inverse Transformation

Configuration Representation There is no universial agreement in the field of robotics as to what is the best orientation representation. Because each representation hase advantages and shortcomings

• Direction Cosines:
• Euler angle representation: ZYX, angle(α, β, γ)
• Fixed angle representation: XYZ, angle(γ, β, α)
• Inverse of an orientation representation

Lecture 2

Video Clip

Kinematics

• Spatial Description

-Task Description

• Transformation
• Representations

Robot arm

• Manipulator: Set of link through the joint
• First link: Base
• Last linke: End-Effector

Book: Direct Kinematics

Previous

• Independent of the structure of the manipulator

Introduction

• A set of parameters specific to each manipulator
• ex) rotation, translation, link of manipulator
• Forware Kinematics
• Inverse Kinematics

Link Description

• Manipulator: Consist of a chain of links from base
• Consecutive links are connected by joints which exert the degree of freedom.

D-H Parameter

• link length(a): length along the common normal from axis (i-1) to axis i
• link twist(α): angle between this parallel line and axis (i-1)
• link offset(θ): distance alont the line on axis i between the common normal for link (i-1) and common normal for link i
• joint angle(d): angle between the two common normal for link (i-1) and common normal for link i
• Revolute joint: joint angle(variable), link offset(constant)
• Prismatic joint: joint angle(constant), link offset(variable)
• a, α: describe link
• d, θ: describe the link's connection

Conventions for First and Last Link

• Once robot structure is set link length & link twist is determined.
• a(i) and α(i) depend on joint axes i and i+1

Axes 1 to n: determined => a(1), a(2), ,,,, a(n-1) and α(1), α(2), ,,,,a(n-1)

• d(i) and θ(i) depend on

Attaching Frames to links

Comments

선배님 너무 멋있어여 - 조예진

• 새싹 준비입니다 - 우준혁