Design, modelling and simulation of 2 novel 6 DOF hybrid machines.

This thesis has not been submitted for any degree or examination at any other university. iii). This thesis does not contain data, images, graphs or other information from other persons, unless it is explicitly stated that they originate from other persons. This thesis does not contain the writings of other persons, unless it is expressly acknowledged that they originate from other researchers.

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Acknowledgements

Abstract

Acronyms

Terms

Reach - The maximum radial distance that the robot can place its end-effector tip from the robot's base origin. Resolution - The smallest increment of motion or distance that a robot end effector or joint angles can make. Isotropy – The isotropy of a robotic manipulator is related to the number of terms of its Jacobi matrix.

Mathematical Modeling – The mathematical modeling was limited to the designers' kinematics, dynamics (which excludes payload) and estimated energy consumption. Simulation – The simulations performed only rigid body calculations, bending and flexibility of components were not considered. Euler angles could be used to describe the movement of the end effector relative to the wrist center.

Carricato developed a manipulator exhibiting 4 DOF Schoenflies motion, i.e., the mobile platform could be freely translated in space and rotated around a fixed direction. This can be used for load carrying capacity or for good end effect control. It controlled the height of the lower arm (proximal arm) in relation to the horizontal plane.

A fourth bevel gear controlled elevation of the proximal arm relative to the horizontal plane. In this design, the outermost part of the wrist shifter was attached to the distal arm. The second section controlled the elevation of the end effector joint relative to the distal joint (wrist axis 2).

A scaled model of the first design is built and controls only in the forward kinematics sense. The position and orientation of the end effector with respect to the base frame (T60) was obtained from the multiplication T10. There are 2 standard methods used to calculate the dynamics of robots, that is, the iterative Newton-Euler and energy-based Lagrangian techniques.

The inertia tensor of the H-links (proximal and distal) in this design was derived in the same way as the previous one, using rectangular bar moments of inertia for each constituent part of the link (holes and rounded sections were ignored). The complete proximal arm was composed of the structural part (ie, the cylinder) and the motor that actuated the distal arm. The outer radii of the cylinders were rp(i) and rd(k) (for i=1 to 5 and k=1 to 4) for the proximal and distal parts, respectively.

Each of the 5 cylinders in the proximal wing had mass mp(i), outer radius rp(i), inner radius.

Figure 1: Comparative illustrations of a PKM and SKM

Index of figures

Index of tables

Introduction

Motivation for study
Problem statement
Project aims
Project objectives
Limitations
Project specifications
Research publications
Thesis outline
Chapter summary

A parallel kinematics architecture, on the other hand, fixed the location and arrangement of the actuators at the stationary robot base. The actual design of the SKM by virtue of the SKM definition could not improve the robot's performance. This information only affected the dynamic modeling of the serial robot as it carried all its motors.

Comparative studies – These were conducted on simplified, ideal mathematical models of the hybrid designs and a standard serial robot. Simulations were also performed for circular paths, varying each of the first 3 corners separately. The chapters provided a logical division of the project into its key components and contributions, and are outlined below.

Chapter 1, Introduction – Introduces the topic of the thesis, and lists project goals, objectives, specifications and publications. Chapter 2, Literature Review – Presented a review of some series, parallel and hybrid kinematics robots, and illustrated some of the more popular ones.

Literature review

General benefits and trends of industrial robots
Classification of industrial robot architectures
Comparison of parallel and serial architectures
Industrial robot arm designs
Parallel industrial robot designs
Hybrid industrial robot designs
Singularities
Justification for a new robot design
Chapter summary

M2VIP11, 18th International Conference on Mechatronics and Machine Vision in Practice, 6-7 December 2011, Brisbane, Australia: "Novel light-weight 6 DOF robotic arm", A.A. IJISTA 2012, International Journal of Intelligent Systems, Technologies and Applications: "A New Hybrid Machine Design for a 6 DOF Industrial Robot Arm", A.A. Chapter 3, Mechanical Design and Modeling – Presented the mechanical designs of 2 HKMs, as well as a detailed functional description of the.

Mechanical design

Concept and design novelty
Design description

Methods to improve robot's positioning accuracy
Base concentric geared mechanisms (BCGMs)
Torque transfer methods
Wrist designs
Complete designs

Design classification
Prior art search
System modelling

Forward kinematics
Inverse kinematics
Torque/force transfer
Machine level kinematics
Machine level dynamics

Chapter summary

Scaled functional model

Motor control
Servo drives and control for a real, full-scale robot
Scaled model of design 1
Chapter summary

Simulation results

Design 1: Primary 3 bar slider-pivot linkage
Design 1: Secondary 3 bar slider-pivot linkage
Machine level kinematics simulation
Machine level dynamics simulation
Multi-straight line path simulation results

Multi-vertical line paths
Multi-horizontal line paths
Multi-radial line paths

Circular path simulation results

Varying angle 1 only

Serial robot's static balancing at joint axis 3
Chapter summary

Conclusion

Serial robots in general were optimized with little thought to the total mass of the system. Sufficient material will be saved on the correct side of the disc for cutting gear teeth. Furthermore, the follower on the end of the primary slider-pivot connection became the driver for the secondary stage.

The outermost movable section (or the third section in the wrist concentric gear drive) rotated the wrist (this was the fourth robot axis) and had mounts for the inner 2 axes of the 3 DOF wrist. If, on the other hand, the robot came to rest at the end of the path, it was set to zero. For the H-joints (main proximal and distal joints), solid rectangular bars were used to model the component parts of the joints.

The inertia tensor of the third motor (actuator axis 3) modeled as a rectangular block is given by. The inner radii for the proximal tubes are given by rp(i1) (for i=1 to 5), where rp(0) is the inner radius of the first tube. Also for the model, the axes of these gears will remain parallel to the axes of the concentric cylinders in the proximal link for the entire movement.

The elbow motor (motor 3) was then 35% of the combined mass of the distal joint and wrist motors.