DESIGN OF A LIGHTWEIGHT, MODULAR ROBOTIC VEHICLE FOR THE SUSTAINABLE INTENSIFICATION OF BROADACRE AGRICULTURE Owen John Bawden Bachelor of Industrial Design (Hons) Supervisors Dr David Ball, Prof. Tristan Perez, Prof. Peter Corke. Submitted in fulfilment of the requirements for the degree of BN72 - Master of Engineering (Research) School of Electrical Engineering and Computer Science Science and Engineering Faculty Queensland University of Technology June 2015 Keywords Agriculture, Agricultural Robotics, Broadacre Farming, Integrated Weed Management, Lightweight Vehicle Design, Robotic Vehicles, Future Farming Systems, Precision Agriculture, Industrial Design, Engineering, User Centred Design. Design of a Lightweight, Modular Robotic Vehicle for the Sustainable Intensification of Broadacre Agriculture i Abstract This thesis presents the design process and the prototyping of a lightweight, modular robotic vehicle for the sustainable intensification of broadacre agriculture. The latter is to be achieved by the joint operation of multiple autonomous vehicles that can improve energy consumption, reduce labour, and increase efficiency in the application of inputs for the management of crops. The introduction of robotics in agriculture can be seen as a revolutionary step away from the current direction in farming of increasingly large machines designed to optimise an individual farmer’s productivity. Larger machines cause severe subsoil compaction issues and greater machinery complexity resulting in longer disruptions from single vehicle failure. In addition, Australian farmers are facing increasing levels of herbicide resistance in weeds, a problem costing 4 billion dollars a year. Losses are occurring in production efficiency because large farm machinery can no longer mitigate weeds using current management modalities. The field of agricultural robotics is responding to these challenges by developing robots that can operate with greater effectiveness, for longer hours and at less cost than traditional farm machinery and labour. The Small Robotic Farm Vehicle (SRFV) is a lightweight and energy efficient robotic vehicle with a configurable, modular design, which enables interchangeable implement units to span between the modular side units. The SRFV is capable of undertaking a range of agricultural tasks, including seeding, fertilising and weed management through mechanical intervention and precision spraying. The robot is designed to be more than an order of magnitude lower in weight than existing broadacre agricultural equipment. The vehicle is based on a four wheel configuration, capable of bi-directional driving through the use of differential steering wheels and caster wheels. Travelling at a maximum speed of 10km/hr, the vehicle is driven by two 5kW electric in-hub motors powered by Lithium Iron Phosphate (LiFePO4) batteries. The prototype vehicle has been developed using the latest rapid manufacture technologies and incorporates aesthetic features unique to agricultural robotics. ii Design of a Lightweight, Modular Robotic Vehicle for the Sustainable Intensification of Broadacre Agriculture Incorporating aspects of engineering and industrial design practices, this project uses a user-centred design model, weaving human factors into technical problem solving. This approach to innovation draws from the designers and engineer’s toolkit to integrate the needs of people, the possibilities of technology, and the requirements for business success. This thesis presents a design methodology suitable for autonomous farm vehicles and applies it to the design and prototyping of the SRFV. The images below depict the completed SRFV prototype. Design of a Lightweight, Modular Robotic Vehicle for the Sustainable Intensification of Broadacre Agriculture iii Table of Contents Keywords ...................................................................................................................... i Abstract ........................................................................................................................ ii List of Figures ............................................................................................................ vii List of Tables ............................................................................................................... xi List of Abbreviations .................................................................................................. xii Statement of Original Authorship ............................................................................. xiii Acknowledgements ................................................................................................... xiv Chapter 1: Introduction ...................................................................................... 1 1.1 Background ......................................................................................................... 1 1.2 Project Overview ................................................................................................ 4 1.2.1 Objectives .................................................................................................. 4 1.2.2 Scope ......................................................................................................... 4 1.3 Project Benefits ................................................................................................... 5 1.4 Project Stakeholders ........................................................................................... 6 1.5 Project Methodology ........................................................................................... 6 Chapter 2: Research .......................................................................................... 11 2.1 Literature Review ............................................................................................. 11 2.1.1 Overview ................................................................................................. 11 2.1.2 Australian Agricultural Challenges ......................................................... 13 2.1.3 Research into Agricultural Robotic Vehicles .......................................... 16 2.2 Market Analysis ................................................................................................ 22 2.3 Initial Feedback From Farmers ......................................................................... 26 2.4 Establishing Key Research Themes .................................................................. 31 Chapter 3: General Requirements and Specifications ................................... 33 3.1 Objective ........................................................................................................... 33 3.2 General Robot Requirements ............................................................................ 33 3.3 Vehicle Parameters ........................................................................................... 35 3.4 Vehicle Dimensions .......................................................................................... 35 3.5 Vehicle Mass ..................................................................................................... 42 3.6 Vehicle Coverage .............................................................................................. 44 3.7 Operating Speed ................................................................................................ 46 3.8 Operating Time ................................................................................................. 47 3.9 Operating Gradients .......................................................................................... 48 3.10 Vehicle Configuration ....................................................................................... 49 iv Design of a Lightweight, Modular Robotic Vehicle for the Sustainable Intensification of Broadacre Agriculture 3.10.1 Manoeuvrability .................................................................................... 49 3.10.2 Stability ................................................................................................. 50 3.10.3 Tracked vs Wheeled Vehicles ............................................................... 51 3.10.4 Four Wheel Drive, Rear Wheel Drive or Front Wheel Drive. .............. 51 3.10.5 Suspension ............................................................................................ 52 3.11 Configuration Analysis ..................................................................................... 52 3.12 Resultant Configuration .................................................................................... 58 3.13 Key Vehicle Parameters ................................................................................... 59 3.14 Conceptual Design Development - Sketches .................................................... 61 3.15 Conceptual Design Development - Renderings ................................................ 62 3.16 Concept Vehicle Design ................................................................................... 63 3.17 Vehicle Specification ........................................................................................ 64 Chapter 4: Detailed Vehicle Design .................................................................. 65 4.1 Overall Dimensions .......................................................................................... 66 4.2 Vehicle Chassis ................................................................................................. 67 4.3