title: The effect of dimensional parameters on the dynamic performance of over-arch differential drive vehicles

authors: Tattersall, Andrew

subjects: Vehicle

abstract: This work contributes to the field of agricultural vehicle dynamics by assessing the dimensional sensitivity of over-arch differential drive vehicle performance. The findings from this work are important for vehicle optimisation with regards to drive forces, energy consumption, chassis loading, and vehicle stability. Dimensional optimisation of the vehicles has been ignored, which is a problem if efficient and environmentally friendly autonomous over-arch agricultural vehicles are to be built.

Worldwide, one in nine people do not have enough food to eat. The World Food Program has a goal to end hunger and improve the quality of available food by 2030. In New Zealand, the agricultural industry contributes $13.8 billion dollars to annual GDP and is growing, making agriculture’s contribution valuable to the New Zealand economy. However, there is a labour shortage in agriculture. This shortage of labour negatively effects food production. One potential solution to the labour shortage is automation.

Differential drive mobile robots (DDMRs) are often used in agricultural automation research because they are simple and cheap to build, and the drive system is ideal for an over-arch chassis design. Over-arch vehicles are often required in vineyards and apple orchards. Research into DDMRs is largely limited to optimisation of control and path tracking, but optimisation of the physical vehicle has been ignored. In order to optimise vehicle dimensions before manufacturing starts, the influence of dimensions on drive forces, energy consumption, chassis loading, and vehicle stability needs to be assessed.

In this study, a dynamic model of a large scale agricultural over-arch DDMR is constructed and the dimensional sensitivity of peak drive/braking force, energy consumption, chassis shear force and lateral chassis splay/compression force is assessed. The effects of caster trail and the lateral position of the center of mass on stability are also assessed. Results show that peak drive/braking force, energy consumption, stability and chassis loading are all sensitive to vehicle dimensions to different degrees. Energy consumption showed the least sensitivity, while forces were found to be significantly influenced. For a large scale DDMR traversing common agricultural trajectories, increasing caster trail by 0.2 m, decreasing longitudinal position of the center of mass by 0.2 m, and increasing track width by 0.2 m provides a decrease in peak drive force of 56.4 %, 13.9 % and 9.37 % respectively. These sample results illustrate the importance of understanding dimensional sensitivity, because they are not insignificant. The dimensional sensitivities were also found to be a good guide for vehicles of smaller scale. A case study was conducted on a Simulink model of a large scale over-arch DDMR designed for operating in vineyards. Dimensional optimisation was successfully performed such that the vehicle was able to operate adequately in the simulated vineyard environment. The case study illustrates that dimensional sensitivity is useful for the optimisation of a vehicle for its intended working environment.

This works shows that physical optimisation of these vehicles is extremely important. If optimised, savings could be found in energy consumption, cost, and materials. As automation becomes more important, accurate vehicle control is essential for performance and safety, and the work in this thesis helps to achieve this. The products of dimensional optimisation benefit the overall effort to fill the labour gap and supply enough food for the worlds growing population.

text: The effect of dimensional parameters on the dynamic performance of over-arch differential drive vehicles This work contributes to the field of agricultural vehicle dynamics by assessing the dimensional sensitivity of over-arch differential drive vehicle performance. The findings from this work are important for vehicle optimisation with regards to drive forces, energy consumption, chassis loading, and vehicle stability. Dimensional optimisation of the vehicles has been ignored, which is a problem if efficient and environmentally friendly autonomous over-arch agricultural vehicles are to be built.

Worldwide, one in nine people do not have enough food to eat. The World Food Program has a goal to end hunger and improve the quality of available food by 2030. In New Zealand, the agricultural industry contributes $13.8 billion dollars to annual GDP and is growing, making agriculture’s contribution valuable to the New Zealand economy. However, there is a labour shortage in agriculture. This shortage of labour negatively effects food production. One potential solution to the labour shortage is automation.

Differential drive mobile robots (DDMRs) are often used in agricultural automation research because they are simple and cheap to build, and the drive system is ideal for an over-arch chassis design. Over-arch vehicles are often required in vineyards and apple orchards. Research into DDMRs is largely limited to optimisation of control and path tracking, but optimisation of the physical vehicle has been ignored. In order to optimise vehicle dimensions before manufacturing starts, the influence of dimensions on drive forces, energy consumption, chassis loading, and vehicle stability needs to be assessed.

In this study, a dynamic model of a large scale agricultural over-arch DDMR is constructed and the dimensional sensitivity of peak drive/braking force, energy consumption, chassis shear force and lateral chassis splay/compression force is assessed. The effects of caster trail and the lateral position of the center of mass on stability are also assessed. Results show that peak drive/braking force, energy consumption, stability and chassis loading are all sensitive to vehicle dimensions to different degrees. Energy consumption showed the least sensitivity, while forces were found to be significantly influenced. For a large scale DDMR traversing common agricultural trajectories, increasing caster trail by 0.2 m, decreasing longitudinal position of the center of mass by 0.2 m, and increasing track width by 0.2 m provides a decrease in peak drive force of 56.4 %, 13.9 % and 9.37 % respectively. These sample results illustrate the importance of understanding dimensional sensitivity, because they are not insignificant. The dimensional sensitivities were also found to be a good guide for vehicles of smaller scale. A case study was conducted on a Simulink model of a large scale over-arch DDMR designed for operating in vineyards. Dimensional optimisation was successfully performed such that the vehicle was able to operate adequately in the simulated vineyard environment. The case study illustrates that dimensional sensitivity is useful for the optimisation of a vehicle for its intended working environment.

This works shows that physical optimisation of these vehicles is extremely important. If optimised, savings could be found in energy consumption, cost, and materials. As automation becomes more important, accurate vehicle control is essential for performance and safety, and the work in this thesis helps to achieve this. The products of dimensional optimisation benefit the overall effort to fill the labour gap and supply enough food for the worlds growing population.

year: 2022

title: Building an excellent foundation for research: Challenges and current research needs

authors: Zegwaard, Karsten E.

subjects: research-informed education

abstract: The delivery of research-informed education is a fundamental principle held by universities and is a principle that work-integrated education (WIL) should not be exempt from. In the 1980s and 1990s, critical reviews of the WIL literature suggested WIL research required significant development. Since these reviews were conducted a significant, well-developed body of literature has formed and increasingly WIL models of delivery are relying on research findings to inform program design. However, despite these successes, significant challenges and research gaps still exist. Authors in this APJCE special issue have given attention to a number of areas that present as challenges. The area of negative and neglected research findings are highlighted and the reexamining the nature of the relationship between the student and workplace supervisor has been discussed. A model of enabling transformative learning is presented and an investigation of the influence of WIL experiences on undergraduate student study direction choices has been reported. Other areas in need of further research attention are also discussed.

text: Building an excellent foundation for research: Challenges and current research needs The delivery of research-informed education is a fundamental principle held by universities and is a principle that work-integrated education (WIL) should not be exempt from. In the 1980s and 1990s, critical reviews of the WIL literature suggested WIL research required significant development. Since these reviews were conducted a significant, well-developed body of literature has formed and increasingly WIL models of delivery are relying on research findings to inform program design. However, despite these successes, significant challenges and research gaps still exist. Authors in this APJCE special issue have given attention to a number of areas that present as challenges. The area of negative and neglected research findings are highlighted and the reexamining the nature of the relationship between the student and workplace supervisor has been discussed. A model of enabling transformative learning is presented and an investigation of the influence of WIL experiences on undergraduate student study direction choices has been reported. Other areas in need of further research attention are also discussed.

year: 2015

title: Hoea Te Waka ki Uta: Critical Kaupapa Māori Research and Mormon Studies Moving Forward

authors: Simon, Hemopereki

abstract: The following is a reflective commentary on the place of Critical Indigenous Studies, with a focus on Kaupapa Māori Research, within Mormon Studies. Specifically, the piece explores the following questions: What does Kaupapa Māori Research look like when engaging in Mormon Studies? What positionality needs to be taken by Kaupapa Māori researchers and Critical Indigenous scholars when engaging in Mormon Studies? What are the main areas Critical Indigenous scholars and Kaupapa Māori scholars should engage when tackling issues around Mormonism? These questions are important in light of the growing importance of the cultural renaissance in Te Ao Māori and the rise of Kaupapa Māori Research.

text: Hoea Te Waka ki Uta: Critical Kaupapa Māori Research and Mormon Studies Moving Forward The following is a reflective commentary on the place of Critical Indigenous Studies, with a focus on Kaupapa Māori Research, within Mormon Studies. Specifically, the piece explores the following questions: What does Kaupapa Māori Research look like when engaging in Mormon Studies? What positionality needs to be taken by Kaupapa Māori researchers and Critical Indigenous scholars when engaging in Mormon Studies? What are the main areas Critical Indigenous scholars and Kaupapa Māori scholars should engage when tackling issues around Mormonism? These questions are important in light of the growing importance of the cultural renaissance in Te Ao Māori and the rise of Kaupapa Māori Research.

year: 2021