title: Partial maps with domain and range: extending Schein's representation

authors: Jackson, Marcel

subjects: closure semigroup

abstract: The semigroup of all partial maps on a set under the operation of composition admits a number of operations relating to the domain and range of a partial map. Of particular interest are the operations R and L returning the identity on the domain of a map and on the range of a map respectively. Schein [25] gave an axiomatic characterisation of the semigroups with R and L representable as systems of partial maps; the class is a finitely axiomatisable quasivariety closely related to ample semigroups (which were introduced—as type A semigroups—by Fountain, [7]). We provide an account of Schein's result (which until now appears only in Russian) and extend Schein's method to include the binary operations of intersection, of greatest common range restriction, and some unary operations relating to the set of fixed points of a partial map. Unlike the case of semigroups with R and L, a number of the possibilities can be equationally axiomatised.

text: Partial maps with domain and range: extending Schein's representation The semigroup of all partial maps on a set under the operation of composition admits a number of operations relating to the domain and range of a partial map. Of particular interest are the operations R and L returning the identity on the domain of a map and on the range of a map respectively. Schein [25] gave an axiomatic characterisation of the semigroups with R and L representable as systems of partial maps; the class is a finitely axiomatisable quasivariety closely related to ample semigroups (which were introduced—as type A semigroups—by Fountain, [7]). We provide an account of Schein's result (which until now appears only in Russian) and extend Schein's method to include the binary operations of intersection, of greatest common range restriction, and some unary operations relating to the set of fixed points of a partial map. Unlike the case of semigroups with R and L, a number of the possibilities can be equationally axiomatised.

year: 2009

title: Transferable semi-autonomous architecture for vehicles operating in corridor crop environments

authors: Tobias, Jonathan Isaac

subjects: Semi-autonomous

abstract: The role of autonomous vehicles (AVs) in assisting people is recognised and, therefore, is in constant development in numerous fields. Specifically, AV’s ability to alleviate global stressors, including an increased potential for food shortages and the decline in workers for potentially laborious work. An area where AVs developments are particularly prevalent is in agriculture. However, the few AVs being used in agriculture are often custom built for specific purposes and require large development time as a result. This thesis aims to build and evaluate a versatile architecture that can be transferred to any agricultural vehicle, thus decreasing the development time.

This thesis presents a novel architecture known as a semi-autonomous architecture (SAA). The research involved investigating and incorporating specific sensors, and also developing a common software module to perform the localisation, navigation and mapping particularly suited for corridor crop agricultural environment. This architecture was integrated and implemented on a Yamaha golf cart, infusing it with purposely positioned sensors and supportive electronics to allow a Robotic Operating System (ROS) framework to gather information and control the vehicle. As the architecture is modular in nature, it can be transferred to different customised platforms.

To determine the efficacy of the SAA, the platform went through a field trial and simulations to test the fundamentals of an agricultural AV. This meant investigating the SAA’s ability to map, plan paths, avoid obstacles and maintain a specific distance from a row. The evaluation demonstrated that both ’RTAB-Map’ and ’Gmapping’ could produce accurate maps of a vineyard. Additionally, grid-based planners, such as Dijkstra and A*, performed better than a sample-based planner bias-IRRT*. Regarding obstacle avoidance, the SAA required a greater range of sensors to detect small and oddly shaped objects that could be found in a vineyard. The SAA maintained within 5mm of the specified distance when aiming to follow the row. The results from these experiments demonstrated the SAA’s ability to successfully transform a Yamaha golf cart into a semi-autonomous agricultural vehicle.

text: Transferable semi-autonomous architecture for vehicles operating in corridor crop environments The role of autonomous vehicles (AVs) in assisting people is recognised and, therefore, is in constant development in numerous fields. Specifically, AV’s ability to alleviate global stressors, including an increased potential for food shortages and the decline in workers for potentially laborious work. An area where AVs developments are particularly prevalent is in agriculture. However, the few AVs being used in agriculture are often custom built for specific purposes and require large development time as a result. This thesis aims to build and evaluate a versatile architecture that can be transferred to any agricultural vehicle, thus decreasing the development time.

This thesis presents a novel architecture known as a semi-autonomous architecture (SAA). The research involved investigating and incorporating specific sensors, and also developing a common software module to perform the localisation, navigation and mapping particularly suited for corridor crop agricultural environment. This architecture was integrated and implemented on a Yamaha golf cart, infusing it with purposely positioned sensors and supportive electronics to allow a Robotic Operating System (ROS) framework to gather information and control the vehicle. As the architecture is modular in nature, it can be transferred to different customised platforms.

To determine the efficacy of the SAA, the platform went through a field trial and simulations to test the fundamentals of an agricultural AV. This meant investigating the SAA’s ability to map, plan paths, avoid obstacles and maintain a specific distance from a row. The evaluation demonstrated that both ’RTAB-Map’ and ’Gmapping’ could produce accurate maps of a vineyard. Additionally, grid-based planners, such as Dijkstra and A*, performed better than a sample-based planner bias-IRRT*. Regarding obstacle avoidance, the SAA required a greater range of sensors to detect small and oddly shaped objects that could be found in a vineyard. The SAA maintained within 5mm of the specified distance when aiming to follow the row. The results from these experiments demonstrated the SAA’s ability to successfully transform a Yamaha golf cart into a semi-autonomous agricultural vehicle.

year: 2022

title: Ahumai

authors: Temara, Pou

subjects: Pātere

abstract: E tika ana kia punarua te wānanga i ēnei pātere e rua nā te mea he mārama te kite iho o whatu he ōrite ētahi o ngā rārangi kupu, ngā whakaaro me ngā kareāroto ki te pātere a Ahumai. Ahakoa kāore i te takoto te ingoa o te kaitito i tēnei pātere, nā te ōrite o ētahi o ngā kupu, e taea te whakapae, nā te ringa kotahi ēnei pātere i waituhi? Kai roto hoki i te pātere nei e takaoto ana ngā rohe o Raukawa pērā i Wharepūhunga, me ngā tangata whai mana o tērā iwi pērā i a Tīkao. Hei taituarā ka hahua ake anō te kōrero a Turanga Te Mauparaoa ki te tata o te rohe o te iwi nāna te waiata nei, ki tōna rohe. Kāore te Māori e kī ‘nō tua ake nei tēnei pātere’ mēnā he tawhiti atu te iwi i tōna. Nō reira, ki taku wānanga, ehara tēnei pātere nō ngā iwi o Taranaki. He tawhiti rawa a Taranaki i Murupara. Hāunga a Raukawa, koia te iwi kai ‘tua ake nei’.

E tuku ana ahau i taku ihu kia puta. Ki te tapahia mai, e pai ana. E kī ana hoki au, ko te mea poto te titonga tuatahi, ko te mea roa te titonga o muri mai. He ariā te mea tuatahi nō te mea tuarua.

text: Ahumai E tika ana kia punarua te wānanga i ēnei pātere e rua nā te mea he mārama te kite iho o whatu he ōrite ētahi o ngā rārangi kupu, ngā whakaaro me ngā kareāroto ki te pātere a Ahumai. Ahakoa kāore i te takoto te ingoa o te kaitito i tēnei pātere, nā te ōrite o ētahi o ngā kupu, e taea te whakapae, nā te ringa kotahi ēnei pātere i waituhi? Kai roto hoki i te pātere nei e takaoto ana ngā rohe o Raukawa pērā i Wharepūhunga, me ngā tangata whai mana o tērā iwi pērā i a Tīkao. Hei taituarā ka hahua ake anō te kōrero a Turanga Te Mauparaoa ki te tata o te rohe o te iwi nāna te waiata nei, ki tōna rohe. Kāore te Māori e kī ‘nō tua ake nei tēnei pātere’ mēnā he tawhiti atu te iwi i tōna. Nō reira, ki taku wānanga, ehara tēnei pātere nō ngā iwi o Taranaki. He tawhiti rawa a Taranaki i Murupara. Hāunga a Raukawa, koia te iwi kai ‘tua ake nei’.

E tuku ana ahau i taku ihu kia puta. Ki te tapahia mai, e pai ana. E kī ana hoki au, ko te mea poto te titonga tuatahi, ko te mea roa te titonga o muri mai. He ariā te mea tuatahi nō te mea tuarua.

year: 2017