title: The Barracuda: An investigation of a novel cane pruning technology for avoiding wires in structured vineyard environments

authors: Harvey, Scott

subjects: Robotic

abstract: The viticulture industry, among many others, is trying to improve their product quality whilst facing labour supply challenges and increasing labour costs. The Maaratech research group has been developing human assist technology and an autonomous, prototype grape vine pruning machine to alleviate these issues. The machine is an arched “straddle” platform, containing a camera array, PC, UR5 manipulator, and end-effector. The canes of the grapevine are wrapped around guide wires, making it very difficult for cuts to be made – whether by human or robot. This thesis presents the process of developing and testing a novel technology called the Barracuda, to enable cuts to be made where the wire interferes with a cut. The wire also puts high accuracy requirements on the vision system and manipulator movements if a secondary mechanism was used to separate the wire and cane. The Barracuda was developed as an end effector to alleviate these issues by allowing passive wire separation from the cane. It works by exploiting the diameter difference between the smaller wire, and larger canes. The wire falls into slots, evading the blade, while the cane is cut.

Two Barracuda configurations were tested by making cuts on canes wrapped around the guide wire. Config 1 was a single row of teeth, with larger recesses, flat teeth and a blade-guiding chamfer. Config 2 used two rows of teeth either side of smaller recesses and included rounded teeth tips. The components are CNC machined or laser cut. Results showed for both configurations, the 0° position was most effective. The 0° position is where the wire was below the cane, relative to the handpiece. In this position, Config 1 was effective 40.7% of the time, and config 2, 94.5% of the time. Damage to the wire was caused 8.9% of the time for config 1, and config 2 just 2.6% of the time. Both blades received the same rate of blade damage, however the damage was visibly more significant on config 1. From these results, config 2 was the preferred design, but integrating a chamfer from config 1 should reduce blade damage further.

It also benefits human assist goals. By allowing cuts on the wire, pruners are able to make cuts quickly and easily with Barracuda-modified secateurs or loppers, removing the need to separate the cane from the wire. The design works around the environment, increases the number of points available for decision making, and allows some inaccuracy in the rest of the robotic system by offering passive wire avoidance with the teeth. The performance of the Barracuda in cut situations involving a wire proved it valuable for integration with current manual pruning methods, and as a cornerstone for robotic pruning development, providing further opportunities for the greater system.

text: The Barracuda: An investigation of a novel cane pruning technology for avoiding wires in structured vineyard environments The viticulture industry, among many others, is trying to improve their product quality whilst facing labour supply challenges and increasing labour costs. The Maaratech research group has been developing human assist technology and an autonomous, prototype grape vine pruning machine to alleviate these issues. The machine is an arched “straddle” platform, containing a camera array, PC, UR5 manipulator, and end-effector. The canes of the grapevine are wrapped around guide wires, making it very difficult for cuts to be made – whether by human or robot. This thesis presents the process of developing and testing a novel technology called the Barracuda, to enable cuts to be made where the wire interferes with a cut. The wire also puts high accuracy requirements on the vision system and manipulator movements if a secondary mechanism was used to separate the wire and cane. The Barracuda was developed as an end effector to alleviate these issues by allowing passive wire separation from the cane. It works by exploiting the diameter difference between the smaller wire, and larger canes. The wire falls into slots, evading the blade, while the cane is cut.

Two Barracuda configurations were tested by making cuts on canes wrapped around the guide wire. Config 1 was a single row of teeth, with larger recesses, flat teeth and a blade-guiding chamfer. Config 2 used two rows of teeth either side of smaller recesses and included rounded teeth tips. The components are CNC machined or laser cut. Results showed for both configurations, the 0° position was most effective. The 0° position is where the wire was below the cane, relative to the handpiece. In this position, Config 1 was effective 40.7% of the time, and config 2, 94.5% of the time. Damage to the wire was caused 8.9% of the time for config 1, and config 2 just 2.6% of the time. Both blades received the same rate of blade damage, however the damage was visibly more significant on config 1. From these results, config 2 was the preferred design, but integrating a chamfer from config 1 should reduce blade damage further.

It also benefits human assist goals. By allowing cuts on the wire, pruners are able to make cuts quickly and easily with Barracuda-modified secateurs or loppers, removing the need to separate the cane from the wire. The design works around the environment, increases the number of points available for decision making, and allows some inaccuracy in the rest of the robotic system by offering passive wire avoidance with the teeth. The performance of the Barracuda in cut situations involving a wire proved it valuable for integration with current manual pruning methods, and as a cornerstone for robotic pruning development, providing further opportunities for the greater system.

year: 2022

title: Location or hukou: What most limits fertility of urban women in China?

authors: Liang, Yun

subjects: Social Sciences

abstract: China's fertility rate is below replacement level. The government is attempting to increase this rate by relaxing the one‐child policy. China faces a possible tradeoff because further urbanization is needed to raise incomes but may reduce future fertility. We decompose China's rural–urban fertility gaps using both de facto and de jure criteria for defining the urban population. The fertility‐depressing effects of holding urban hukou are more than three times larger than effects of urban residence. Less of the rural–urban fertility gap by hukou status is due to differences in characteristics than is the case for the fertility gap by place of residence.

text: Location or hukou: What most limits fertility of urban women in China? China's fertility rate is below replacement level. The government is attempting to increase this rate by relaxing the one‐child policy. China faces a possible tradeoff because further urbanization is needed to raise incomes but may reduce future fertility. We decompose China's rural–urban fertility gaps using both de facto and de jure criteria for defining the urban population. The fertility‐depressing effects of holding urban hukou are more than three times larger than effects of urban residence. Less of the rural–urban fertility gap by hukou status is due to differences in characteristics than is the case for the fertility gap by place of residence.

year: 2017

title: Māori and indigenous views on R and R: Resistance and Resilience

authors: Penehira, Mera

subjects: resilience

abstract: This article explores the development of Mäori and Indigenous frameworks of resilience, considering the impact of engaging with largely State- led notions of resilience on Mäori development. We highlight the closely linked notion of resistance, asserting the necessity of a fi rm political analysis from Indigenous researchers engaged in this discourse. One of the Indigenous criticisms of resilience theories is that by defi nition they assume an acceptance of responsibility for our position as disadvantaged individuals. That is, by examining and developing theories and models of resilience we buy into the idea that this is the way it is and we need simply to get better at bouncing back and being resilient. Resistance, however, represents an approach of collective fi ght- back, exposing the inequitable distribution of power, and actively opposing negative social, political and economic infl uences. This article represents a Mäori Indigenous political response to the resilience discourse.

text: Māori and indigenous views on R and R: Resistance and Resilience This article explores the development of Mäori and Indigenous frameworks of resilience, considering the impact of engaging with largely State- led notions of resilience on Mäori development. We highlight the closely linked notion of resistance, asserting the necessity of a fi rm political analysis from Indigenous researchers engaged in this discourse. One of the Indigenous criticisms of resilience theories is that by defi nition they assume an acceptance of responsibility for our position as disadvantaged individuals. That is, by examining and developing theories and models of resilience we buy into the idea that this is the way it is and we need simply to get better at bouncing back and being resilient. Resistance, however, represents an approach of collective fi ght- back, exposing the inequitable distribution of power, and actively opposing negative social, political and economic infl uences. This article represents a Mäori Indigenous political response to the resilience discourse.

year: 2014