Development of an Underground Mine Scout Robot

<p>Despite increased safety and improved technology in the mining industry, fatal disasters still occur. Robots have the potential to be an invaluable resource for search and rescue teams to scout dangerous or difficult situations. Existing underground mine search and rescue robots have demonstrated limited success. Identified through literature, the two primary concerns are unreliable locomotion systems and a lack of underground mine environment consideration. HADES, an underground mine disaster scout, addresses these issues with a unique chassis and novel locomotion. A system level design is carried out, addressing the difficulties of underground mine environments. To operate in an explosive atmosphere, a purge and pressurisation system is applied to a fibre glass chassis, with intrinsic safety incorporated into the sensor design. To prevent dust, dirt and water damaging the electronics, ingress protection is applied through sealing. The chassis is invertible, with a low centre of gravity and a roll-axis pivot. This chassis design, in combination with spoked-wheels allows traversal of the debris and rubble of a disaster site. Electrochemical gas sensors are incorporated, along with RGB-D cameras, two-way audio and various other environment sensors. A communication system combining a tether and mesh network is designed, with wireless nodes to increase wireless range and reliability. Electronic hardware and software control are implemented to produce an operational scout robot. HADES is 0.7 × 0.6 × 0.4 m, with a sealed IP65 chassis. The locomotion system is robust and effective, able to traverse most debris and rubble, as tested on the university grounds and at a clean landfill. Bottoming out is the only problem encountered, but can be avoided by approaching obstacles correctly. The motor drive system is able to drive HADES at walking speed (1.4 m/s) and it provides more torque than traction allows. Six Lithium-Polymer batteries enable 2 hours 28 minutes of continuous operation. At 20 kg and ~$7000, HADES is a portable, inexpensive scout robot for underground mine disasters.</p>

Development of an Underground Mine Scout Robot

<p>Despite increased safety and improved technology in the mining industry, fatal disasters still occur. Robots have the potential to be an invaluable resource for search and rescue teams to scout dangerous or difficult situations. Existing underground mine search and rescue robots have demonstrated limited success. Identified through literature, the two primary concerns are unreliable locomotion systems and a lack of underground mine environment consideration. HADES, an underground mine disaster scout, addresses these issues with a unique chassis and novel locomotion. A system level design is carried out, addressing the difficulties of underground mine environments. To operate in an explosive atmosphere, a purge and pressurisation system is applied to a fibre glass chassis, with intrinsic safety incorporated into the sensor design. To prevent dust, dirt and water damaging the electronics, ingress protection is applied through sealing. The chassis is invertible, with a low centre of gravity and a roll-axis pivot. This chassis design, in combination with spoked-wheels allows traversal of the debris and rubble of a disaster site. Electrochemical gas sensors are incorporated, along with RGB-D cameras, two-way audio and various other environment sensors. A communication system combining a tether and mesh network is designed, with wireless nodes to increase wireless range and reliability. Electronic hardware and software control are implemented to produce an operational scout robot. HADES is 0.7 × 0.6 × 0.4 m, with a sealed IP65 chassis. The locomotion system is robust and effective, able to traverse most debris and rubble, as tested on the university grounds and at a clean landfill. Bottoming out is the only problem encountered, but can be avoided by approaching obstacles correctly. The motor drive system is able to drive HADES at walking speed (1.4 m/s) and it provides more torque than traction allows. Six Lithium-Polymer batteries enable 2 hours 28 minutes of continuous operation. At 20 kg and ~$7000, HADES is a portable, inexpensive scout robot for underground mine disasters.</p>

Stochastic Method to Predict Effects of Roll Grinding Deviations on Sheet Flatness in Cold Rolling

Industrial measurements of the diameter profiles of work-rolls used in cold sheet rolling are applied with a stochastic roll-stack model to better understand how residual error from the roll grinding process affects the rolled sheet flatness quality. Roll diameter measurements taken via a non-contact, optical device on new, warm, and worn work-rolls show that the diameter deviations vary along the roll lengths, across roll samples, and at different operational states, suggesting a multi-dimensional random field problem. Studies are conducted for a 4-high rolling mill with 301 stainless steel sheet to investigate the reliability in achieving target flatness considering the work-roll diameter random field. Also investigated is the sensitivity of the flatness reliability to roll diameter deviations at different locations along the roll lengths, and for the three operational states (newly machined, warm, and worn following several passes). The results lead to several key findings. Foremost, it is shown that an assumption of statistical independence among the residual grinding errors at different roll axis locations is improper. Further, it is demonstrated that, for the measured grinding error correlation patterns, the roll diameter deviations external to the roll/sheet contact region play an important role in contributing to flatness defects within the sheet, and that these influences vary according to the roll operational state (new, warm, worn). The presented stochastic model and applied measurement data thus provide for a new understanding into how roll grinding performance influences dimensional quality in the sheet rolling process.

Dragondrop: a novel passive mechanism for aerial righting in the dragonfly

Dragonflies perform dramatic aerial manoeuvres when chasing targets but glide for periods during cruising flights. This makes dragonflies a great system to explore the role of passive stabilizing mechanisms that do not compromise manoeuvrability. We challenged dragonflies by dropping them from selected inverted attitudes and collected 6-degrees-of-freedom aerial recovery kinematics via custom motion capture techniques. From these kinematic data, we performed rigid-body inverse dynamics to reconstruct the forces and torques involved in righting behaviour. We found that inverted dragonflies typically recover themselves with the shortest rotation from the initial body inclination. Additionally, they exhibited a strong tendency to pitch-up with their head leading out of the manoeuvre, despite the lower moment of inertia in the roll axis. Surprisingly, anaesthetized dragonflies could also complete aerial righting reliably. Such passive righting disappeared in recently dead dragonflies but could be partially recovered by waxing their wings to the anaesthetised posture. Our kinematics data, inverse dynamics model and wind-tunnel experiments suggest that the dragonfly's long abdomen and wing posture generate a rotational tendency and passive attitude recovery mechanism during falling. This work demonstrates an aerodynamically stable body configuration in a flying insect and raises new questions in sensorimotor control for small flying systems.

Probabilistic optimization of engine mount to enhance vibration characteristics using first-order reliability-based target cascading

Uncertainties cause tremendous failures, especially in large-scale system design, because they are accumulated from each of the subsystems. Analytical target cascading is a multidisciplinary design optimization method that enables the achievement of a concurrent and consistent design for large-scale systems. To address the uncertainties in analytical target cascading efficiently, we propose reliability-based target cascading combined with first-order reliability assessment algorithms, such as mean-value first-order second moment, performance measure analysis, and reliability index analysis. The effectiveness of the implemented algorithms was first demonstrated via a mathematical programming problem and then a practical engineering problem, involving automotive engine mount optimization, for minimizing both the difference between torque roll axis and elastic roll axis and the vibration transmissibility under mode purity requirements. The optimized design solutions are compared among three reliability assessment algorithms of reliability-based target cascading, and the uncertainty propagation with Gaussian distributions was quantified and verified. The probabilistic design results indicate that the first-order reliability-based target cascading methods successfully identify more reliable and conservative optimized solutions than analytical target cascading.

Collision of tall vehicles due to lean

Tall vehicles like trucks and buses tend to sway about roll axis when they encounter an uneven road surface that interacts differently with different wheels. The extent of this sway is significantly more for tall vehicles so much so, they lean over a certain distance to the side. When two tall vehicles move on an uneven road adjacent to each other, this lean-over distance should be considered to steer the vehicle to avoid any collision. This paper presents this scenario and also discusses a method that relates the lean-over distance to road geometry.

Seven Degrees-of-Freedom Model for the Roll Stabilization of Unstable Ships

As demonstrated by the 2014 MV Sewol incident, the prevention of top heavy ship capsize is necessary to protect life and property aboard a ship. The goal of this paper is to prevent the capsize of ships, which lack a restoring torque about the roll axis, by using a feedback-controlled pendulum actuator. A seven degrees-of-freedom (7DOF) model is developed for a ship equipped with a pendulum actuator. The model is used to conduct parameter analyses on the pendulum length, pendulum mast height, pendulum mass, ship center of mass (COM) height, and the pendulum controller's proportional feedback gain. The results of these analyses are depicted via time responses and phase plots. Key points for designing a pendulum actuator summarize simulation results, stating that the pendulum mass should be 3–7% of the total ship mass, and the pendulum moment of inertia should be 0.5–1.0 times the roll moment of inertia of the ship.