System Development of an Unmanned Ground Vehicle and Implementation of an Autonomous Navigation Module in a Mine Environment

There are numerous benefits to the insights gained from the exploration and exploitation of underground mines. There are also great risks and challenges involved, such as accidents that have claimed many lives. To avoid these accidents, inspections of the large mines were carried out by the miners, which is not always economically feasible and puts the safety of the inspectors at risk. Despite the progress in the development of robotic systems, autonomous navigation, localization and mapping algorithms, these environments remain particularly demanding for these systems. The successful implementation of the autonomous unmanned system will allow mine workers to autonomously determine the structural integrity of the roof and pillars through the generation of high-fidelity 3D maps. The generation of the maps will allow the miners to rapidly respond to any increasing hazards with proactive measures such as: sending workers to build/rebuild support structure to prevent accidents. The objective of this research is the development, implementation and testing of a robust unmanned ground vehicle (UGV) that will operate in mine environments for extended periods of time. To achieve this, a custom skid-steer four-wheeled UGV is designed to operate in these challenging underground mine environments. To autonomously navigate these environments, the UGV employs the use of a Light Detection and Ranging (LiDAR) and tactical grade inertial measurement unit (IMU) for the localization and mapping through a tightly-coupled LiDAR Inertial Odometry via Smoothing and Mapping framework (LIO-SAM). The autonomous navigation module was implemented based upon the Fast likelihood-based collision avoidance with an extension to human-guided navigation and a terrain traversability analysis framework. In order to successfully operate and generate high-fidelity 3D maps, the system was rigorously tested in different environments and terrain to verify its robustness. To assess the capabilities, several localization, mapping and autonomous navigation missions were carried out in a coal mine environment. These tests allowed for the verification and tuning of the system to be able to successfully autonomously navigate and generate high-fidelity maps

Firm technological responses to regulatory changes: A longitudinal study in the Le Mans Prototype racing

Despite the critical role of regulations on competition and innovation, little is known about firm responses and related effects on performance under regulatory contingencies that are permissive or restrictive. By longitudinally investigating hybrid cars competing in the Le Mans Prototype racing (LMP1), we counter-intuitively suggest that permissive regulations increase technological uncertainty and thus decrease the firms’ likelihood of shifting their technological trajectory, while restrictive regulations lead to the opposite outcome. Further, we suggest that permissive regulations favour firms that innovate their products by sequentially upgrading core and peripheral subsystems, while restrictive regulations—in the long term— favour firms upgrading them simultaneously. Implications for theory and practice are discussed

University of Maryland walking robot: A design project for undergraduate students

The design and construction required that the walking robot machine be capable of completing a number of tasks including walking in a straight line, turning to change direction, and maneuvering over an obstable such as a set of stairs. The machine consists of two sets of four telescoping legs that alternately support the entire structure. A gear-box and crank-arm assembly is connected to the leg sets to provide the power required for the translational motion of the machine. By retracting all eight legs, the robot comes to rest on a central Bigfoot support. Turning is accomplished by rotating the machine about this support. The machine can be controlled by using either a user operated remote tether or the on-board computer for the execution of control commands. Absolute encoders are attached to all motors (leg, main drive, and Bigfoot) to provide the control computer with information regarding the status of the motors (up-down motion, forward or reverse rotation). Long and short range infrared sensors provide the computer with feedback information regarding the machine's relative position to a series of stripes and reflectors. These infrared sensors simulate how the robot might sense and gain information about the environment of Mars

Multi-Sensor Based Online Attitude Estimation and Stability Measurement of Articulated Heavy Vehicles.

Articulated wheel loaders used in the construction industry are heavy vehicles and have poor stability and a high rate of accidents because of the unpredictable changes of their body posture, mass and centroid position in complex operation environments. This paper presents a novel distributed multi-sensor system for real-time attitude estimation and stability measurement of articulated wheel loaders to improve their safety and stability. Four attitude and heading reference systems (AHRS) are constructed using micro-electro-mechanical system (MEMS) sensors, and installed on the front body, rear body, rear axis and boom of an articulated wheel loader to detect its attitude. A complementary filtering algorithm is deployed for sensor data fusion in the system so that steady state margin angle (SSMA) can be measured in real time and used as the judge index of rollover stability. Experiments are conducted on a prototype wheel loader, and results show that the proposed multi-sensor system is able to detect potential unstable states of an articulated wheel loader in real-time and with high accuracy

Autonomous Ground Vehicle Prototype via Steering-, Throttle-, and Brake-by Wire Modules

This MQP furthered previous developments working towards a vision-based autonomous ground vehicle. Through modular construction and engineering, all aspects of a self-driving vehicle were retrofitted onto our 1995 golf cart in conjunction with sensors, cameras, and computational power. This year the team improved upon the existing steering system, ruggedized the braking system, and automated the accelerator input. A graduate student partnered with our MQP team and provided software for the stereoscopic vision systems, image processing, and mobile path planning. This platform is now prepared for future teams to develop software, mobile applications, and use the autonomous vehicle for various user applications

Autonomous corner modules as an enabler for new vehicle chassis solutions

Demands for new functions and refined attributes in vehicle dynamics areleading to more complex and more expensive chassis design. To overcome this, there hasbeen increasing interest in a novel chassis design that could be reused in the developmentprocess for new vehicle platforms and mainly allow functions to be regulated by software.The Autonomous Corner Module (ACM) was invented at Volvo Car Corporation (VCC) in1998. The invention is based upon actively controlled functions and distributed actuation. Themain idea is that the ACM should enable individual control of the functions of each wheel;propulsion/braking, alignment/steering and vertical wheel load. This is done by using hubmotorsand by replacing the lower control arm of a suspension with two linear actuators,allowing them to control steering and camber simultaneously. Along with activespring/damper and wheel motors, these modules are able to individually control each wheel\u27ssteering, camber, suspension and spin velocity. This provides the opportunity to replacemechanical drive, braking, steering and suspension with distributed wheel functions which, inturn, enable new vehicle architecture and design.The aim of this paper is to present the vehicle dynamic potential of the ACM solution, bydescribing its possible uses and relating them to previous research findings. Associated worksuggests chassis solutions where different fractions of the functions of the ACM capabilityhave been used to achieve benefits in vehicle dynamics. For instance, ideas on how to useactive camber control have been presented. Other studies have reported well-knownadvantages, such as, good transient yaw control from in-wheel motor propulsion and stablechassis behaviour from four-wheel steering, when affected by side wind. However, thistechnology also presents challenges. One example is how to control the relatively largeunsprung mass that occurs due to the extra weight from the in-wheel motor. The negativeinfluence from this source can be reduced by using active control of vertical forces. Theimplementation of ACM, or similar technologies, requires a well-structured hierarchy andcontrol strategy. Associated work suggests methods for chassis control, where tyre forces canbe individually distributed from a vehicle path description. The associated workpredominately indicates that the ACM introduces new opportunities and shows itself to be apromising enabler for vehicle dynamic functions

Model Predictive Control Allocation of Systems with Different Dynamics

International audienceSeveral systems are integrated in passenger cars. Some of them are just redundant systems due to safety requirements. Others, are completely different and can interact with each other as long as they are operating inside the same vehicle. Control allocation methods have been successfully implemented in advanced aircrafts to avoid conflicts, especially in the context of redundant systems. In this paper, we will rather focus on coordinating non-redundant advanced chassis systems with different dynamics. This difference in dynamics can be especially problematic when systems exhibit different communication delays. Model Predictive Control Allocation (MPCA) methods are therefore investigated in order to activate the right system at the right moment. Results show that particularly when the most effective system is saturated, another system with a different time delay can be activated few steps before saturation to instantly take over the maneuver. With good knowledge of actuator dynamics and higher computation power, MPCA methods are able to solve complex problems in severe situations

NASA Tech Briefs Index, 1977, volume 2, numbers 1-4

Announcements of new technology derived from the research and development activities of NASA are presented. Abstracts, and indexes for subject, personal author, originating center, and Tech Brief number are presented for 1977