Reducing digger energy consumption by improving the walking mechanism

To evaluate the energy to move the excavator body, we calculated the effort involved in the hydraulic cylinders of the walking mechanism. Unlike man, "pacing" the excavator is on a "drawing", in which the housing pulls the excavator walking mechanism in the direction of the reference points. As a result, the kinematic and dynamic study of the process of pacing is reduced to the analysis of speeds and loads for the simplest of mechanisms, known since ancient times as the slider-crank mechanism. Analysis of the motion of this mechanism can be carried out by conventional (calculated for one position) or by modern analytical methods. Modern methods of analytical studies of the mechanisms permit a computer calculation of the full cycle of movement of the excavator in a single step and to evaluate the stresses produced in the hydraulic cylinders. A variety of design solutions based on different positions of the connecting joints is recorded during the test set kinematics and, accordingly, an amount in the results is obtained. Power movement by one step excavator is theoretically estimated as the amount of work the forces acting on the mechanism during this step undertake. A design that corresponds to the minimum energy consumption should be considered optimal for this type of walking mechanism. The authors of this paper analyzed the performing over thirty different types of mechanisms of pacing. Recommendations for optimizing their designs are formulated for each of these, which not only reduces the power consumption excavator, but also reduces its price. © 2014 WIT Press

Learning Excavation of Rigid Objects with Offline Reinforcement Learning

Autonomous excavation is a challenging task. The unknown contact dynamics between the excavator bucket and the terrain could easily result in large contact forces and jamming problems during excavation. Traditional model-based methods struggle to handle such problems due to complex dynamic modeling. In this paper, we formulate the excavation skills with three novel manipulation primitives. We propose to learn the manipulation primitives with offline reinforcement learning (RL) to avoid large amounts of online robot interactions. The proposed method can learn efficient penetration skills from sub-optimal demonstrations, which contain sub-trajectories that can be ``stitched" together to formulate an optimal trajectory without causing jamming. We evaluate the proposed method with extensive experiments on excavating a variety of rigid objects and demonstrate that the learned policy outperforms the demonstrations. We also show that the learned policy can quickly adapt to unseen and challenging fragmented rocks with online fine-tuning.Comment: Submitted to IROS 202

Preserving the impossible: conservation of soft-sediment hominin footprint sites and strategies for three-dimensional digital data capture.

Human footprints provide some of the most publically emotive and tangible evidence of our ancestors. To the scientific community they provide evidence of stature, presence, behaviour and in the case of early hominins potential evidence with respect to the evolution of gait. While rare in the geological record the number of footprint sites has increased in recent years along with the analytical tools available for their study. Many of these sites are at risk from rapid erosion, including the Ileret footprints in northern Kenya which are second only in age to those at Laetoli (Tanzania). Unlithified, soft-sediment footprint sites such these pose a significant geoconservation challenge. In the first part of this paper conservation and preservation options are explored leading to the conclusion that to 'record and digitally rescue' provides the only viable approach. Key to such strategies is the increasing availability of three-dimensional data capture either via optical laser scanning and/or digital photogrammetry. Within the discipline there is a developing schism between those that favour one approach over the other and a requirement from geoconservationists and the scientific community for some form of objective appraisal of these alternatives is necessary. Consequently in the second part of this paper we evaluate these alternative approaches and the role they can play in a 'record and digitally rescue' conservation strategy. Using modern footprint data, digital models created via optical laser scanning are compared to those generated by state-of-the-art photogrammetry. Both methods give comparable although subtly different results. This data is evaluated alongside a review of field deployment issues to provide guidance to the community with respect to the factors which need to be considered in digital conservation of human/hominin footprints

Combined Sampling and Optimization Based Planning for Legged-Wheeled Robots

Planning for legged-wheeled machines is typically done using trajectory optimization because of many degrees of freedom, thus rendering legged-wheeled planners prone to falling prey to bad local minima. We present a combined sampling and optimization-based planning approach that can cope with challenging terrain. The sampling-based stage computes whole-body configurations and contact schedule, which speeds up the optimization convergence. The optimization-based stage ensures that all the system constraints, such as non-holonomic rolling constraints, are satisfied. The evaluations show the importance of good initial guesses for optimization. Furthermore, they suggest that terrain/collision (avoidance) constraints are more challenging than the robot model's constraints. Lastly, we extend the optimization to handle general terrain representations in the form of elevation maps

Volume 1 – Symposium

We are pleased to present the conference proceedings for the 12th edition of the International Fluid Power Conference (IFK). The IFK is one of the world’s most significant scientific conferences on fluid power control technology and systems. It offers a common platform for the presentation and discussion of trends and innovations to manufacturers, users and scientists. The Chair of Fluid-Mechatronic Systems at the TU Dresden is organizing and hosting the IFK for the sixth time. Supporting hosts are the Fluid Power Association of the German Engineering Federation (VDMA), Dresdner Verein zur Förderung der Fluidtechnik e. V. (DVF) and GWT-TUD GmbH. The organization and the conference location alternates every two years between the Chair of Fluid-Mechatronic Systems in Dresden and the Institute for Fluid Power Drives and Systems in Aachen. The symposium on the first day is dedicated to presentations focused on methodology and fundamental research. The two following conference days offer a wide variety of application and technology orientated papers about the latest state of the art in fluid power. It is this combination that makes the IFK a unique and excellent forum for the exchange of academic research and industrial application experience. A simultaneously ongoing exhibition offers the possibility to get product information and to have individual talks with manufacturers. The theme of the 12th IFK is “Fluid Power – Future Technology”, covering topics that enable the development of 5G-ready, cost-efficient and demand-driven structures, as well as individual decentralized drives. Another topic is the real-time data exchange that allows the application of numerous predictive maintenance strategies, which will significantly increase the availability of fluid power systems and their elements and ensure their improved lifetime performance. We create an atmosphere for casual exchange by offering a vast frame and cultural program. This includes a get-together, a conference banquet, laboratory festivities and some physical activities such as jogging in Dresden’s old town.:Group A: Materials Group B: System design & integration Group C: Novel system solutions Group D: Additive manufacturing Group E: Components Group F: Intelligent control Group G: Fluids Group H | K: Pumps Group I | L: Mobile applications Group J: Fundamental

Computational dynamics and virtual dragline simulation for extended rope service life

The dragline machinery is one of the largest equipment for stripping overburden materials in surface mining operations. Its effectiveness requires rigorous kinematic and dynamic analyses. Current dragline research studies are limited in computational dynamic modeling because they eliminate important structural components from the front-end assembly. Thus, the derived kinematic, dynamic and stress intensity models fail to capture the true response of the dragline under full operating cycle conditions. This research study advances a new and robust computational dynamic model of the dragline front-end assembly using Kane\u27s method. The model is a 3-DOF dynamic model that describes the spatial kinematics and dynamics of the dragline front-end assembly during digging and swinging. A virtual simulator, for a Marion 7800 dragline, is built and used for analyzing the mass and inertia properties of the front-end components. The models accurately predict the kinematics, dynamics and stress intensity profiles of the front-end assembly. The results showed that the maximum drag force is 1.375 MN, which is within the maximum allowable load of the machine. The maximum cutting resistance of 412.31 KN occurs 5 seconds into digging and the maximum hoist torque of 917. 87 KN occurs 10 seconds into swinging. Stress analyses are carried out on wire ropes using ANSYS Workbench under static and dynamic loading. The FEA results showed that significant stresses develop in the contact areas between the wires, with a maximum von Mises stress equivalent to 7800 MPa. This research study is a pioneering effort toward developing a comprehensive multibody dynamic model of the dragline machinery. The main novelty is incorporating the boom point-sheave, drag-chain and sliding effect of the bucket, excluded from previous research studies, to obtain computationally dynamic efficient models for load predictions --Abstract, page iii

Middle and Late Bronze Age settlement on the South Downs: the case study of Black Patch

By integrating the corpus of existing knowledge with new information gained by applying geo-archaeological techniques as well as more traditional techniques to fresh archaeological investigations at Black Patch and elsewhere, the aims of the research are to look at the economy, social organization and ritual behaviour of life in the Middle and Late Bronze Age on the South Downs in the light of modern archaeological theory to consider the questions ‘Why were these areas chosen for settlement?’, ‘What caused their abandonment?’ and ‘What can we learn about the life of the people associated with the settlements?’. The combination of field walking, field survey and soil sampling has shown the presence of a Neolithic flint spread, woodland clearance and agriculture before and during the period of site settlement at Black Patch. The positioning of the Hut platforms and enclosures across existing lynchets, the modification of the existing field system, the establishment of a new one and the adoption of more intensive farming techniques (manuring, weeding and crop location and rotation) would imply a change of social order and the adoption of a sedentary lifestyle for some. The existence of centrally placed hearths in huts found at Black Patch brings into doubt the existing day/night life/death metaphor currently commonly used for this period. Structured deposition points to a society concerned with agricultural fertility. The abandonment of Black Patch identified by Drewett and the dearth of later dated artefacts, at about the same time as the abandonment of the only other positively identified Deverel-Rimbury site in the immediate area, Itford Hill, suggests another change of social order, with livestock becoming more important as the Downland area around Black Patch appears then to be used only by nomadic herders. Areas to the west of the River Ouse which had been settled earlier developed more complicated specialist production sites. These have yet to be found east of the River Ous

Volume 3 – Conference

We are pleased to present the conference proceedings for the 12th edition of the International Fluid Power Conference (IFK). The IFK is one of the world’s most significant scientific conferences on fluid power control technology and systems. It offers a common platform for the presentation and discussion of trends and innovations to manufacturers, users and scientists. The Chair of Fluid-Mechatronic Systems at the TU Dresden is organizing and hosting the IFK for the sixth time. Supporting hosts are the Fluid Power Association of the German Engineering Federation (VDMA), Dresdner Verein zur Förderung der Fluidtechnik e. V. (DVF) and GWT-TUD GmbH. The organization and the conference location alternates every two years between the Chair of Fluid-Mechatronic Systems in Dresden and the Institute for Fluid Power Drives and Systems in Aachen. The symposium on the first day is dedicated to presentations focused on methodology and fundamental research. The two following conference days offer a wide variety of application and technology orientated papers about the latest state of the art in fluid power. It is this combination that makes the IFK a unique and excellent forum for the exchange of academic research and industrial application experience. A simultaneously ongoing exhibition offers the possibility to get product information and to have individual talks with manufacturers. The theme of the 12th IFK is “Fluid Power – Future Technology”, covering topics that enable the development of 5G-ready, cost-efficient and demand-driven structures, as well as individual decentralized drives. Another topic is the real-time data exchange that allows the application of numerous predictive maintenance strategies, which will significantly increase the availability of fluid power systems and their elements and ensure their improved lifetime performance. We create an atmosphere for casual exchange by offering a vast frame and cultural program. This includes a get-together, a conference banquet, laboratory festivities and some physical activities such as jogging in Dresden’s old town.:Group 8: Pneumatics Group 9 | 11: Mobile applications Group 10: Special domains Group 12: Novel system architectures Group 13 | 15: Actuators & sensors Group 14: Safety & reliabilit