Admittance Control for Robotic Loading: Design and Experiments with a 1-Tonne Loader and a 14-Tonne LHD

This paper describes the design, tuning, and extensive field testing of an admittance-based Autonomous Loading Controller (ALC) for robotic excavation. Several iterations of the ALC were tuned and tested in fragmented rock piles—similar to those found in operating mines—by using both a robotic 1-tonne capacity Kubota R520S diesel-hydraulic surface loader and a 14-tonne capacity Atlas Copco ST14 underground load-haul-dump (LHD) machine. On the R520S loader, the ALC increased payload by 18 % with greater consistency, although with more energy expended and longer dig times when compared with digging at maximum actuator velocity. On the ST14 LHD, the ALC took 61 % less time to load 39 % more payload when compared to a single manual operator. The manual operator made 28 dig attempts by using three different digging strategies, and had one failed dig. The tuned ALC made 26 dig attempts at 10 and 11 MN target force levels. All 10 11 MN digs succeeded while 6 of the 16 10 MN digs failed. The results presented in this paper suggest that the admittance-based ALC is more productive and consistent than manual operators, but that care should be taken when detecting entry into the muck pile

A case study on a design-informed developmental evaluation

Developmental evaluation (DE) is an evaluation approach that aims to support the development of an innovation (Patton, 1994, 2011). This aim is achieved through supporting clients’ information needs through evaluative inquiry as they work to develop and refine the innovation. While core concepts and principles are beginning to be articulated and refined, challenges remain as to how to focus a developmental evaluation beyond those knowledge frameworks most immediate to clients to support innovation development. Anchoring a DE in knowledge frameworks other than those of the clients might direct attention to issues not yet obvious to clients, but which might further the goal of supporting innovation development if attended to. Drawing concepts and practices from the field of design may be one avenue with which to inform developmental evaluation in achieving its aim. Through a case study methodology, this research seeks to understand the nuances of operationalizing the guiding principles of DE as well as to investigate the utility, feasibility, and consequences of integrating design concepts and practices into developmental evaluation (design-informed developmental evaluation, “DI-DE”). It does so by documenting the efforts of a design-informed developmental evaluator and a task force of educators and researchers in a Faculty of Education as they work to develop a graduate-level education program. A systematic review into those purposeful efforts made to introduce DI-DE thinking into task force deliberations, and an analysis into the responses and consequences of those efforts shed light on what it had meant to practice DI-DE. As a whole, this research on evaluation is intended to further contemporary thinking about the closely coupled relationship between program development and evaluation in complex and dynamic environments.