242 research outputs found

    Extension of the Control Concept for a Mobile Overhead Manipulator to Whole-Body Impedance Control

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    At present, robots constitute a central component of contemporary factories. The application of traditional ground-based systems, however, may lead to congested floors with minimal space left for new robots or human workers. Overhead manipulators, on the other hand, aim to occupy the unutilized ceiling space, in order to manipulate the workspace located below them. The SwarmRail system is an example of such an overhead manipulator. This concept deploys mobile units driving across a passive railstructure above the ground. Additionally, equipping the mobile units with robotic arms at their bottom side enables this design to provide continuous overhead manipulation while in motion. Although a first demonstrator confirmed the functional capability of said system, the current hardware suffers from complications while traversing rail crossings. Due to uneven rails consecutive rails, said crossing points cause the robot's wheels to collide with the new rail segment it is driving towards. Additionally, the robot experiences an undesired sudden altitude change. In this thesis, we aim to implement a hierarchical whole-body impedance tracking controller for the robots employed within the SwarmRail system. Our controller combines a kinematically controlled mobile unit with the impedance-based control of a robotic arm through an admittance interface. The focus of this thesis is set on the controller's robustness against the previously mentioned external disturbances. The performance of this controller is validated inside a simulation that incorporates the aforementioned complications. Our findings suggest, that the control strategy presented in this thesis provides a foundation for the development of a controller applicable to the physical demonstrator

    Learning-based methods for planning and control of humanoid robots

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    Nowadays, humans and robots are more and more likely to coexist as time goes by. The anthropomorphic nature of humanoid robots facilitates physical human-robot interaction, and makes social human-robot interaction more natural. Moreover, it makes humanoids ideal candidates for many applications related to tasks and environments designed for humans. No matter the application, an ubiquitous requirement for the humanoid is to possess proper locomotion skills. Despite long-lasting research, humanoid locomotion is still far from being a trivial task. A common approach to address humanoid locomotion consists in decomposing its complexity by means of a model-based hierarchical control architecture. To cope with computational constraints, simplified models for the humanoid are employed in some of the architectural layers. At the same time, the redundancy of the humanoid with respect to the locomotion task as well as the closeness of such a task to human locomotion suggest a data-driven approach to learn it directly from experience. This thesis investigates the application of learning-based techniques to planning and control of humanoid locomotion. In particular, both deep reinforcement learning and deep supervised learning are considered to address humanoid locomotion tasks in a crescendo of complexity. First, we employ deep reinforcement learning to study the spontaneous emergence of balancing and push recovery strategies for the humanoid, which represent essential prerequisites for more complex locomotion tasks. Then, by making use of motion capture data collected from human subjects, we employ deep supervised learning to shape the robot walking trajectories towards an improved human-likeness. The proposed approaches are validated on real and simulated humanoid robots. Specifically, on two versions of the iCub humanoid: iCub v2.7 and iCub v3

    Energy-based control approaches in human-robot collaborative disassembly

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    ๊ธฐ๊ตฌํ•™์  ๋ฐ ๋™์  ์ œํ•œ์กฐ๊ฑด๋“ค์„ ๊ณ ๋ คํ•œ ๋ชจ๋ฐ”์ผ ๋งค๋‹ˆํ“ฐ๋ ˆ์ดํ„ฐ์˜ ์ž‘์—… ์ค‘์‹ฌ ์ „์‹  ๋™์ž‘ ์ƒ์„ฑ ์ „๋žต

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    ํ•™์œ„๋…ผ๋ฌธ(๋ฐ•์‚ฌ) -- ์„œ์šธ๋Œ€ํ•™๊ต๋Œ€ํ•™์› : ์œตํ•ฉ๊ณผํ•™๊ธฐ์ˆ ๋Œ€ํ•™์› ์œตํ•ฉ๊ณผํ•™๋ถ€(์ง€๋Šฅํ˜•์œตํ•ฉ์‹œ์Šคํ…œ์ „๊ณต), 2023. 2. ๋ฐ•์žฌํฅ.๋ชจ๋ฐ”์ผ ๋งค๋‹ˆํ“ฐ๋ ˆ์ดํ„ฐ๋Š” ๋ชจ๋ฐ”์ผ ๋กœ๋ด‡์— ์žฅ์ฐฉ๋œ ๋งค๋‹ˆํ“ฐ๋ ˆ์ดํ„ฐ์ž…๋‹ˆ๋‹ค. ๋ชจ๋ฐ”์ผ ๋งค๋‹ˆํ“ฐ๋ ˆ์ดํ„ฐ๋Š” ๊ณ ์ •ํ˜• ๋งค๋‹ˆํ“ฐ๋ ˆ์ดํ„ฐ์— ๋น„ํ•ด ๋ชจ๋ฐ”์ผ ๋กœ๋ด‡์˜ ์ด๋™์„ฑ์„ ์ œ๊ณต๋ฐ›๊ธฐ ๋•Œ๋ฌธ์— ๋‹ค์–‘ํ•˜๊ณ  ๋ณต์žกํ•œ ์ž‘์—…์„ ์ˆ˜ํ–‰ํ•  ์ˆ˜ ์žˆ์Šต๋‹ˆ๋‹ค. ๊ทธ๋Ÿฌ๋‚˜ ๋‘ ๊ฐœ์˜ ์„œ๋กœ ๋‹ค๋ฅธ ์‹œ์Šคํ…œ์„ ๊ฒฐํ•ฉํ•จ์œผ๋กœ์จ ๋ชจ๋ฐ”์ผ ๋งค๋‹ˆํ“ฐ๋ ˆ์ดํ„ฐ์˜ ์ „์‹ ์„ ๊ณ„ํšํ•˜๊ณ  ์ œ์–ดํ•  ๋•Œ ์—ฌ๋Ÿฌ ํŠน์ง•์„ ๊ณ ๋ คํ•ด์•ผ ํ•ฉ๋‹ˆ๋‹ค. ์ด๋Ÿฌํ•œ ํŠน์ง•๋“ค์€ ์—ฌ์ž์œ ๋„, ๋‘ ์‹œ์Šคํ…œ์˜ ๊ด€์„ฑ ์ฐจ์ด ๋ฐ ๋ชจ๋ฐ”์ผ ๋กœ๋ด‡์˜ ๋น„ํ™€๋กœ๋…ธ๋ฏน ์ œํ•œ ์กฐ๊ฑด ๋“ฑ์ด ์žˆ์Šต๋‹ˆ๋‹ค. ๋ณธ ๋…ผ๋ฌธ์˜ ๋ชฉ์ ์€ ๊ธฐ๊ตฌํ•™์  ๋ฐ ๋™์  ์ œํ•œ์กฐ๊ฑด๋“ค์„ ๊ณ ๋ คํ•˜์—ฌ ๋ชจ๋ฐ”์ผ ๋งค๋‹ˆํ“ฐ๋ ˆ์ดํ„ฐ์˜ ์ „์‹  ๋™์ž‘ ์ƒ์„ฑ ์ „๋žต์„ ์ œ์•ˆํ•˜๋Š” ๊ฒƒ์ž…๋‹ˆ๋‹ค. ๋จผ์ €, ๋ชจ๋ฐ”์ผ ๋งค๋‹ˆํ“ฐ๋ ˆ์ดํ„ฐ๊ฐ€ ์ดˆ๊ธฐ ์œ„์น˜์—์„œ ๋ฌธ์„ ํ†ต๊ณผํ•˜์—ฌ ๋ชฉํ‘œ ์œ„์น˜์— ๋„๋‹ฌํ•˜๊ธฐ ์œ„ํ•œ ์ „์‹  ๊ฒฝ๋กœ๋ฅผ ๊ณ„์‚ฐํ•˜๋Š” ํ”„๋ ˆ์ž„์›Œํฌ๋ฅผ ์ œ์•ˆํ•ฉ๋‹ˆ๋‹ค. ์ด ํ”„๋ ˆ์ž„์›Œํฌ๋Š” ๋กœ๋ด‡๊ณผ ๋ฌธ์— ์˜ํ•ด ์ƒ๊ธฐ๋Š” ๊ธฐ๊ตฌํ•™์  ์ œํ•œ์กฐ๊ฑด์„ ๊ณ ๋ คํ•ฉ๋‹ˆ๋‹ค. ์ œ์•ˆํ•˜๋Š” ํ”„๋ ˆ์ž„์›Œํฌ๋Š” ๋‘ ๋‹จ๊ณ„๋ฅผ ๊ฑฐ์ณ ์ „์‹ ์˜ ๊ฒฝ๋กœ๋ฅผ ์–ป์Šต๋‹ˆ๋‹ค. ์ฒซ ๋ฒˆ์งธ ๋‹จ๊ณ„์—์„œ๋Š” ๊ทธ๋ž˜ํ”„ ํƒ์ƒ‰ ์•Œ๊ณ ๋ฆฌ์ฆ˜์„ ์ด์šฉํ•˜์—ฌ ๋ชจ๋ฐ”์ผ ๋กœ๋ด‡์˜ ์ž์„ธ ๊ฒฝ๋กœ์™€ ๋ฌธ์˜ ๊ฐ๋„ ๊ฒฝ๋กœ๋ฅผ ๊ณ„์‚ฐํ•ฉ๋‹ˆ๋‹ค. ํŠนํžˆ, ๊ทธ๋ž˜ํ”„ ํƒ์ƒ‰์—์„œ area indicator๋ผ๋Š” ์ •์ˆ˜ ๋ณ€์ˆ˜๋ฅผ ์ƒํƒœ์˜ ๊ตฌ์„ฑ ์š”์†Œ๋กœ์„œ ์ •์˜ํ•˜๋Š”๋ฐ, ์ด๋Š” ๋ฌธ์— ๋Œ€ํ•œ ๋ชจ๋ฐ”์ผ ๋กœ๋ด‡์˜ ์ƒ๋Œ€์  ์œ„์น˜๋ฅผ ๋‚˜ํƒ€๋ƒ…๋‹ˆ๋‹ค. ๋‘ ๋ฒˆ์งธ ๋‹จ๊ณ„์—์„œ๋Š” ๋ชจ๋ฐ”์ผ ๋กœ๋ด‡์˜ ๊ฒฝ๋กœ์™€ ๋ฌธ์˜ ๊ฐ๋„๋ฅผ ํ†ตํ•ด ๋ฌธ์˜ ์†์žก์ด ์œ„์น˜๋ฅผ ๊ณ„์‚ฐํ•˜๊ณ  ์—ญ๊ธฐ๊ตฌํ•™์„ ํ™œ์šฉํ•˜์—ฌ ๋งค๋‹ˆํ“ฐ๋ ˆ์ดํ„ฐ์˜ ๊ด€์ ˆ ์œ„์น˜๋ฅผ ๊ณ„์‚ฐํ•ฉ๋‹ˆ๋‹ค. ์ œ์•ˆ๋œ ํ”„๋ ˆ์ž„์›Œํฌ์˜ ํšจ์œจ์„ฑ์€ ๋น„ํ™€๋กœ๋…ธ๋ฏน ๋ชจ๋ฐ”์ผ ๋งค๋‹ˆํ“ฐ๋ ˆ์ดํ„ฐ๋ฅผ ์‚ฌ์šฉํ•œ ์‹œ๋ฎฌ๋ ˆ์ด์…˜ ๋ฐ ์‹ค์ œ ์‹คํ—˜์„ ํ†ตํ•ด ๊ฒ€์ฆ๋˜์—ˆ์Šต๋‹ˆ๋‹ค. ๋‘˜ ์งธ, ์ตœ์ ํ™” ๋ฐฉ๋ฒ•์„ ๊ธฐ๋ฐ˜์œผ๋กœํ•œ ์ „์‹  ์ œ์–ด๊ธฐ๋ฅผ ์ œ์•ˆํ•ฉ๋‹ˆ๋‹ค. ์ด ๋ฐฉ๋ฒ•์€ ๋“ฑ์‹ ๋ฐ ๋ถ€๋“ฑ์‹ ์ œํ•œ์กฐ๊ฑด ๋ชจ๋‘์— ๋Œ€ํ•ด ๊ฐ€์ค‘ ํ–‰๋ ฌ์„ ๋ฐ˜์˜ํ•œ ๊ณ„์ธต์  ์ตœ์ ํ™” ๋ฌธ์ œ์˜ ํ•ด๋ฅผ ๊ณ„์‚ฐํ•ฉ๋‹ˆ๋‹ค. ์ด ๋ฐฉ๋ฒ•์€ ๋ชจ๋ฐ”์ผ ๋งค๋‹ˆํ“ฐ๋ ˆ์ดํ„ฐ ๋˜๋Š” ํœด๋จธ๋…ธ์ด๋“œ์™€ ๊ฐ™์ด ์ž์œ ๋„๊ฐ€ ๋งŽ์€ ๋กœ๋ด‡์˜ ์—ฌ์ž์œ ๋„๋ฅผ ํ•ด๊ฒฐํ•˜๊ธฐ ์œ„ํ•ด ๊ฐœ๋ฐœ๋˜์–ด ์ž‘์—… ์šฐ์„  ์ˆœ์œ„์— ๋”ฐ๋ผ ๊ฐ€์ค‘์น˜๊ฐ€ ๋‹ค๋ฅธ ๊ด€์ ˆ ๋™์ž‘์œผ๋กœ ์—ฌ๋Ÿฌ ์ž‘์—…์„ ์ˆ˜ํ–‰ํ•  ์ˆ˜ ์žˆ์Šต๋‹ˆ๋‹ค. ์ œ์•ˆ๋œ ๋ฐฉ๋ฒ•์€ ๊ฐ€์ค‘ ํ–‰๋ ฌ์„ ์ตœ์ ํ™” ๋ฌธ์ œ์˜ 1์ฐจ ์ตœ์  ์กฐ๊ฑด์„ ๋งŒ์กฑํ•˜๋„๋ก ํ•˜๋ฉฐ, Active-set ๋ฐฉ๋ฒ•์„ ํ™œ์šฉํ•˜์—ฌ ๋“ฑ์‹ ๋ฐ ๋ถ€๋“ฑ์‹ ์ž‘์—…์„ ์ฒ˜๋ฆฌํ•ฉ๋‹ˆ๋‹ค. ๋˜ํ•œ, ๋Œ€์นญ์ ์ธ ์˜๊ณต๊ฐ„ ์‚ฌ์˜ ํ–‰๋ ฌ์„ ์‚ฌ์šฉํ•˜์—ฌ ๊ณ„์‚ฐ์ƒ ํšจ์œจ์ ์ž…๋‹ˆ๋‹ค. ๊ฒฐ๊ณผ์ ์œผ๋กœ, ์ œ์•ˆ๋œ ์ œ์–ด๊ธฐ๋ฅผ ํ™œ์šฉํ•˜๋Š” ๋กœ๋ด‡์€ ์šฐ์„  ์ˆœ์œ„์— ๋”ฐ๋ผ ๊ฐœ๋ณ„์ ์ธ ๊ด€์ ˆ ๊ฐ€์ค‘์น˜๋ฅผ ๋ฐ˜์˜ํ•˜์—ฌ ์ „์‹  ์›€์ง์ž„์„ ํšจ๊ณผ์ ์œผ๋กœ ๋ณด์—ฌ์ค๋‹ˆ๋‹ค. ์ œ์•ˆ๋œ ์ œ์–ด๊ธฐ์˜ ํšจ์šฉ์„ฑ์€ ๋ชจ๋ฐ”์ผ ๋งค๋‹ˆํ“ฐ๋ ˆ์ดํ„ฐ์™€ ํœด๋จธ๋…ธ์ด๋“œ๋ฅผ ์ด์šฉํ•œ ์‹คํ—˜์„ ํ†ตํ•ด ๊ฒ€์ฆํ•˜์˜€์Šต๋‹ˆ๋‹ค. ๋งˆ์ง€๋ง‰์œผ๋กœ, ๋ชจ๋ฐ”์ผ ๋งค๋‹ˆํ“ฐ๋ ˆ์ดํ„ฐ์˜ ๋™์  ์ œํ•œ์กฐ๊ฑด๋“ค ์ค‘ ํ•˜๋‚˜๋กœ์„œ ์ž๊ฐ€ ์ถฉ๋Œ ํšŒํ”ผ ์•Œ๊ณ ๋ฆฌ์ฆ˜์„ ์ œ์•ˆํ•ฉ๋‹ˆ๋‹ค. ์ œ์•ˆ๋œ ๋ฐฉ๋ฒ•์€ ๋งค๋‹ˆํ“ฐ๋ ˆ์ดํ„ฐ์™€ ๋ชจ๋ฐ”์ผ ๋กœ๋ด‡ ๊ฐ„์˜ ์ž๊ฐ€ ์ถฉ๋Œ์— ์ค‘์ ์„ ๋‘ก๋‹ˆ๋‹ค. ๋ชจ๋ฐ”์ผ ๋กœ๋ด‡์˜ ๋ฒ„ํผ ์˜์—ญ์„ ๋‘˜๋Ÿฌ์‹ธ๋Š” 3์ฐจ์› ๊ณก๋ฉด์ธ distance buffer border์˜ ๊ฐœ๋…์„ ์ •์˜ํ•ฉ๋‹ˆ๋‹ค. ๋ฒ„ํผ ์˜์—ญ์˜ ๋‘๊ป˜๋Š” ๋ฒ„ํผ ๊ฑฐ๋ฆฌ์ž…๋‹ˆ๋‹ค. ๋งค๋‹ˆํ“ฐ๋ ˆ์ดํ„ฐ์™€ ๋ชจ๋ฐ”์ผ ๋กœ๋ด‡ ์‚ฌ์ด์˜ ๊ฑฐ๋ฆฌ๊ฐ€ ๋ฒ„ํผ ๊ฑฐ๋ฆฌ๋ณด๋‹ค ์ž‘์€ ๊ฒฝ์šฐ, ์ฆ‰ ๋งค๋‹ˆํ“ฐ๋ ˆ์ดํ„ฐ๊ฐ€ ๋ชจ๋ฐ”์ผ ๋กœ๋ด‡์˜ ๋ฒ„ํผ ์˜์—ญ ๋‚ด๋ถ€์— ์žˆ๋Š” ๊ฒฝ์šฐ ์ œ์•ˆ๋œ ์ „๋žต์€ ๋งค๋‹ˆํ“ฐ๋ ˆ์ดํ„ฐ๋ฅผ ๋ฒ„ํผ ์˜์—ญ ๋ฐ–์œผ๋กœ ๋‚ด๋ณด๋‚ด๊ธฐ ์œ„ํ•ด ๋ชจ๋ฐ”์ผ ๋กœ๋ด‡์˜ ์›€์ง์ž„์„ ์ƒ์„ฑํ•ฉ๋‹ˆ๋‹ค. ๋”ฐ๋ผ์„œ ๋งค๋‹ˆํ“ฐ๋ ˆ์ดํ„ฐ๋Š” ๋ฏธ๋ฆฌ ์ •์˜๋œ ๋งค๋‹ˆํ“ฐ๋ ˆ์ดํ„ฐ์˜ ์›€์ง์ž„์„ ์ˆ˜์ •ํ•˜์ง€ ์•Š๊ณ ๋„ ๋ชจ๋ฐ”์ผ ๋กœ๋ด‡๊ณผ์˜ ์ž๊ฐ€ ์ถฉ๋Œ์„ ํ”ผํ•  ์ˆ˜ ์žˆ์Šต๋‹ˆ๋‹ค. ๋ชจ๋ฐ”์ผ ๋กœ๋ด‡์˜ ์›€์ง์ž„์€ ๊ฐ€์ƒ์˜ ํž˜์„ ๊ฐ€ํ•จ์œผ๋กœ์จ ์ƒ์„ฑ๋ฉ๋‹ˆ๋‹ค. ํŠนํžˆ, ํž˜์˜ ๋ฐฉํ–ฅ์€ ์ฐจ๋™ ๊ตฌ๋™ ์ด๋™ ๋กœ๋ด‡์˜ ๋น„ํ™€๋กœ๋…ธ๋ฏน ์ œ์•ฝ ๋ฐ ์กฐ์ž‘๊ธฐ์˜ ๋„๋‹ฌ ๊ฐ€๋Šฅ์„ฑ์„ ๊ณ ๋ คํ•˜์—ฌ ๊ฒฐ์ •๋ฉ๋‹ˆ๋‹ค. ์ œ์•ˆ๋œ ์•Œ๊ณ ๋ฆฌ์ฆ˜์€ 7์ž์œ ๋„ ๋กœ๋ด‡ํŒ”์„ ๊ฐ€์ง„ ์ฐจ๋™ ๊ตฌ๋™ ๋ชจ๋ฐ”์ผ ๋กœ๋ด‡์— ์ ์šฉํ•˜์—ฌ ๋‹ค์–‘ํ•œ ์‹คํ—˜ ์‹œ๋‚˜๋ฆฌ์˜ค์—์„œ ์ž…์ฆ๋˜์—ˆ์Šต๋‹ˆ๋‹ค.A mobile manipulator is a manipulator mounted on a mobile robot. Compared to a fixed-base manipulator, the mobile manipulator can perform various and complex tasks because the mobility is offered by the mobile robot. However, combining two different systems causes several features to be considered when generating the whole-body motion of the mobile manipulator. The features include redundancy, inertia difference, and non-holonomic constraint. The purpose of this thesis is to propose the whole-body motion generation strategy of the mobile manipulator for considering kinematic and dynamic constraints. First, a planning framework is proposed that computes a path for the whole-body configuration of the mobile manipulator to navigate from the initial position, traverse through the door, and arrive at the target position. The framework handles the kinematic constraint imposed by the closed-chain between the robot and door. The proposed framework obtains the path of the whole-body configuration in two steps. First, the path for the pose of the mobile robot and the path for the door angle are computed by using the graph search algorithm. In graph search, an integer variable called area indicator is introduced as an element of state, which indicates where the robot is located relative to the door. Especially, the area indicator expresses a process of door traversal. In the second step, the configuration of the manipulator is computed by the inverse kinematics (IK) solver from the path of the mobile robot and door angle. The proposed framework has a distinct advantage over the existing methods that manually determine several parameters such as which direction to approach the door and the angle of the door required for passage. The effectiveness of the proposed framework was validated through experiments with a nonholonomic mobile manipulator. Second, a whole-body controller is presented based on the optimization method that can consider both equality and inequality constraints. The method computes the optimal solution of the weighted hierarchical optimization problem. The method is developed to resolve the redundancy of robots with a large number of Degrees of Freedom (DOFs), such as a mobile manipulator or a humanoid, so that they can execute multiple tasks with differently weighted joint motion for each task priority. The proposed method incorporates the weighting matrix into the first-order optimality condition of the optimization problem and leverages an active-set method to handle equality and inequality constraints. In addition, it is computationally efficient because the solution is calculated in a weighted joint space with symmetric null-space projection matrices for propagating recursively to a low priority task. Consequently, robots that utilize the proposed controller effectively show whole-body motions handling prioritized tasks with differently weighted joint spaces. The effectiveness of the proposed controller was validated through experiments with a nonholonomic mobile manipulator as well as a humanoid. Lastly, as one of dynamic constraints for the mobile manipulator, a reactive self-collision avoidance algorithm is developed. The proposed method mainly focuses on self-collision between a manipulator and the mobile robot. We introduce the concept of a distance buffer border (DBB), which is a 3D curved surface enclosing a buffer region of the mobile robot. The region has the thickness equal to buffer distance. When the distance between the manipulator and mobile robot is less than the buffer distance, i.e. the manipulator lies inside the buffer region of the mobile robot, the proposed strategy is to move the mobile robot away from the manipulator in order for the manipulator to be placed outside the border of the region, the DBB. The strategy is achieved by exerting force on the mobile robot. Therefore, the manipulator can avoid self-collision with the mobile robot without modifying the predefined motion of the manipulator in a world Cartesian coordinate frame. In particular, the direction of the force is determined by considering the non-holonomic constraint of the differentially driven mobile robot. Additionally, the reachability of the manipulator is considered to arrive at a configuration in which the manipulator can be more maneuverable. To realize the desired force and resulting torque, an avoidance task is constructed by converting them into the accelerations of the mobile robot and smoothly inserted with a top priority into the controller. The proposed algorithm was implemented on a differentially driven mobile robot with a 7-DOFs robotic arm and its performance was demonstrated in various experimental scenarios.1 INTRODUCTION 1 1.1 Motivation 1 1.2 Contributions of thesis 2 1.3 Overview of thesis 3 2 WHOLE-BODY MOTION PLANNER : APPLICATION TO NAVIGATION INCLUDING DOOR TRAVERSAL 5 2.1 Background & related works 7 2.2 Proposed framework 9 2.2.1 Computing path for mobile robot and door angle - S1 10 2.2.1.1 State 10 2.2.1.2 Action 13 2.2.1.3 Cost 15 2.2.1.4 Search 18 2.2.2 Computing path for arm configuration - S2 20 2.3 Results 21 2.3.1 Application to pull and push-type door 21 2.3.2 Experiment in cluttered environment 22 2.3.3 Experiment with different robot platform 23 2.3.4 Comparison with separate planning by existing works 24 2.3.5 Experiment with real robot 29 2.4 Conclusion 29 3 WHOLE-BODY CONTROLLER : WEIGHTED HIERARCHICAL QUADRATIC PROGRAMMING 31 3.1 Related works 32 3.2 Problem statement 34 3.2.1 Pseudo-inverse with weighted least-squares norm for each task 35 3.2.2 Problem statement 37 3.3 WHQP with equality constraints 37 3.4 WHQP with inequality constraints 45 3.5 Experimental results 48 3.5.1 Simulation experiment with nonholonomic mobile manipulator 48 3.5.1.1 Scenario description 48 3.5.1.2 Task and weighting matrix description 49 3.5.1.3 Results 51 3.5.2 Real experiment with nonholonomic mobile manipulator 53 3.5.2.1 Scenario description 53 3.5.2.2 Task and weighting matrix description 53 3.5.2.3 Results 54 3.5.3 Real experiment with humanoid 55 3.5.3.1 Scenario description 55 3.5.3.2 Task and weighting matrix description 55 3.5.3.3 Results 57 3.6 Discussions and implementation details 57 3.6.1 Computation cost 57 3.6.2 Composite weighting matrix in same hierarchy 59 3.6.3 Nullity of WHQP 59 3.7 Conclusion 59 4 WHOLE-BODY CONSTRAINT : SELF-COLLISION AVOIDANCE 61 4.1 Background & related Works 64 4.2 Distance buffer border and its score computation 65 4.2.1 Identification of potentially colliding link pairs 66 4.2.2 Distance buffer border 67 4.2.3 Evaluation of distance buffer border 69 4.2.3.1 Singularity of the differentially driven mobile robot 69 4.2.3.2 Reachability of the manipulator 72 4.2.3.3 Score of the DBB 74 4.3 Self-collision avoidance algorithm 75 4.3.1 Generation of the acceleration for the mobile robot 76 4.3.2 Generation of the repulsive acceleration for the other link pair 82 4.3.3 Construction of an acceleration-based task for self-collision avoidance 83 4.3.4 Insertion of the task in HQP-based controller 83 4.4 Experimental results 86 4.4.1 System overview 87 4.4.2 Experimental results 87 4.4.2.1 Self-collision avoidance while tracking the predefined trajectory 87 4.4.2.2 Self-collision avoidance while manually guiding the end-effector 89 4.4.2.3 Extension to obstacle avoidance when opening the refrigerator 91 4.4.3 Discussion 94 4.5 Conclusion 95 5 CONCLUSIONS 97 Abstract (In Korean) 113 Acknowlegement 116๋ฐ•

    Offline and Online Planning and Control Strategies for the Multi-Contact and Biped Locomotion of Humanoid Robots

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    In the past decades, the Research on humanoid robots made progress forward accomplishing exceptionally dynamic and agile motions. Starting from the DARPA Robotic Challenge in 2015, humanoid platforms have been successfully employed to perform more and more challenging tasks with the eventual aim of assisting or replacing humans in hazardous and stressful working situations. However, the deployment of these complex machines in realistic domestic and working environments still represents a high-level challenge for robotics. Such environments are characterized by unstructured and cluttered settings with continuously varying conditions due to the dynamic presence of humans and other mobile entities, which cannot only compromise the operation of the robotic system but can also pose severe risks both to the people and the robot itself due to unexpected interactions and impacts. The ability to react to these unexpected interactions is therefore a paramount requirement for enabling the robot to adapt its behavior to the task needs and the characteristics of the environment. Further, the capability to move in a complex and varying environment is an essential skill for a humanoid robot for the execution of any task. Indeed, human instructions may often require the robot to move and reach a desired location, e.g., for bringing an object or for inspecting a specific place of an infrastructure. In this context, a flexible and autonomous walking behavior is an essential skill, study of which represents one of the main topics of this Thesis, considering disturbances and unfeasibilities coming both from the environment and dynamic obstacles that populate realistic scenarios.  Locomotion planning strategies are still an open theme in the humanoids and legged robots research and can be classified in sample-based and optimization-based planning algorithms. The first, explore the configuration space, finding a feasible path between the start and goal robotโ€™s configuration with different logic depending on the algorithm. They suffer of a high computational cost that often makes difficult, if not impossible, their online implementations but, compared to their counterparts, they do not need any environment or robot simplification to find a solution and they are probabilistic complete, meaning that a feasible solution can be certainly found if at least one exists. The goal of this thesis is to merge the two algorithms in a coupled offline-online planning framework to generate an offline global trajectory with a sample-based approach to cope with any kind of cluttered and complex environment, and online locally refine it during the execution, using a faster optimization-based algorithm that more suits an online implementation. The offline planner performances are improved by planning in the robot contact space instead of the whole-body robot configuration space, requiring an algorithm that maps the two state spaces.   The framework proposes a methodology to generate whole-body trajectories for the motion of humanoid and legged robots in realistic and dynamically changing environments.  This thesis focuses on the design and test of each component of this planning framework, whose validation is carried out on the real robotic platforms CENTAURO and COMAN+ in various loco-manipulation tasks scenarios. &nbsp

    Towards Semi-Autonomous Control of Heavy-Duty Tracked Earth-Moving Mobile Manipulators : Use Case: The Bulldozer

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    A mobile manipulator (MM) comprises a manipulator attached to a mobile base, making it capable of manipulation tasks in large workspaces. In the field of construction, heavy-duty MMs are extensively used for soil excavation at construction sites. One such machine is the bulldozer, which is widely used because of its robustness and maneuverability. With its onboard blade, the bulldozer shapes terrain and transports soil material by pushing it. However, operating the blade with joysticks to accurately shape the terrain surface and moving material productively are difficult tasks that require extensive training and experience. Automating the motion of the blade, therefore, has the potential to reduce skill requirements, improve productivity, and reduce operatorsโ€™ workloads. This thesis studies and develops methods for the semi-autonomous control of a bulldozer to increase surface quality and earthmoving productivity. These goals were reflected in the main research problems (RPs). Furthermore, as bulldozers drive over the terrain shape generated by the blade, the RPs are coupled because earthmoving productivity is partially dependent on surface quality. The RPs and their coupling were addressed in four publications by coordinating the mobile base and manipulator control and by using the surrounding terrain shape in automatic blade motion reference computations. Challenges to automatic control emerge from the tracked mobile platform driving on rough terrain while the manipulator tool interacts with the soil. It is shown in the first two publications that coordinating the control of the MM mobile base and blade manipulator subsystems can improve surface quality and productivity by temporarily slowing down the machine when the required manipulator joint rates increase or when the tractive performance reduces. The third publication showed that feedforwardโ€“feedback control of the blade manipulator can be used on a real-world bulldozer for accurate terrain shaping. The thesis work culminates in the final publication with an experimental implementation of a semi-autonomous blade control system that continuously maps the worksite terrain and uses it to compute the required blade motion

    Development and Biomechanical Analysis toward a Mechanically Passive Wearable Shoulder Exoskeleton

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    Shoulder disability is a prevalent health issue associated with various orthopedic and neurological conditions, like rotator cuff tear and peripheral nerve injury. Many individuals with shoulder disability experience mild to moderate impairment and struggle with elevating the shoulder or holding the arm against gravity. To address this clinical need, I have focused my research on developing wearable passive exoskeletons that provide continuous at-home movement assistance. Through a combination of experiments and computational tools, I aim to optimize the design of these exoskeletons. In pursuit of this goal, I have designed, fabricated, and preliminarily evaluated a wearable, passive, cam-driven shoulder exoskeleton prototype. Notably, the exoskeleton features a modular spring-cam-wheel module, allowing customizable assistive force to compensate for different proportions of the shoulder elevation moment due to gravity. The results of my research demonstrated that this exoskeleton, providing modest one-fourth gravity moment compensation at the shoulder, can effectively reduce muscle activity, including deltoid and rotator cuff muscles. One crucial aspect of passive shoulder exoskeleton design is determining the optimal anti-gravity assistance level. I have addressed this challenge using computational tools and found that an assistance level within the range of 20-30% of the maximum gravity torque at the shoulder joint yields superior performance for specific shoulder functional tasks. When facing a new task dynamic, such as wearing a passive shoulder exoskeleton, the human neuro-musculoskeletal system adapts and modulates limb impedance at the end-limb (i.e., hand) to enhance task stability. I have presented development and validation of a realistic neuromusculoskeletal model of the upper limb that can predict stiffness modulation and motor adaptation in response to newly introduced environments and force fields. Future studies will explore the model\u27s applicability in predicting stiffness modulation for 3D movements in novel environments, such as passive assistive devices\u27 force fields

    A continuum robotic platform for endoscopic non-contact laser surgery: design, control, and preclinical evaluation

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    The application of laser technologies in surgical interventions has been accepted in the clinical domain due to their atraumatic properties. In addition to manual application of fibre-guided lasers with tissue contact, non-contact transoral laser microsurgery (TLM) of laryngeal tumours has been prevailed in ENT surgery. However, TLM requires many years of surgical training for tumour resection in order to preserve the function of adjacent organs and thus preserve the patientโ€™s quality of life. The positioning of the microscopic laser applicator outside the patient can also impede a direct line-of-sight to the target area due to anatomical variability and limit the working space. Further clinical challenges include positioning the laser focus on the tissue surface, imaging, planning and performing laser ablation, and motion of the target area during surgery. This dissertation aims to address the limitations of TLM through robotic approaches and intraoperative assistance. Although a trend towards minimally invasive surgery is apparent, no highly integrated platform for endoscopic delivery of focused laser radiation is available to date. Likewise, there are no known devices that incorporate scene information from endoscopic imaging into ablation planning and execution. For focusing of the laser beam close to the target tissue, this work first presents miniaturised focusing optics that can be integrated into endoscopic systems. Experimental trials characterise the optical properties and the ablation performance. A robotic platform is realised for manipulation of the focusing optics. This is based on a variable-length continuum manipulator. The latter enables movements of the endoscopic end effector in five degrees of freedom with a mechatronic actuation unit. The kinematic modelling and control of the robot are integrated into a modular framework that is evaluated experimentally. The manipulation of focused laser radiation also requires precise adjustment of the focal position on the tissue. For this purpose, visual, haptic and visual-haptic assistance functions are presented. These support the operator during teleoperation to set an optimal working distance. Advantages of visual-haptic assistance are demonstrated in a user study. The system performance and usability of the overall robotic system are assessed in an additional user study. Analogous to a clinical scenario, the subjects follow predefined target patterns with a laser spot. The mean positioning accuracy of the spot is 0.5 mm. Finally, methods of image-guided robot control are introduced to automate laser ablation. Experiments confirm a positive effect of proposed automation concepts on non-contact laser surgery.Die Anwendung von Lasertechnologien in chirurgischen Interventionen hat sich aufgrund der atraumatischen Eigenschaften in der Klinik etabliert. Neben manueller Applikation von fasergefรผhrten Lasern mit Gewebekontakt hat sich die kontaktfreie transorale Lasermikrochirurgie (TLM) von Tumoren des Larynx in der HNO-Chirurgie durchgesetzt. Die TLM erfordert zur Tumorresektion jedoch ein langjรคhriges chirurgisches Training, um die Funktion der angrenzenden Organe zu sichern und damit die Lebensqualitรคt der Patienten zu erhalten. Die Positionierung des mikroskopis chen Laserapplikators auรŸerhalb des Patienten kann zudem die direkte Sicht auf das Zielgebiet durch anatomische Variabilitรคt erschweren und den Arbeitsraum einschrรคnken. Weitere klinische Herausforderungen betreffen die Positionierung des Laserfokus auf der Gewebeoberflรคche, die Bildgebung, die Planung und Ausfรผhrung der Laserablation sowie intraoperative Bewegungen des Zielgebietes. Die vorliegende Dissertation zielt darauf ab, die Limitierungen der TLM durch robotische Ansรคtze und intraoperative Assistenz zu adressieren. Obwohl ein Trend zur minimal invasiven Chirurgie besteht, sind bislang keine hochintegrierten Plattformen fรผr die endoskopische Applikation fokussierter Laserstrahlung verfรผgbar. Ebenfalls sind keine Systeme bekannt, die Szeneninformationen aus der endoskopischen Bildgebung in die Ablationsplanung und -ausfรผhrung einbeziehen. Fรผr eine situsnahe Fokussierung des Laserstrahls wird in dieser Arbeit zunรคchst eine miniaturisierte Fokussieroptik zur Integration in endoskopische Systeme vorgestellt. Experimentelle Versuche charakterisieren die optischen Eigenschaften und das Ablationsverhalten. Zur Manipulation der Fokussieroptik wird eine robotische Plattform realisiert. Diese basiert auf einem lรคngenverรคnderlichen Kontinuumsmanipulator. Letzterer ermรถglicht in Kombination mit einer mechatronischen Aktuierungseinheit Bewegungen des Endoskopkopfes in fรผnf Freiheitsgraden. Die kinematische Modellierung und Regelung des Systems werden in ein modulares Framework eingebunden und evaluiert. Die Manipulation fokussierter Laserstrahlung erfordert zudem eine prรคzise Anpassung der Fokuslage auf das Gewebe. Dafรผr werden visuelle, haptische und visuell haptische Assistenzfunktionen eingefรผhrt. Diese unterstรผtzen den Anwender bei Teleoperation zur Einstellung eines optimalen Arbeitsabstandes. In einer Anwenderstudie werden Vorteile der visuell-haptischen Assistenz nachgewiesen. Die Systemperformanz und Gebrauchstauglichkeit des robotischen Gesamtsystems werden in einer weiteren Anwenderstudie untersucht. Analog zu einem klinischen Einsatz verfolgen die Probanden mit einem Laserspot vorgegebene Sollpfade. Die mittlere Positioniergenauigkeit des Spots betrรคgt dabei 0,5 mm. Zur Automatisierung der Ablation werden abschlieรŸend Methoden der bildgestรผtzten Regelung vorgestellt. Experimente bestรคtigen einen positiven Effekt der Automationskonzepte fรผr die kontaktfreie Laserchirurgie
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