index.json

[{"authors":null,"categories":null,"content":"  Dongdong studied at Zhejiang University in China where he received a Master of Mechatronics degree in 2016. His research focused on high precision control of hydraulic system at the State Key Laboratory of Fluid Power and Mechatronic Systems under the supervision of Prof. Qingfeng Wang. In January 2018, he began his PhD study at the Mechatronics, Controls and Robotics Laboratory in New York University under the supervision of Prof. Vikram Kapila. He led a 10-people research group--The Legged Group @ NYU. His current research focuses on planning and control, with a special emphasis on legged locomotion for autonomous robot. He is also more broadly interested in questions at the intersection of optimization, machine learning and their application to legged robots.     #slide-window { position: relative; width: 500px; height: 300px; overflow: hidden; top: 0px; left: 0px; } #slides-list { width: 500px; height: 300px; position: absolute; margin: 0px; padding: 0px; -webkit-transform: translate3d(0px, 0px, 0px); transform: translate3d(0px, 0px, 0px); transition: all 0.66s ease; -webkit-transition: all 0.66s ease; } .slide { list-style: none; position: relative; float: left; margin: 0; padding: 0; width: 500px; height: 300px; background: #ccc; text-align: center; line-height: 100%; background-size: cover; background-position: 50% 50%; color: #fff; -webkit-transform: translate3d(0px, 0px, 0px); -webkit-transform-style: preserve-3d; } .nav { position: relative; z-index: 9; top: 45%; cursor: pointer; color: #fff; opacity: 0.7; transition: all 0.66s ease; -webkit-transition: all 0.66s ease; } .nav:hover { opacity: 1.0; } #left { left: 3%; float: left; } #right { right: 3%; float: right; }            sliderJQuery = jQuery.noConflict(); sliderJQuery(function( $ ) { $.global = new Object(); $.global.total = 0; $(document).ready(function () { var slideWindowWidth = $('#slide-window').width(); var slideCount = $('#slides-list li').length; var totalSlidesWidth = slideCount * slideWindowWidth; $.global.item = 0; $.global.total = slideCount; $('.slide').css('width', slideWindowWidth + 'px'); $('#slides-list').css('width', totalSlidesWidth + 'px'); $('#left').click(function () { resetAutoSlide(); performSlide('back'); }); $('#right').click(function () { resetAutoSlide(); performSlide('forward'); }); }); function performSlide(direction) { if (direction == 'back') { var nextSlideId = $.global.item - 1; } if (direction == 'forward') { var nextSlideId = $.global.item + 1; } if (nextSlideId == -1) { moveCss($.global.total - 1); } else if (nextSlideId == $.global.total) { moveCss(0); } else { moveCss(nextSlideId); } } function moveCss(nextSlideId) { var slideWindowWidth = $('#slide-window').width(); var margin = slideWindowWidth * nextSlideId; $('#slides-list').css('transform', 'translate3d(-' + margin + 'px,0px,0px)'); $.global.item = nextSlideId; } var autoSlide = parseInt(\"10000\", 10); var autoSlideInterval; function resetAutoSlide(){ if(autoSlide) { if(autoSlideInterval) { clearInterval(autoSlideInterval); } autoSlideInterval = setInterval(function(){ performSlide('forward'); }, autoSlide) } } resetAutoSlide(); });  ","date":-62135596800,"expirydate":-62135596800,"kind":"term","lang":"en","lastmod":-62135596800,"objectID":"2525497d367e79493fd32b198b28f040","permalink":"https://ddliu365.github.io/author/dongdong-liu/","publishdate":"0001-01-01T00:00:00Z","relpermalink":"/author/dongdong-liu/","section":"authors","summary":"Dongdong studied at Zhejiang University in China where he received a Master of Mechatronics degree in 2016. His research focused on high precision control of hydraulic system at the State Key Laboratory of Fluid Power and Mechatronic Systems under the supervision of Prof.","tags":null,"title":"Dongdong Liu","type":"authors"},{"authors":null,"categories":null,"content":" Dongdong Liu, Yuhang Lin, Alexander Koldy, Vikram Kapila\n |Abstract|Code|Paper|Concept|Results|Experiment|Acknowledgment|\nAbstract In recent years, there has been a growing interest in the use of optimal control techniques for diverse application scenarios being envisioned for humanoid robots. Throwing is a common human activity used in a variety of situations, including sports, hunting, rescue, etc. Optimization approaches have previously been considered to maximize the simulated throw performance for humans. Experimental approaches for improving human throw performance have been restricted to observation and mimicry of high performing athletes. In the case of robotics, prior research on throw performance improvement using optimization has been limited to simulations studies, with scant research considering experimental validation. To address this research gap, in this effort, we consider the optimal design, experimental implementation, and analysis of a whole-body throwing motion in a double support humanoid robot with the use of a differential dynamic programming (DDP) approach. We provide results from repeated experiments to demonstrate that the proposed DDP method significantly improves the throwing performance for a 23 degrees-of-freedom humanoid robot in contrast to a previously proposed key-frame (KF) method. With the framework of this paper, a humanoid robot can perform highly dynamic whole-body throwing tasks, achieving optimal throwing distance while maintaining balance stability.\nPaper Concept The concept of a humanoid throwing motion: (a) initial pose, (b) preparation pose, (c) throw pose, and (d) recovery pose. A ball is released from the robot\u0026rsquo;s right gripper at the end of the throw phase.\n Results Simulated joint positions for differential-dynamic programming (DDP) approach. Lower extremity:\n Upper extremity:\n Framework:\n Throw distance comparision for both differential-dynamic programming (DDP) and keyframe (KF) approach\n Experiment (a) A humanoid with encoder-equipped motors mounted on each joint and an inertial measurement unit (IMU) mounted on its pelvis, and (b) the throwing testbed\n Timeline snapshots: Throwing experiment with the DDP approach\n Timeline snapshots: Throwing experiment with the KF approach\n Acknowledgment Work supported in part by the National Science Foundation under an ITEST grant DRL-1614085, RET Site grant EEC-1542286, and DRK12 grant DRL-1417769. D. Liu thanks his lab colleagues, particularly P. Chauhan, for helping edit early drafts of the manuscript.\n","date":1635638400,"expirydate":-62135596800,"kind":"page","lang":"en","lastmod":1635638400,"objectID":"f43cb603bbf9603dbdbf47041318f258","permalink":"https://ddliu365.github.io/project/double_throw/","publishdate":"2021-10-31T00:00:00Z","relpermalink":"/project/double_throw/","section":"project","summary":"Whole-Body Optimization of Long-Distance Throw for a Humanoid in Double Support","tags":["control","robotics"],"title":"Humanoid Double-Support Throw","type":"project"},{"authors":["Dongdong Liu","Yuhang Lin","Vikram Kapila"],"categories":null,"content":"","date":1628380800,"expirydate":-62135596800,"kind":"page","lang":"en","lastmod":1628380800,"objectID":"a3cff9ba6dcd5458b60669a9afe3b90f","permalink":"https://ddliu365.github.io/publication/rollover/","publishdate":"2021-08-08T00:00:00Z","relpermalink":"/publication/rollover/","section":"publication","summary":"Prior research on humans undergoing a forward fall has revealed that the deployment of a rollover strategy along the longitudinal axis can lower the impact force experienced on the hand to effectively reduce wrist injuries. Yet, analogous research for humanoids has received scant attention. To address this research gap, in this work, we consider the optimal design, implementation, and examination of a rollover strategy--similar to the one for humans--for  a humanoid robot by employing a differential dynamic programming (DDP) approach.","tags":null,"title":"A Rollover Strategy for Wrist Damage Reduction in a Forward Falling Humanoid","type":"publication"},{"authors":null,"categories":null,"content":"","date":1628380800,"expirydate":-62135596800,"kind":"page","lang":"en","lastmod":1628380800,"objectID":"35f64ff52aacd0d08cf09df8c01138c5","permalink":"https://ddliu365.github.io/project/rollover/","publishdate":"2021-08-08T00:00:00Z","relpermalink":"/project/rollover/","section":"project","summary":"A Rollover Strategy for Wrist Damage Reduction in a Forward Falling Humanoid","tags":["control","robotics"],"title":"Humanoid Rollover","type":"project"},{"authors":["Dongdong Liu","Hoon Jeong","Aoxue Wei","Vikram Kapila"],"categories":null,"content":"","date":1604448000,"expirydate":-62135596800,"kind":"page","lang":"en","lastmod":1604448000,"objectID":"603daa6bc234da027d47973baf5587c2","permalink":"https://ddliu365.github.io/publication/forecast/","publishdate":"2020-11-04T00:00:00Z","relpermalink":"/publication/forecast/","section":"publication","summary":"To improve on prior works, we consider a bidirectional long short-term memory (BLSTM) network, which makes use of historical measurements of system states as inputs, to effectively predict fall probability in real time. Through extensive simulation experiments, which utilize external forces with random magnitudes, directions, locations, and times of application, we demonstrate that the proposed BLSTM network can robustly predict fall events.","tags":[],"title":"Bidirectional LSTM-based Network for Fall Prediction in a Humanoid","type":"publication"},{"authors":["Dongdong Liu","Yang Liu","Yifan Xing","Shramana Ghosh","Vikram Kapila"],"categories":null,"content":"","date":1604448000,"expirydate":-62135596800,"kind":"page","lang":"en","lastmod":1604448000,"objectID":"14a2470479c392148bd0ef6ac028b208","permalink":"https://ddliu365.github.io/publication/landing/","publishdate":"2020-11-04T00:00:00Z","relpermalink":"/publication/landing/","section":"publication","summary":"Previously, researchers have designed a parachute landing fall (PLF) motion heuristically by considering only one side of a humanoid. However, such a model cannot be reliably applied to a full humanoid without considering actual contact environment in trajectory optimization. We consider parachute landing based on a full biped robot with a rigid contact model, utilizing the differential dynamic programming (DDP) method.","tags":[],"title":"DDP-based Parachute Landing Optimization for a Humanoid","type":"publication"},{"authors":null,"categories":null,"content":"","date":1604448000,"expirydate":-62135596800,"kind":"page","lang":"en","lastmod":1604448000,"objectID":"a61ee29815523abd5b87b7ea9b9af763","permalink":"https://ddliu365.github.io/project/forecast/","publishdate":"2020-11-04T00:00:00Z","relpermalink":"/project/forecast/","section":"project","summary":"Bidirectional LSTM-based Network for Fall Prediction in a Humanoid","tags":["learning","robotics"],"title":"Humanoid Forecast","type":"project"},{"authors":null,"categories":null,"content":"","date":1604448000,"expirydate":-62135596800,"kind":"page","lang":"en","lastmod":1604448000,"objectID":"1d35e09edc696f04ff96a3e0554f66f3","permalink":"https://ddliu365.github.io/project/landing/","publishdate":"2020-11-04T00:00:00Z","relpermalink":"/project/landing/","section":"project","summary":"DDP-based Parachute Landing Optimization for a Humanoid","tags":["robotics","control"],"title":"Humanoid Landing","type":"project"},{"authors":null,"categories":null,"content":"","date":1598918400,"expirydate":-62135596800,"kind":"page","lang":"en","lastmod":1598918400,"objectID":"6094ac1b342a45deffad496c95f1ad1c","permalink":"https://ddliu365.github.io/project/snac/","publishdate":"2020-09-01T00:00:00Z","relpermalink":"/project/snac/","section":"project","summary":"Simultaneous Navigation and Construction Benchmarking Environments","tags":["learning"],"title":"Deep mobile printing","type":"project"},{"authors":null,"categories":null,"content":"","date":1546300800,"expirydate":-62135596800,"kind":"page","lang":"en","lastmod":1546300800,"objectID":"b7dbbc8ee5afbe1ecc8b469a93a7c545","permalink":"https://ddliu365.github.io/projectpage/","publishdate":"2019-01-01T00:00:00Z","relpermalink":"/projectpage/","section":"","summary":"Hello!","tags":null,"title":"Landing Page","type":"widget_page"},{"authors":null,"categories":null,"content":"Upcoming\u0026hellip;\n","date":1461715200,"expirydate":-62135596800,"kind":"page","lang":"en","lastmod":1461715200,"objectID":"1f0a7dd52b4a417cfc04d3c34ceecacf","permalink":"https://ddliu365.github.io/project/sphere_joint/","publishdate":"2016-04-27T00:00:00Z","relpermalink":"/project/sphere_joint/","section":"project","summary":"Hard Ware Development and Control of Novel Sphere Joint Mechanism","tags":["robotics"],"title":"Sphere Joint Mechanism","type":"project"},{"authors":null,"categories":null,"content":"","date":1372636800,"expirydate":-62135596800,"kind":"page","lang":"en","lastmod":1372636800,"objectID":"d4df9481c1a045cd9af19db74285e895","permalink":"https://ddliu365.github.io/project/6urs/","publishdate":"2013-07-01T00:00:00Z","relpermalink":"/project/6urs/","section":"project","summary":"Automatically Reconfigurable Parallel Walking Robot Design with Manipulators","tags":["robotics"],"title":"Reconfigurable Parallel Robot","type":"project"},{"authors":null,"categories":null,"content":"","date":1356912000,"expirydate":-62135596800,"kind":"page","lang":"en","lastmod":1356912000,"objectID":"70070ea6b8f966ccb769430d5213455c","permalink":"https://ddliu365.github.io/project/fruit_robot/","publishdate":"2012-12-31T00:00:00Z","relpermalink":"/project/fruit_robot/","section":"project","summary":"Hard Ware Development and Programming of Smart Fruit Picking Robot Car","tags":["control","robotics"],"title":"Fruit Picking Robot","type":"project"},{"authors":null,"categories":null,"content":"  NYU Tandon Robotics Summer Program Instructor, K12 course, New York University, 2019\n  NYU Tandon Robotics Summer Program Instructor, K12 course, New York University, 2018\n  Mentorship  Alexander Koldy Aoxue Wei Hoon Jeong Julian Tang Kunal Sheth Michael Loughnane Samuel Rossberg Yang Liu Yifan Xing Yuhang Lin  ","date":-62135596800,"expirydate":-62135596800,"kind":"page","lang":"en","lastmod":-62135596800,"objectID":"322dbaccf72a6d71f827fdb2866be935","permalink":"https://ddliu365.github.io/teaching/","publishdate":"0001-01-01T00:00:00Z","relpermalink":"/teaching/","section":"","summary":"  NYU Tandon Robotics Summer Program Instructor, K12 course, New York University, 2019\n  NYU Tandon Robotics Summer Program Instructor, K12 course, New York University, 2018\n  Mentorship  Alexander Koldy Aoxue Wei Hoon Jeong Julian Tang Kunal Sheth Michael Loughnane Samuel Rossberg Yang Liu Yifan Xing Yuhang Lin  ","tags":null,"title":"","type":"page"},{"authors":null,"categories":null,"content":"","date":-62135596800,"expirydate":-62135596800,"kind":"page","lang":"en","lastmod":-62135596800,"objectID":"79dd065a6e6fc382d8495f5956705282","permalink":"https://ddliu365.github.io/project/hydraulic_control/","publishdate":"0001-01-01T00:00:00Z","relpermalink":"/project/hydraulic_control/","section":"project","summary":"Structural Design and Experiment with Fuzzy-PID Control for the Hydraulic Pressure Control System","tags":["control"],"title":"Hydraulic Pressure Control","type":"project"}]