[{"data":1,"prerenderedAt":-1},["ShallowReactive",2],{"doc-detail-85628-en":3,"doc-seo-85628-105":29,"detail-sidebar-cat-0-en-105":91},{"code":4,"msg":5,"data":6},0,"success",{"doc_id":7,"user_id":8,"nickname":9,"user_avatar":10,"doc_module":4,"category_id":11,"category_name":12,"doc_title":13,"doc_description":14,"doc_content":15,"file_id":16,"file_url":17,"file_type":18,"file_size":19,"view_count":20,"is_deleted":4,"is_public":20,"is_downloadable":20,"audit_status":20,"page_count":21,"language":22,"language_code":23,"site_id":24,"html_lang":23,"table_of_contents":25,"faqs":26,"seo_title":13,"seo_description":14,"update_tm":27,"read_time":28},85628,4810365810221,"Aurora","https://ap-avatar.wpscdn.com/davatar_155a257f0dc6eb9ab79c44ca47cae57d",8,"Research & Report","Contact-Consistent Interaction Dynamics Normalization for Predictive Physical Human–Robot Interaction","Safe physical human–robot interaction on floating-base robots depends on regulating contact-consistent interaction dynamics under changing contact constraints. The work proposes a contact-consistent normalization where the residual end-effector channel becomes a linear double integrator in acceleration coordinates. Discrete prediction matrices are configuration- and support-mode invariant, with posture and contacts entering only via task-inertia force recovery and constraint terms. The controller combines a constant-Hessian receding-horizon QP, an acceleration-disturbance observer, and a priority-consistent realization, linking to impedance as a limiting case. MuJoCo experiments evaluate sustained forces, shock transmission, and scheduled contact-model changes, highlighting disturbance estimation as key to fixed-stance accuracy.","Contact-Consistent Interaction Dynamics Normalization for Predictive Physical Human–Robot Interaction  \nYongyan Cao  \narXiv :2606 . 14617v2 [ cs .RO] 11 Jul 2026  \nAbstract—Safe physical human–robot interaction on floatingbase robots requires interaction regulation under changing contact constraints. We develop a contact-consistent normalization in which the residual end-effector channel is represented as alinear double integrator in acceleration coordinates. Both discrete prediction matrices are independent of configuration and support mode; posture and contact enter only through task-inertia force recovery and constraints. The controller combines a constantHessian receding-horizon QP, an acceleration-disturbance observer, and a priority-consistent realization. Classical operationalspace impedance is shown to be the unconstrained infinitehorizon limit. MuJoCo experiments on a 17-DOF biped and a Menagerie-derived Unitree G1 model evaluate sustained forces, transmitted shocks, and scheduled contact-model changes. Disturbance estimation is the dominant source of fixed-stance accuracy, while covariance inflation gives only scenario-dependent transient benefit. Dynamic walking and hardware validation remain outside the present evidence.  \nIndex Terms—Interaction dynamics, whole-body control, model predictive control, impedance control, floating-base robots, physical human–robot interaction, contact-consistent dynamics, legged manipulation.  \nI. INTRODUCTION  \nLegged and floating-base robots must increasingly do more than locomote: they must physically interact with people and their surroundings while keeping balance. Safe interaction on such platforms is fundamentally a problem of interaction dynamics—the closed-loop relation between the arm endeffector force and motion—coupled, through the contact constraints, to the whole-body balance task. These objectives are tightly coupled—arm motions shift the center of mass (CoM), changing contact force distribution, while ground reactions propagate back through the body and appear as disturbancesat the end-effector. Classical fixed-base impedance control [1] and its MPC extensions [2], [3] cannot address this coupling because they assume the robot base is rigidly anchored.  \nThe dominant paradigm for whole-body control of legged systems decouples the problem into two layers: a centroidal MPC that optimizes ground reaction forces (GRFs) using a linearized single rigid-body dynamics (SRBD) model [4],[5], and an inner WBC layer that resolves these forces into joint torques via a prioritized QP [6], [7] . This architecture achieves remarkable locomotive agility—the MIT Cheetah  \n3 [4] executes high-speed bounding and stair climbing—but allocates 100% of the robot’s control authority to locomotion  \nY. Cao is with Voryx Robotics, San Jose, CA 95136, USA. E-mail: [yongyancao@gmail.com](yongyancao@gmail.com)  \nand base-posture maintenance. Any external arm interaction is treated as a disturbance to be suppressed, not as a channel to be actively regulated. A biped reaching to assist a human standing beside it, or a quadruped manipulating a valve while maintaining stance, cannot be handled by these frameworks with the compliance and zero-steady-state-error guarantees required for safe pHRI.  \nConversely, impedance MPC methods designed for fixedbase manipulators [2], [3], [8], [9] lack an unactuated base state, generalized-coordinate partitioning, or contact-consistent mass inverses. They assume an infinite-mass ground connection and cannot model the propagation of foot contact forces to end-effector apparent inertia. Deploying them directly on a floating-base platform produces steady-state torque errors and potential instability during contact transitions.  \nThe technical gap is therefore not merely the absence of another whole-body controller. It is the absence of a representation in which interaction dynamics remain structurally the same as robot posture, contact mode, and apparent inertia chang","cbCaistvj0EUeWlc","https://ap.wps.com/l/cbCaistvj0EUeWlc","pdf",811253,1,9,"English","en",105,"# Introduction\n# Related Work\n# Interaction Dynamics on Floating-Base Robots\n# Contact-Consistent Normalization\n# Predictive Regulation of Normalized Dynamics\n# Contact-Mode Changes\n# Impedance-Equivalence Proof\n# Stability Analysis","[{\"question\":\"What problem does contact-consistent interaction dynamics normalization address for floating-base robots?\",\"answer\":\"It addresses the need to regulate end-effector interaction dynamics safely while contact constraints and contact modes change, which fixed-base impedance or MPC methods cannot represent for an unactuated floating base.\"},{\"question\":\"How are the predictive model and matrices affected by robot configuration and support mode?\",\"answer\":\"The discrete prediction matrices become invariant to configuration and support mode after normalization; posture and contacts affect only force recovery and constraint terms through the recovery and constraint components.\"},{\"question\":\"What control components are combined in the proposed controller?\",\"answer\":\"The method integrates a constant-Hessian receding-horizon QP, an acceleration-disturbance observer, and a priority-consistent whole-body realization, with an optional covariance inflation mechanism.\"}]",1784205055,23,{"code":4,"msg":30,"data":31},"ok",{"site_id":24,"language":23,"slug":32,"title":13,"keywords":33,"description":14,"schema_data":34,"social_meta":86,"head_meta":88,"extra_data":90,"updated_unix":27},"contact-consistent-interaction-dynamics-normalization-for-predictive-physical-humanrobot-interaction","",{"@graph":35,"@context":85},[36,53,68],{"@type":37,"itemListElement":38},"BreadcrumbList",[39,43,47,50],{"item":40,"name":41,"@type":42,"position":20},"https://docshare.wps.com","Home","ListItem",{"item":44,"name":45,"@type":42,"position":46},"https://docshare.wps.com/document/","Document",2,{"item":48,"name":12,"@type":42,"position":49},"https://docshare.wps.com/document/research-report/",3,{"item":51,"name":13,"@type":42,"position":52},"https://docshare.wps.com/document/contact-consistent-interaction-dynamics-normalization-for-predictive-physical-humanrobot-interaction/85628/",4,{"url":51,"name":13,"@type":54,"author":55,"headline":13,"publisher":57,"fileFormat":60,"inLanguage":23,"description":14,"dateModified":61,"datePublished":62,"encodingFormat":60,"isAccessibleForFree":63,"interactionStatistic":64},"DigitalDocument",{"name":9,"@type":56},"Person",{"url":40,"name":58,"@type":59},"DocShare","Organization","application/pdf","2026-07-17","2026-07-16",true,{"@type":65,"interactionType":66,"userInteractionCount":20},"InteractionCounter",{"@type":67},"ViewAction",{"@type":69,"mainEntity":70},"FAQPage",[71,77,81],{"name":72,"@type":73,"acceptedAnswer":74},"What problem does contact-consistent interaction dynamics normalization address for floating-base robots?","Question",{"text":75,"@type":76},"It addresses the need to regulate end-effector interaction dynamics safely while contact constraints and contact modes change, which fixed-base impedance or MPC methods cannot represent for an unactuated floating base.","Answer",{"name":78,"@type":73,"acceptedAnswer":79},"How are the predictive model and matrices affected by robot configuration and support mode?",{"text":80,"@type":76},"The discrete prediction matrices become invariant to configuration and support mode after normalization; posture and contacts affect only force recovery and constraint terms through the recovery and constraint components.",{"name":82,"@type":73,"acceptedAnswer":83},"What control components are combined in the proposed controller?",{"text":84,"@type":76},"The method integrates a constant-Hessian receding-horizon QP, an acceleration-disturbance observer, and a priority-consistent whole-body realization, with an optional covariance inflation mechanism.","https://schema.org",{"og:url":51,"og:type":87,"og:title":13,"og:site_name":58,"og:description":14},"article",{"robots":89,"canonical":51},"index,follow",{"doc_id":7,"site_id":24},{"code":4,"msg":5,"data":92},[93,97,101,105,110,115,120,123,127,130,134],{"id":20,"doc_module":4,"doc_module_name":45,"category_name":94,"show_sort_weight":95,"slug":96},"Story & Novel",90,"story-novel",{"id":46,"doc_module":4,"doc_module_name":45,"category_name":98,"show_sort_weight":99,"slug":100},"Literature",80,"literature",{"id":52,"doc_module":4,"doc_module_name":45,"category_name":102,"show_sort_weight":103,"slug":104},"Exam",70,"exam",{"id":106,"doc_module":4,"doc_module_name":45,"category_name":107,"show_sort_weight":108,"slug":109},5,"Comic",60,"comic",{"id":111,"doc_module":4,"doc_module_name":45,"category_name":112,"show_sort_weight":113,"slug":114},6,"Technology",50,"technology",{"id":116,"doc_module":4,"doc_module_name":45,"category_name":117,"show_sort_weight":118,"slug":119},7,"Healthcare",40,"healthcare",{"id":11,"doc_module":4,"doc_module_name":45,"category_name":12,"show_sort_weight":121,"slug":122},30,"research-report",{"id":21,"doc_module":4,"doc_module_name":45,"category_name":124,"show_sort_weight":125,"slug":126},"Religion & Spirituality",20,"religion-spirituality",{"id":125,"doc_module":4,"doc_module_name":45,"category_name":128,"show_sort_weight":125,"slug":129},"World Cup","world-cup",{"id":131,"doc_module":4,"doc_module_name":45,"category_name":132,"show_sort_weight":131,"slug":133},10,"Lifestyle","lifestyle",{"id":135,"doc_module":4,"doc_module_name":45,"category_name":136,"show_sort_weight":106,"slug":137},19,"General","general"]