Bipedal Research Articles

Self-Generated Lower Body Negative Pressure Exercise: A Low Power Countermeasure for Acute Space Missions.

Microgravity in spaceflight produces headward fluid shifts which probably contribute to Spaceflight-Associated Neuro-Ocular Syndrome (SANS). Developing new methods to mitigate these shifts is crucial for preventing SANS. One possible strategy is the use of self-generated lower body negative pressure (LBNP). This study evaluates biological or physiological effects induced by bed rest to simulate adaptations to microgravity. Participants were tested during powered LBNP and dynamic self-generated (SELF) LBNP at 25 mmHg for 15 min. The results were compared to the physiologic responses observed in seated upright and supine positions without LBNP, which served as controls for normal gravitational effects on fluid dynamics. Eleven participants' (five male, six female) heart rates, blood pressures, and cross-sectional areas (CSA) of left and right internal jugular veins (IJV) were monitored. Self-generated LBNP, which requires mild to moderate physical activity, significantly elevated heart rate and blood pressure (p < 0.01). Self-generated LBNP also significantly reduced right IJV CSA compared to supine position (p = 0.005), though changes on the left side were not significant (p = 0.365). While the effects of SELF and traditional LBNP on IJV CSA were largely similar, traditional LBNP significantly reduced IJV CSA on both sides. Given its low mass, volume, and power requirements, SELF LBNP is a promising countermeasure against SANS. Results from this study warrant longer-term studies of SELF LBNP under simulated spaceflight conditions.

Absorption pharmacokinetics and feasibility of intranasal dexmedetomidine in patients under general anaesthesia.

The use of intranasal dexmedetomidine is hampered by a limited understanding of its absorption pharmacokinetics. We examined the pharmacokinetics and feasibility of intranasal dexmedetomidine administered in the supine position to adult patients undergoing general anaesthesia. Twenty-eight patients between 35 and 80 years of age, ASA 1-3 and weight between 50 and 100 kg, who underwent elective unilateral total hip or knee arthroplasty under general anaesthesia were recruited. All patients received 100 μg of intranasal dexmedetomidine after anaesthesia induction. Six venous blood samples (at 0, 5, 15, 45, 60, 240 min timepoints from dexmedetomidine administration) were collected from each patient and dexmedetomidine plasma concentrations were measured. Concentration-time profiles after nasal administration were pooled with earlier data from a population analysis of intravenous dexmedetomidine (n = 202) in order to estimate absorption parameters using nonlinear mixed effects. Peak concentration (CMAX) and time (TMAX) were estimated using simulation (n = 1000) with parameter estimates and their associated variability. There were 28 adult patients with a mean (SD) age of 66 (8) years and weight of 83 (10) kg. The mean weight-adjusted dose of dexmedetomidine was 1.22 (0.15) μg kg-1. CMAX 0.273 μg L-1 was achieved at 98 min after intranasal administration (TMAX). The relative bioavailability of dexmedetomidine was 80% (95% CI 75-91%). The absorption half-time (TABS = 120 min; 95% CI 90-147 min) was slower than that in previous pharmacokinetic studies on adult patients. Perioperative haemodynamics of all patients remained stable. Administration of intranasal dexmedetomidine in the supine position during general anaesthesia is feasible with good bioavailability. This administration method has slower absorption when compared to awake patients in upright position, with consequent concentrations attained after TMAX for several hours.

When and where to step: Terrain-aware real-time footstep location and timing optimization for bipedal robots

Online footstep planning is essential for bipedal walking robots, allowing them to walk in the presence of disturbances and sensory noise. Most of the literature on the topic has focused on optimizing the footstep placement while keeping the step timing constant. In this work, we introduce a footstep planner capable of optimizing footstep placement and step time online. The proposed planner, consisting of an Interior Point Optimizer (IPOPT) and an optimizer based on Augmented Lagrangian (AL) method with analytical gradient descent, solves the full dynamics of the Linear Inverted Pendulum (LIP) model in real time to optimize for footstep location as well as step timing at the rate of 200 Hz. We show that such asynchronous real-time optimization with the AL method (ARTO-AL) provides the required robustness and speed for successful online footstep planning. Furthermore, ARTO-AL can be extended to plan footsteps in 3D, allowing terrain-aware footstep planning on uneven terrains. Compared to an algorithm with no footstep time adaptation, our proposed ARTO-AL demonstrates increased stability in simulated walking experiments as it can resist pushes on flat ground and on a 10° ramp up to 120 N and 100 N respectively. Videos22https://youtu.be/2pwDTEJzmjI. and open-source code33https://github.com/WangKeAlchemist/ARTO-AL/tree/master. are released.

Stable underactuated biped locomotion on various geometrical surfaces

Stable underactuated biped locomotion on various geometrical surfaces

Struktur Gerak Tari Sayak di Desa Air Batu Kecamatan Ranah Pemberap Kabupaten Merangin Provinsi Jambi

The purpose of this study is to explain and describe the movement structure of Sayak Dance in Air Batu Village, Ranah Pemberap District, Merangin Regency, Jambi Province. This type of research is qualitative research with descriptive methods. Research instruments are researchers themselves and assisted by supporting instruments such as stationery and cameras. Data was collected through observation, interviews, and documentation. The steps of analyzing data are data collection, data reduction, data presentation and conclusions. The results showed that the relationship of basic elements, Sayak Dance has basic elements related to the attitude of the movement of body parts, starting from the head, body, hands, feet. The attitudes and movements contained in the Sayak Dance consist of: 1) attitudes and movements seen in a) the attitude of the head is upright, upright motion on the head does not exist. 2) Posture and gestures are seen in: a) upright, upright and leaning forward posture b) Motion on the body is absent 3) Posture and hand gestures are seen in: a) attitude on the hand lift sambah b) motion on the hand open straight sambah, open right sambah, pat me up, pat the right side of the leaf, pat the bottom slap, pat the back 4) attitude and motion on the feet seen in: a) attitude of the right foot, squat, middle stance, right lift, lift left, and bend. The grammatical hierarchical relationship system contained in Sayak Dance consists of 15 motifs, 8 phrases, 4 sentences and 1 cluster. Sayak dance includes syntagmatic relationships, relationships that are like links that cannot be separated or exchanged between the sati and others.

Injury Risk Predictions in Lunar Terrain Vehicle (LTV) Extravehicular Activities (EVAs): A Pilot Study

Extravehicular activities will play a crucial role in lunar exploration on upcoming Artemis missions and may involve astronauts operating a lunar terrain vehicle (LTV) in a standing posture. This study assessed kinematic response and injury risks using an active muscle human body model (HBM) restrained in an upright posture on the LTV by simulating dynamic acceleration pulses related to lunar surface irregularities. Linear accelerations and rotational displacements of 5 lunar obstacles (3 craters; 2 rocks) over 5 slope inclinations were applied across 25 simulations. All body injury metrics were below NASA’s injury tolerance limits, but compressive forces were highest in the lumbar (250–550N lumbar, tolerance: 5300N) and lower extremity (190–700N tibia, tolerance: 1350N) regions. There was a strong association between the magnitudes of body injury metrics and LTV resultant linear acceleration (ρ = 0.70–0.81). There was substantial upper body motion, with maximum forward excursion reaching 375 mm for the head and 260 mm for the chest. Our findings suggest driving a lunar rover in an upright posture for these scenarios is a low severity impact presenting low body injury risks. Injury metrics increased along the load path, from the lower body (highest metrics) to the upper body (lowest metrics). While upper body injury metrics were low, increased body motion could potentially pose a risk of injury from flail and occupant interaction with the surrounding vehicle, suit, and restraint hardware.

Identification and impact of failure of pelvic compensation in patients with adult spinal deformity

BACKGROUND CONTEXTPrevious research has identified a specific subtype known as failure of pelvic compensation (FPC) in patients with adult spinal deformity (ASD). However, the criteria for assessing FPC remain inconsistent, and its impacts on spinal sagittal alignment and health-related quality-of-life (HRQoL) scores remain unclear. PURPOSETo propose a novel criterion for identifying FPC based on variations in spinopelvic alignment during the transition from the supine to upright position and to evaluate the effects of FPC on patients' spinal sagittal alignment and HRQoL scores. STUDY DESIGN/SETTINGRetrospective cross-sectional study. PATIENT SAMPLEPatients with ASD from a monocenter database. OUTCOME MEASURESRadiographic measures, including thoracic kyphosis (TK), lumbar lordosis (LL), sacral slope (SS), pelvic tilt, pelvic incidence (PI), and sagittal vertical axis (SVA), were measured on lateral whole-spine radiographs. LL and SS were also measured on reconstructed lumbar computed tomography images in the sagittal view taken in the supine position. The relative functional cross-sectional area (rFCSA) of paraspinal muscles was evaluated via lumbar magnetic resonance imaging. HRQoL measures, encompassing visual analog scale for back pain (VAS-BP), Oswestry Disability Index (ODI), and Scoliosis Research Society-22R (SRS-22R), were collected. METHODSA total of 154 patients were enrolled. Based on the calculated minimum detectable change of SS, FPC was defined as the change in SS of less than 3.4° between supine and upright positions. Patients were divided into 3 groups: sagittal balance with pelvic compensation (SI-PC), sagittal imbalance with pelvic compensation (SI-PC), and sagittal imbalance with failure of pelvic compensation (SI-FPC). Radiographic parameters and HRQoL scores were compared among the groups. RESULTSThirty-six patients were categorized into the SB-PC group, 87 into the SI-PC group, and 31 into the SI-FPC group. Patients with low PI and small paraspinal muscles rFCSA were more prone to experiencing FPC accompanied by severe sagittal imbalance. The SI-FPC group exhibited less TK and a larger SS than the SI-PC group exhibited and had a similar SVA as that of the SI-PC group. Additionally, they displayed worse VAS-BP, ODI, SRS-function, and SRS-22 total scores than the SB-PC group displayed. CONCLUSIONSIn patients with ASD, an inherently low pelvic compensatory reserve and a high fatty infiltration in paraspinal muscles are pivotal factors contributing to FPC. Compared with SI-PC patients, SI-FPC patients demonstrate a thoracic-dominant compensatory pattern for sagittal malalignment. In addition, these patients experienced more severe pain and functional decline than the SB-PC patients experienced.

AI-CPG: Adaptive Imitated Central Pattern Generators for Bipedal Locomotion Learned Through Reinforced Reflex Neural Networks

AI-CPG: Adaptive Imitated Central Pattern Generators for Bipedal Locomotion Learned Through Reinforced Reflex Neural Networks

LMI-based State Feedback Control of the Underactuated InertiaWheel Inverted Pendulum to the Unstable Upright Position

LMI-based State Feedback Control of the Underactuated InertiaWheel Inverted Pendulum to the Unstable Upright Position

Learning Advanced Locomotion for Quadrupedal Robots: A Distributed Multi-Agent Reinforcement Learning Framework with Riemannian Motion Policies

Recent advancements in quadrupedal robotics have explored the motor potential of these machines beyond simple walking, enabling highly dynamic skills such as jumping, backflips, and even bipedal locomotion. While reinforcement learning has demonstrated excellent performance in this domain, it often relies on complex reward function tuning and prolonged training times, and the interpretability is not satisfactory. Riemannian motion policies, a reactive control method, excel in handling highly dynamic systems but are generally limited to fully actuated systems, making their application to underactuated quadrupedal robots challenging. To address these limitations, we propose a novel framework that treats each leg of a quadrupedal robot as an intelligent agent and employs multi-agent reinforcement learning to coordinate the motion of all four legs. This decomposition satisfies the conditions for utilizing Riemannian motion policies and eliminates the need for complex reward functions, simplifying the learning process for high-level motion modalities. Our simulation experiments demonstrate that the proposed method enables quadrupedal robots to learn stable locomotion using three, two, or even a single leg, offering advantages in training speed, success rate, and stability compared to traditional approaches, and better interpretability. This research explores the possibility of developing more efficient and adaptable control policies for quadrupedal robots.

Correlation between Acetabular Anteversion with a False-Profile View and Spinopelvic Parameters in Adult Spinal Deformity after Long-Segment Corrective Spinal Surgery.

Studies describing the relationship between the hip and spine have reported that corrective spinal surgery for adult spinal deformity (ASD) affects the orientation of the acetabulum. However, the extent to which spinal correction in ASD affects acetabular anteversion in the standing position is unclear, especially after total hip arthroplasty, for which dislocation is a concern. The purpose of this study was to evaluate changes in anterior acetabular coverage in the upright position due to extensive correction surgery for ASD. Thirty-six consecutive patients who had undergone spinal corrective surgery from the thoracolumbar region to the pelvis were enrolled and evaluated. The ventral-central-acetabular (VCA) angle and anterior acetabular head index (AAHI) were measured with a false-profile view to evaluate the relationship between acetabular anteversion in the standing position and spinopelvic parameters before and after surgery. The spinopelvic parameters measured included thoracic kyphosis, pelvic incidence, pelvic tilt (PT), sacral slope, lumbar lordosis (LL), sagittal vertical axis, and global tilt. The VCA angle and AAHI were significantly increased after spinal deformity correction (p<0.001). The changes in LL and PT were correlated with the VCA angle (LL: right, ρ=0.56; left, ρ=0.55, p<0.001; PT: right, ρ=-0.59; left, ρ=-0.64, p<0.001) and AAHI (LL: right, ρ=0.51; left, ρ=0.58, p<0.01; PT: right, ρ=-0.52; left, ρ=-0.59, p<0.01), respectively. Linear regression analysis revealed that a 10° increase in LL results in 1.4°-1.9° and 1.6%-2% increases in the VCA angle and AAHI, respectively. Surgical correction for ASD significantly affects sagittal spinopelvic parameters, resulting in increased acetabular anteversion. The anterior coverage of the acetabulum in the postoperative standing position could be predicted with the intraoperatively measured LL, and evaluation using a false-profile was considered useful for treating ASD, particularly in patients after total hip arthroplasty.

Effect of Acute Dietary Nitrate Supplementation on the Changes in Calf Venous Volume during Postural Change and Skeletal Muscle Pump Activity in Healthy Young Adults.

Dietary nitrate (NO3-) supplementation is known to enhance nitric oxide (NO) activity and acts as a vasodilator. In this randomized crossover study, we investigated the effect of inorganic NO3- supplementation on the changes in calf venous volume during postural change and subsequent skeletal muscle pump activity. Fifteen healthy young adults were assigned to receive beetroot juice (BRJ) or a NO3--depleted control beverage (prune juice: CON). Two hours after beverage consumption, the changes in the right calf volume during postural change from supine to upright and a subsequent right tiptoe maneuver were measured using venous occlusion plethysmography. The increase in calf volume from the supine to upright position (total venous volume [VV]) and the decrease in calf volume during the right tiptoe maneuver (venous ejection volume [Ve]) were calculated. Plasma NO3- concentration was higher in the BRJ group than in the CON group 2 h after beverage intake (p < 0.05). However, VV and Ve did not differ between CON and BRJ. These results suggest that acute intake of BRJ may enhance NO activity via the NO3- → nitrite → NO pathway but does not change calf venous pooling due to a postural change or the calf venous return due to skeletal muscle pump activity in healthy young adults.

OS CARACTERES SEMIOLOGICOS DA DOENÇA VENOSA CRÔNICA

Chronic venous insufficiency is mostly idiopathic in nature and, in these cases, is called primary insufficiency. Another large part of cases of venous insufficiency is a consequence of a sequelae of DVT, in which case the venous insufficiency is called secondary. The striking clinical characteristics of venous insufficiency include: a feeling of tiredness or pain in the legs and edema that worsen in na upright position, more evident in the afternoon. Symptoms improve with elevation of the limb. Late changes in venous insufficiency include skin hyperpigmentation, lipodermatosclerosis and venous ulcers. The diagnosis is clinical and can be confirmed using color Doppler ultrasound. All patients with venous insufficiency should be treated by applying elastic stockings or compression bandages, in addition to elevating the limb three to four times a day, plantar flexion exercises and skin care. Venous ulcers should be treated using the same general measures recommended for chronic venous insufficiency, in addition to local wound care, such as dressing changes and debridement of devitalized tissues. The use of systemic antibiotic therapy is only foreseen in the presence of na active infection.

Supported Standing and Supported Stepping Devices for Children with Non-Ambulant Cerebral Palsy: An Interdependence and F-Words Focus.

Children functioning at Gross Motor Function Classification System (GMFCS) levels IV-V cannot maintain an aligned standing position or take steps without support. Upright positioning and mobility devices have psycho-social significance for these children and their families, enhancing use of vision, communication, functioning and emotional well-being. Standers and supported stepping devices facilitate opportunities for biomechanical loading, potentially helping to build and maintain muscle and bone integrity, and they promote physical development. However, families are often required to choose between these two devices for their young child. This study aims to synthesize evidence for use and benefits of both supported standing and stepping devices through the lens of two contemporary theoretical frameworks to support clinical reasoning and implementation. The F-words for childhood development (functioning, family, fitness, fun, friends, future) and the interdependence-Human Activity Assistive Technology (iHAAT) models were combined to illustrate the complex interactions between the child, family, caregivers, peers and contextual factors when implementing standing and stepping devices with children at GMFCS levels IV and V. Supported standing and stepping devices provide complementary benefits, and both may be necessary starting at 9-15 months. We propose they both be included ON-Time, along with other age-appropriate positioning and mobility devices, to promote more equitable developmental opportunities for children with non-ambulant cerebral palsy.

Assessing the impact of early progressive mobilization on moderate-to-severe traumatic brain injury: a randomized controlled trial.

Traumatic brain injury (TBI) is a major cause of neurodisability worldwide, with notably high disability rates among moderately severe TBI cases. Extensive previous research emphasizes the critical need for early initiation of rehabilitation interventions for these cases. However, the optimal timing and methodology of early mobilization in TBI remain to be conclusively determined. Therefore, we explored the impact of early progressive mobilization (EPM) protocols on the functional outcomes of ICU-admitted patients with moderate to severe TBI. This randomized controlled trial was conducted at a trauma ICU of a medical center; 65 patients were randomly assigned to either the EPM group or the early progressive upright positioning (EPUP) group. The EPM group received early out-of-bed mobilization therapy within seven days after injury, while the EPUP group underwent early in-bed upright position rehabilitation. The primary outcome was the Perme ICU Mobility Score and secondary outcomes included Functional Independence Measure motor domain (FIM-motor) score, phase angle (PhA), skeletal muscle index (SMI), the length of stay in the intensive care unit (ICU), and duration of ventilation. Among 65 randomized patients, 33 were assigned to EPM and 32 to EPUP group. The EPM group significantly outperformed the EPUP group in the Perme ICU Mobility and FIM-motor scores, with a notably shorter ICU stay by 5.9days (p < 0.001) and ventilation duration by 6.7days (p = 0.001). However, no significant differences were observed in PhAs. The early progressive out-of-bed mobilization protocol can enhance mobility and functional outcomes and shorten ICU stay and ventilation duration of patients with moderate-to-severe TBI. Our study's results support further investigation of EPM through larger, randomized clinical trials. Clinical trial registration ClinicalTrials.gov NCT04810273 . Registered 13 March 2021.

Adaptive Gait Acquisition through Learning Dynamic Stimulus Instinct of Bipedal Robot.

Standard alternating leg motions serve as the foundation for simple bipedal gaits, and the effectiveness of the fixed stimulus signal has been proved in recent studies. However, in order to address perturbations and imbalances, robots require more dynamic gaits. In this paper, we introduce dynamic stimulus signals together with a bipedal locomotion policy into reinforcement learning (RL). Through the learned stimulus frequency policy, we induce the bipedal robot to obtain both three-dimensional (3D) locomotion and an adaptive gait under disturbance without relying on an explicit and model-based gait in both the training stage and deployment. In addition, a set of specialized reward functions focusing on reliable frequency reflections is used in our framework to ensure correspondence between locomotion features and the dynamic stimulus. Moreover, we demonstrate efficient sim-to-real transfer, making a bipedal robot called BITeno achieve robust locomotion and disturbance resistance, even in extreme situations of foot sliding in the real world. In detail, under a sudden change in torso velocity of -1.2 m/s in 0.65 s, the recovery time is within 1.5-2.0 s.

Evaluation of Salivary Parameters and Oral Health Status in Periodontally Healthy Subjects and Chronic Periodontitis Subjects

Introduction: Periodontal disease is a chronic disease of the oral cavity that consists of a group of inflammatory disorders affecting the supporting structures of the dentition. Saliva can be used to predict the early onset of periodontitis. Several investigations have been carried out to evaluate the salivary chemical compounds that lead to the destruction and/or protection of periodontal tissues. The present study aimed to assess and compare salivary parameters and oral health status in periodontally healthy and chronic generalised periodontitis patients. Materials and Methods: This is an in vivo study designed to compare salivary parameters (albumin, urea, total proteins, amylase, glucose and pH) of unstimulated saliva and oral health status of periodontally healthy subjects (n = 65) and chronic generalised periodontitis subjects (n = 65). Human whole unstimulated saliva was collected by spitting method with the subject seated in an upright position after refraining from oral intake for 2 h before saliva collection. Approximately 5 mL of saliva was collected and stored in graduated saliva-collecting vials and refrigerated at 4°C for 1 h. The samples were centrifuged at 2800 rpm for 10 min, and the supernatant was separated from the substrate and stored at 20°C. Next, the sample was defrosted at room temperature and centrifuged at 3000 rpm. The supernatant was separated again to determine the concentrations of glucose, amylase, urea, total protein and albumin using the respective kits and analysed using an automated analyser. Salivary pH was estimated electrometrically with the help of a pH meter. Results: A significant association was found between salivary parameters (amylase and albumin total proteins) and clinical parameters (plaque index [PI], gingival index) [GI], probing depth and calculus index in generalised chronic periodontitis subjects when compared to periodontally healthy subjects. Conclusion: The increase in salivary parameters (amylase, total proteins and albumin) was statistically significant except for salivary glucose and urea (statistically non-significant) in generalised chronic periodontitis subjects compared to the healthy subjects. As the clinical parameters (probing depth, loss of attachment, PI, GI, calculus index and decay missing filled teeth) in periodontitis subjects increased, the salivary parameters also increased, suggesting a linear relationship between the generalised chronic periodontitis and salivary parameters (total proteins, albumin and amylase).

Impact of professional dance training on characteristics of postural sway.

The stability of human upright posture determines the range and dynamics of movements performed. Consequently, the repertoire and quality of the movements performed by a dancer are mainly determined by the efficiency of postural control. This is of particular importance in professional dance training that should focus on shaping optimal movement‑posture interaction. To get a deeper insight into this problem, the impact of the training on postural sway characteristics during quiet stance was analyzed in 16 female students in the seventh grade of a ballet school and compared with the size‑ and age‑matched group of secondary school students. Center of pressure trajectories were recorded for 25.6 s while standing quiet with eyes open (EO) and then with eyes closed (EC). The assessment of postural control was based on novel normalized sway parameters including sway vector (SV), sway anteroposterior (AP) and mediolateral (ML) directional indices (DIAP and DIML), and sway ratios (SRAP and SRML). The results document a significant contribution of vision to postural stability control in ballet students, which seems to compensate for training‑related changes in joint mobility and altered activity ranges of the legs' muscles. In the control group standing with EC, SV amplitude increased only by 18% whereas in the ballet students tested in the same conditions, the increase exceeded 72%. Under full control of standing posture (EO test), the training‑related increase of leg muscle forces allows dancers to maintain balance with lesser effort as documented here by 21% reduced SRAP. Additionally, the dancers while tested with their EC exhibited a 12% increase in the anteroposterior sway with a concomitant reduction of the mediolateral sway. The resulting changes in the postural control asymmetry were documented by both DIAP/DIML and SV azimuth. In conclusion, our novel analysis of postural sway seems a useful tool in monitoring the effects of training as well as the proper course of postural control development in children and adolescents.

The semiotic phenomenology of inverse alteroception

Abstract Alteroception is the virtual experience of another person’s bodily movement centered in the perspective of the other person. In face-to-face interactions, human beings tend to assume a special mode of alteroception by mutually but tacitly recognizing that ‘your right is on my left and your left is on my right’. Researchers of neonatal cognition and early childhood development describe this mode of alteroception as “reverse” or “inverted”. Inverse alteroception goes beyond mirror-image mimesis to chiastic (crisscrossing) mimesis in acts of intersubjective sense-making; but the cognitive and cultural affordances of this inverse reciprocal ability are largely untreated in the literature. I argue that this unique aspect of human phenomenology deserves closer attention since it enables a broader palette of diagrammatic contrasts that extend far beyond face-to-face interaction. In this paper, I apply insights from Peircean and Greimasian semiotics to argue that salient features of the human lifeworld originate from imaginative mappings of inverse alteroception onto other domains. From diagrams of gesture space and contemporary visual design to the structures of the Proscenium stage, from historic heraldry to Aristotle’s logical square of oppositions and beyond, many visual/spatial designs and their reciprocal interaction with human experience are linked to this ability – an ability that owes its origins, in turn, to the evolution of upright posture.

Reactive Gait Composition With Stability: Dynamic Walking Amidst Static and Moving Obstacles

Abstract This paper presents a modular approach to motion planning with provable stability guarantees for robots that move through changing environments via periodic locomotion behaviors. We focus on dynamic walkers as a paradigm for such systems, although the tools developed in this paper can be used to support general compositional approaches to robot motion planning with dynamic movement primitives (DMPs). By formulating the planning process as a switching system with multiple equilibria (SSME), we prove that the system's evolution remains within explicitly characterized trapping regions in the state space under suitable constraints on the frequency of switching among the DMPs. These conditions encapsulate the low-level stability limitations in a form that can be easily communicated to the planner. Furthermore, we show how the available primitives can be safely composed online in a receding horizon manner to enable the robot to react to moving obstacles. The proposed framework can be applied in a wide class of 3D bipedal walking models, and offers a modular approach for integrating readily available low-level locomotion control and high-level planning methods.