NASA Automated Rendezvous and Capture Review. Executive summary

In support of the Cargo Transfer Vehicle (CTV) Definition Studies in FY-92, the Advanced Program Development division of the Office of Space Flight at NASA Headquarters conducted an evaluation and review of the United States capabilities and state-of-the-art in Automated Rendezvous and Capture (AR&C). This review was held in Williamsburg, Virginia on 19-21 Nov. 1991 and included over 120 attendees from U.S. government organizations, industries, and universities. One hundred abstracts were submitted to the organizing committee for consideration. Forty-two were selected for presentation. The review was structured to include five technical sessions. Forty-two papers addressed topics in the five categories below: (1) hardware systems and components; (2) software systems; (3) integrated systems; (4) operations; and (5) supporting infrastructure

Development and validation of biomechanical models to quantify horse back forces at the walk in three horse breeds

Therapeutic horseback riding is a common component of physical therapy programs. Quantification of the horse back forces will provide vital information to match therapeutic riders with equine partners. To meet this medical need, a model to quantify the horse back forces from ground reaction forces was developed to test the hypothesis that the forces transferred to a static weight on the horse’s back can be predicted given horse breed and weight. Simultaneous, real time kinetic, kinematic, and back force data on a static weight were collected from 7 adult horses: 3 thoroughbreds, 3 quarter horses, and 1 paso fino. An integrated system consisting of a force platform, an active motion detection system and wireless force transducers were used. Data was collected from a minimum of four successful trials from all horses at a walk (1.3-2.0 m/s). Inverse dynamic analysis was used to calculate the fore and hind limb joint forces to the shoulder and hip, taking into consideration all 4 limbs’ motion per stride cycle. Virtual segments were created to model the equine back as a series of springs and dampers and joined to the limbs. Calculated forces from the inverse dynamics analysis were then input to the spring-damper model sequentially and at the same frequency as data collection. The energy absorption coefficients were derived by aligning the model output forces of the fore- and hind limb data with measured back forces. Horse back forces were simulated with different coefficients for each breed, and specifically for each horse. . Simulated results had a significant positive correlation (r = 0.81±0.04, p \u3c0.001) with forces measured directly on the back. The data from this investigation will contribute to mechanisms to predict forces experienced by the rider during horse motion to advance the science of therapeutic riding

Comparison of knee loading during walking via musculoskeletal modelling using marker-based and IMU-based approaches

openThe current thesis is the result of the candidate's work over a six-month period with the assistance of the supervisor and co-supervisors, thanks to the collaboration between the Human Movement Bioengineering Laboratory Research group at the University of Padova (Italy) and the Human Movement Biomechanics Research group at KU Leuven (Belgium). Gait analysis, at a clinical level, is a diagnostic test with multiple potentials, in particular in identifying functional limitations related to a pathological path. Three-dimensional motion capture is now consolidated as an approach for human movement research studies and consists of a set of very precise measurements, the latter are processed by biomechanical models, and curves relating to the kinematics and indirect dynamics, i.e., the joint angles and the relative forces and moments, can be obtained. These results are considered fully reliable and based on these curves it is decided how to intervene on the specific subject to make the path as less pathological as possible. However, the use of wearable sensors (IMUs) consisting of accelerometers, gyroscopes, and magnetic sensors for gait analysis, has increased in the last decade due to the low production costs, portability, and small size that have allowed for studies in everyday life conditions. Inertial capture (InCap) systems have become an appealing alternative to 3D Motion Capture (MoCap) systems due to the ability of inertial measurement units (IMUs) to estimate the orientation of 3D sensors and segments. Musculoskeletal modelling and simulation provide the ideal framework to examine quantities in silico that cannot be measured in vivo, such as musculoskeletal loading, muscle forces and joint contact forces. The specific software used in this study is Opensim: an open-source software that allows modelling, analysis, and simulation of the musculoskeletal system. The aim of this thesis is to compare a marker-based musculoskeletal modelling approach with an IMUs-based one, in terms of kinematics, dynamics, and muscle activations. In particular, the project will focus on knee loading, using an existing musculoskeletal model of the lower limb. The current project was organized as follows: first, the results for the MoCap approach were obtained, following a specific workflow that used the COMAK IK tool and the COMAK algorithm to get the secondary knee kinematics, muscle activations, and knee contact forces. Where COMAK is a modified static optimization algorithm that solves for muscle activations and secondary kinematics to obtain measured primary DOF accelerations while minimizing muscle activation. Then these results were used to make a comparison with those obtained by the inertial-based approach, with the attempt to use as little information as possible from markers while estimating kinematics from IMU data using an OpenSim toolbox called OpenSense. Afterward, in order to promote an approach more independent from the constraints of a laboratory, the Zero Moment Point (ZMP) method was used to estimate the center of pressure position of the measured ground reaction forces (GRFs), and a specific Matlab code was implemented to improve this estimation. Using the measured GRFs with the new CoPs, the results of Inverse Dynamics, muscle activations, and finally knee loading were calculated and compared to the MoCap results. The final step was to conduct a statistical analysis to compare the two approaches and emphasize the importance of using IMUs for gait analysis, particularly to study knee mechanics

15-01 Effect of Cycling Skills on Bicycle Safety and Comfort Associated with Bicycle Infrastructure and Environment

This study seeks to improve the methodology for determining the relationship between cycling dynamic performance and roadway environment characteristics across different bicyclists’ skill levels. To achieve the goal of this study, an Instrumented Probe Bicycle (IPB) equipped with various sensors was built. A naturalistic field experiment, including intersections, roundabout, alignment changes, and different road surface conditions, was conducted. Two self-reported questionnaires were used in order to obtain each participant’s skill level as well as perception on the level of cycling comfortability. The Cycling Comfortability Index (CCI) was derived from the probabilistic outcome of an Ordered Probit Model, which describes the relationship between bicycle dynamics and level of comfortability. Fault Tree Analysis (FTA), a technique widely used to measure the risk of a fault event occurrence in a system, was employed to integrate mobility and comfortability. The estimation results showed that the probability of a fault event occurrence is related to the bicyclist’s experience level, incline of the roadway, and quality of the road surface. It was also found that cycling comfort level is significantly affected by the average y-axis acceleration and the mean absolute deviation of the z-axis velocity. The results of this study have practical implications for improving bicyclist perceptions on comfortability and for increasing safety for cyclists

An investigation into the efficacy of kinematics and kinetics method for stride-characteristic measurements of horses trotting on a treadmill

The aim of this study was to investigate the validity of stride characteristic measurements taken from the sternum by means of an Optical Motion Capture System (OMCS) and an Inertia Measurement Unit (IMU), in comparison with OMCS hoof markers. Measurements were taken from sound horses of a range of breeds, trotting at self-selected speeds on a treadmill (OMCS N=15; IMU N=4). Hoof marker trajectories were compared in terms of dorsoventral position (pZ), craniocaudal velocity (vX) and dorsoventral velocity (vZ). Contra-laterally coupled limbs were compared at beginning and end of stance according to vX. A Girth Marker (GM) placed over the sternum was used to identify beginning and end of stance of each diagonal using dorsoventral acceleration (aZ) and dorsoventral velocity (vZ) respectively. These were compared with hoof marker vX. GM aZ and vZ were then validated against the same measurements taken by an IMU measuring at the same time from the same location. No significant difference (p < 0.05) was found by ANOVA between hoof marker trajectories pZ, vX or vZ at beginning or end of stance. No significant difference was found by t-test or ICC between contralaterally coupled limbs at beginning or end of stance. GM aZ and vZ could be used to identify beginning and end of stance for each diagonal without significant difference from hoof vX timings according to t-test and ICC. OMCS GM and IMU did not differ in terms of velocity (peak or trough timing or amplitude, or absolute difference: peak minus trough), or acceleration peak timing, trough timing or trough amplitude according to t-test or ICC. However, OMCS GM and IMU differed significantly in terms of acceleration peak amplitude (p = .01, ICC = 0.46) and absolute difference (p = .04, ICC = 0.66). The sternum can be used as a site to collect data providing accurate information on beginning or end of stance of horses with no advanced placement of contralaterally coupled limbs, whilst trotting at self selected speeds on a treadmill. Temporal acceleration data, and temporal or amplitudal velocity data are sufficient to identify beginning and end of stance from the sternum using an IMU. Amplitudal acceleration data from an IMU should be further investigated before assumed valid under these conditions

Kinematics of the equine axial skeleton during aqua-treadmill exercise

Equine aqua-treadmills are increasingly applied within the industry for rehabilitation from injury and training. Research into aqua-treadmill exercise has been increasing yet there are still opportunities to further quantify the effect of water depth on locomotion in order to optimise aqua-treadmill protocols to see improved rehabilitation from injury or to exercise horses more effectively for their chosen discipline. Much of the current aqua-treadmill literature focusses on the effects of water on locomotory parameters in walk, thus providing an opportunity for investigation into the impact of water at trot. Trot is the favoured gait for effective quantification of lameness and symmetry studies so it was anticipated that there may be opportunities to make comparisons to previously published overground data. Effective schooling of horses overground includes training aids, such as side reins, to constructively develop a horse’s way of going and often to assist the horse in maintaining concentration. This provided a further opportunity for investigation into the use of side reins during aqua-treadmill exercise. This project therefore, aimed to quantify the effect of increasing water depths on pelvic and withers movement of horses trotting on an aquatreadmill and to analyse the impact the use of side reins has on these movements. Seventeen sound horses were habituated to aqua-treadmill exercise and subjected to one of two exercise protocols where data were collected either by optical motion capture (Qualisys©) or an inertial sensor system (Xsens©). The exercise protocol involved trotting on the aqua-treadmill at four increasing water depths, that of the third phalanx (P3), mid fetlock, mid third metacarpal (MC3), and mid carpus. Markers for optical motion capture were located on the poll, withers (T4/T5), mid thorax (T13), tuber sacrale, left and right tuber coxae, left and right tuber ischia. Inertial sensors were located on the poll, withers (T4/T5), mid thorax (T13), lumbar vertebrae (L4), tuber sacrale, left and right tuber coxae, and top of the tail (1st coccygeal vertebrae). Data were cut into strides with accelerations double integrated to generate displacement amplitudes, both vertical and mediolateral, for statistical testing. Pitch and roll data from the inertial sensors was also extracted and processed for analysis. Data were processed using custom written scripts (Matlab®) and repeated measures ANOVAs were performed throughout to test for significance with post hoc analysis where appropriate. Water depth was found to have a significant effect on vertical displacement amplitudes of the pelvis and withers with vertical displacements increasing with increasing water depth, and a greater displacement in the pelvis than the withers. Minimum and maximum positions of the pelvis and withers were found to decrease and increase accordingly with increasing water depth, with minimum values decreasing significantly indicating an increase in limb compression during stance. Maximum vertical positions also increased significantly indicating greater maximum lift out of the water as a result of the increased compression. Water depth had no effect on symmetry of horses trotting on an aquatreadmill and no effect on pitch amplitudes. Vertical displacements, pitch and symmetry were not altered with the addition of side reins, suggesting that the adoption of a different head and neck position whilst reaching comparable displacement amplitudes encourages further engagement of back muscles possibly providing stimulus for building greater strength through muscular development. Water depth was found to have no effect on mediolateral displacements of the pelvis or withers but with the withers exhibiting larger mediolateral displacements than the pelvis at lower water depths but reducing to an amount comparable to the pelvis at deeper depths suggesting that deeper water provides a stabilising effect on the front end of the horse. Side reins had no effect on mediolateral displacement amplitudes or on roll amplitudes. Mediolateral flexions of the spine were not affected by water depth or side reins, suggesting that the horse can be worked harder at greater water depths without over stressing the mediolateral capabilities of the spine. Vertical displacements of the pelvis were significantly increased when trotting on the aquatreadmill in a very low depth of water compared to measurements overground but this effect was not seen in the withers suggesting the front end of the horse can efficiently compensate for water depth by flexing at the carpus, although larger pitch amplitudes were reported at the withers suggesting a change in head and neck position to create a ‘jump up’ over the water. Side reins were found to decrease vertical displacement amplitudes in the withers overground but trotting on the aqua-treadmill in a small amount of water counteracted this effect suggesting that the addition of water may counteract a ‘downhill’ effect seen in horses wearing side reins overground. This project suggests that the aqua-treadmill is beneficial at increasing the workload for the horse that may possibly have a corresponding effect of increasing muscle mass, strength and condition, but without detrimental effects to cranial-caudal or mediolateral symmetry patterns and that side reins have a potential benefit in supporting these locomotory patterns. Knowledge of this primary scientific data will better assist professionals working with aqua-treadmills to more effectively benefit the horses with which they work. There is, however, an opportunity for further longitudinal research to further support the effective application of the aqua-treadmill as a tool for rehabilitation and training