1,721,014 research outputs found
Accurate Human Motion Estimation Using Inertia Measurement Units for Use in Biomechanical Analysis
Get PDFVision-based motion capture systems (MCSs) are often used as a way to create full-body virtual models of human beings, for applications ranging from movie Computer-Generated Imagery (CGI) to biomechanical analysis of human movements to medical purposes. However, vision-based MCS are often very expensive and require long and complicated preparation procedures. This study aimed to use inertial measurement units (IMUs), which are significantly more cost-effective and easier to use than visual-based MCSs, in order to create a motion capture system with accuracy comparable to that of visual motion capture systems. The IMUs used for the system include 3-axis gyroscopes, 3-axis accelerometers, and 3-axis magnetometers. A novel algorithm is introduced for orientation estimations which makes two position estimates���one using the gyroscope and one using a combination of the accelerometer and magnetometer���and an average is found between the two. Preliminary tests involving a subject performing shoulder abductions/adductions, elbow flexions/extensions, and hip flexions/extensions revealed low root-mean-squared error values and high correlation between joint angles calculated concurrently using the visual- and IMU-based motion capture systems. The ultimate goal of this application is to develop a graphical user interface (GUI) that can facilitate the accurate biomechanical analyses of the human and/or animal movement using kinematic data (e.g., 3D orientation) from low-cost and easy-to-use IMUs. Ultimately, the algorithm is expected to be made open-source, and this application will enable a more affordable, accessible, and portable biomechanics lab of human movement analysis for researchers and provide simple ways for clinicians to diagnose pathological movements of their patients
The Effect of the Toe Joint on Bipedal Walking
No full textBipedal robots are being developed to assist humans in various forms, including standalone robots and those integrated with human contacts, such as exo-suits and robotic prosthetic limbs. Understanding human-like movements is crucial in bipedal robot research, and the relatively understudied toe joint plays a significant role in walking. This study employs simulation methods and optimal control theory to investigate the impact of the toe joint on bipedal robot locomotion.
Using the direct collocation method, a simulation was conducted on a 9-link bipedal model with a toe joint and a 7-link model without a toe joint. The results showed that the 9-link model exhibited a wider stride length, faster walking speed, and lower objective function value. The analysis of the toe joint angle-torque graph indicated the influence of the toe joint in walking, leading to the determination of an optimal toe joint stiffness of 1.04 Nm/deg, suitable for practical implementation. Experimental optimal toe joint stiffness was validated using subject preference surveys. The results aligned with the optimal stiffness identified in the simulation. The toe joint-ankle joint power analysis further supported the optimal toe joint stiffness efficiency. However, statistical significance was limited due to the small subject sample size and incomplete experimental data. Future research aims to address these limitations by increasing the number of subjects and conducting comprehensive experiments to validate the optimal toe joint stiffness. Additionally, confirming the interaction between the ankle and toe joints identified in the experimental study will be explored.Maste
Environmental perception and joint trajectory generation for transfemoral prosthesis
No full textRecent wearable robot technology has made significant advancements aimed at enhancing the mobility of lower-limb amputees and ndividuals with walking disabilities. This technology is designed to facilitate smooth movement not only on level ground but also on stairs and ramp. However, previous studies have primarily focused on steady state of gait in environmental conditions, limiting the robot’s ability to provide appropriate assistance during transitions between different terrains. In this study, we integrate depth cameras and IMU sensors to perceive the environment using visual inertial odometry and elevation mapping, and a stride model to detect the user’s walking intentions during terrain changes. Additionally, we utilize the ProMPs (Probabilistic Movement Primitives) model to predict the walking trajectory during the swing phase considering the height of the stairs and the state of the user when transitioning from level ground to stairs.
Experimental results demonstrated that the proposed environmental perception model achieved over 95 % accuracy in outdoor environments. In the laboratory, the model accurately recognized the user’s intentions with more than 94 % accuracy for obstacles including curbs and stairs of various heights. For other environments, it recognized walking intentions with an accuracy of over 80 %. Moreover, the validation of the joint trajectory model through simulations showed success rates of 71.88 % and 97.92 % using actual and estimated thigh angles, respectively.
This research validates the potential of a model that accurately predicts walking intentions and provides appropriate trajectories for transfemoral prosthesis used in various terrains.Maste
Design of a Portable and Compact Gyroscopic Device for Hand Rehabilitation
Get PDFUser centered design is an apt process for developing assistive devices, as user needs
are given the utmost importance in this approach. On studying current, state of the art hand rehabilitation devices, it was inferred that there exists a need for a compact and portable hand rehabilitation device ��� one suitable for patients with adversely limited active range of motion of the hand. This thesis proposes a novel hand-held, portable device that is composed of a fully actuated rotor-gimbal assembly (US Patent Application: 62/413,130). The simultaneous motion of the rotor and gimbal results in a controlled gyroscopic torque that acts on the user���s hand. Based on the hand���s strength and mobility, the user may either synchronize the hand movement with that compelled by the device or restrict it. While the former results in the relaxation of muscles, the latter can potentially increase muscle co-ordination and muscle strength. The target specifications of the device were determined through interviews with personnel specialized in the field of hand rehabilitation. A working principle of the device was then established via a proof-of-concept model and mathematical simulations, which were further used to firm up the design parameters. The dynamic analysis of the device was then conducted to attest the structural integrity. Also, the range of forces imposed by the device on the hand were evaluated to be within safe measures through simulation and consecutive comparison with existing literature. Future work includes fabricating the final device and evaluating its performance via experiments with human subjects.
hand were evaluated to be within safe measures through simulation and consecutive comparison with existing literature. Future work includes fabricating the final device and evaluating its performance via experiments with human subjects
Quantification of the human postural control system to perturbations
No full textHuman standing posture is inherently unstable. The postural control system (PCS), which maintains standing posture, is composed of the sensory, musculoskeletal, and central nervous systems. Together these systems integrate sensory afferents and generate appropriate motor efferents to adjust posture. The PCS maintains the body center of mass (COM) with respect to the base of support while constantly resisting destabilizing forces from internal and external perturbations. To assess the human PCS, postural sway during quiet standing or in response to external perturbation have frequently been examined descriptively. Minimal work has been done to understand and quantify the robustness of the PCS to perturbations. Further, there have been some previous attempts to assess the dynamical systems aspects of the PCS or time evolutionary properties of postural sway. However those techniques can only provide summary information about the PCS characteristics; they cannot provide specific information about or recreate the actual sway behavior.
This dissertation consists of two parts: part I, the development of two novel methods to assess the human PCS and, part II, the application of these methods. In study 1, a systematic method for analyzing the human PCS during perturbed stance was developed. A mild impulsive perturbation that subjects can easily experience in their daily lives was used. A measure of robustness of the PCS, 1/MaxSens that was based on the inverse of the sensitivity of the system, was introduced. 1/MaxSens successfully quantified the reduced robustness to external perturbations due to age-related degradation of the PCS. In study 2, a stochastic model was used to better understand the human PCS in terms of dynamical systems aspect. This methodology also has the advantage over previous methods in that the sway behavior is captured in a model that can be used to recreate the random oscillatory properties of the PCS. The invariant density which describes the long-term stationary behavior of the center of pressure (COP) was computed from a Markov chain model that was applied to postural sway data during quiet stance. In order to validate the Invariant Density Analysis (IDA), we applied the technique to COP data from different age groups. We found that older adults swayed farther from the centroid and in more stochastic and random manner than young adults.
In part II, the tools developed in part I were applied to both occupational and clinical situations. In study 3, 1/MaxSens and IDA were applied to a population of firefighters to investigate the effects of air bottle configuration (weight and size) and vision on the postural stability of firefighters. We found that both air bottle weight and loss of vision, but not size of air bottle, significantly decreased balance performance and increased fall risk. In study 4, IDA was applied to data collected on 444 community-dwelling elderly adults from the MOBILIZE Boston Study. Four out of five IDA parameters were able to successfully differentiate recurrent fallers from non-fallers, while only five out of 30 more common descriptive and stochastic COP measures could distinguish the two groups. Fall history and the IDA parameter of entropy were found to be significant risk factors for falls.
This research proposed a new measure for the PCS robustness (1/MaxSens) and a new technique for quantifying the dynamical systems aspect of the PCS (IDA). These new PCS analysis techniques provide easy and effective ways to assess the PCS in occupational and clinical environments.Item withdrawn by Mark Zulauf ([email protected]) on 2010-12-02T22:35:20Z
Item was in collections:
University of Illinois Theses & Dissertations (ID: 1)
No. of bitstreams: 3
dissertation_v06_final_dept.pdf: 2067466 bytes, checksum: b0f5376a0926919309d4761c63fe9485 (MD5)
hur_pilwon.doc: 1881088 bytes, checksum: efe52ddfb8cf30b932a502d9c8ce41dd (MD5)
hur_pilwon.pdf: 2067466 bytes, checksum: b0f5376a0926919309d4761c63fe9485 (MD5)Made available in DSpace on 2011-01-21T22:46:47Z (GMT). No. of bitstreams: 2
hur_pilwon.pdf: 2070124 bytes, checksum: e7825b27cd622eb503462e60d9ee58a8 (MD5)
license.txt: 4057 bytes, checksum: 7c9f8ae0d3cfc17b8030fd3166347438 (MD5)Item marked as restricted to the 'UIUC Users [automated]' Group (id=2) by William Ingram ([email protected]) on 2011-01-21T22:48:20Z
Item is restricted until 2013-01-21T22:47:37ZItem reinstated by Sarah Shreeves ([email protected]) on 2013-01-22T11:00:26Z
Item was in collections:
University of Illinois Dissertations and Theses (ID: 204)
Dissertations and Theses - Mechanical Science and Engineering (ID: 675)
No. of bitstreams: 3
hur_pilwon.pdf.txt: 193863 bytes, checksum: 87aa1cdea52e160a874c29c7526d945f (MD5)
hur_pilwon.pdf: 2070124 bytes, checksum: e7825b27cd622eb503462e60d9ee58a8 (MD5)
license.txt: 4057 bytes, checksum: 7c9f8ae0d3cfc17b8030fd3166347438 (MD5)Item released from any restrictions by Sarah Shreeves ([email protected]) on 2013-01-22T11:00:26
EXPLORING HOW FUNCTIONAL IMPROVEMENT IS RELATED TO INTERACTION BETWEEN CHILDREN WITH CEREBRAL PALSY AND HORSES DURING HIPPOTHERAPY: A PILOT STUDY
Get PDFHippotherapy (HPOT) refers to how occupational therapy, physical therapy and speech-language pathology professionals use evidence-based practice and clinical reasoning in the purposeful manipulation of equine movement as a therapy tool. There is limited scientific, evidence-based research to support the effects of HPOT, hence there is a need for such equine-assisted therapy for individuals with cerebral palsy (CP). This pilot study evaluated the impact of HPOT between children with CP and horses in terms of kinetics. The participants were 4 children with CP between 3 and 12 years of age. Eight 20-minute sessions of HPOT treatments were conducted, with data collection on days 1, 4 and 8. Functional mobility was measured using the Timed Up and Go test for 3 subjects and 10-Meter walk test for 1 subject, all performed before and after HPOT on data collection days. Six Inertial Measurement Units (IMU) devices were used to measure the acceleration of the children and horses during the HPOT. The IMU sensor data was analyzed using fast Fourier transformation (FFT) and cross-correlation with a time shift. The study is to determine the rationale behind the success of HPOT.
The results show that as the therapy progressed, the subjects demonstrated a significant decrease in the time required to complete the functional mobility tests and improved in the ability to synchronize with the horse���s movement in the up-and-down direction. In conclusion, this study provides evidence that HPOT can be leading to improved functional mobility for children with CP as evidenced by the positive interaction between the movements of the children with CP and the horse. Future work includes analyzing data in other planes of movement and evaluating causality between improved functional mobility and positive interaction
J Electromyogr Kinesiol
Get PDFEffect of wearing gloves on timely muscle reaction to stabilize handle perturbation was investigated. Thirteen adults gripped a horizontal overhead handle to which an upward force was applied at a random time. Muscle reaction time, integrated EMGs for eight muscles, and handle displacement were compared among three glove conditions affecting the coefficient of friction (COF=0.32, 0.50, and 0.74 for the polyester glove, bare hand, and latex glove, respectively). Lower COF increased the integrated EMGs and handle displacement until stabilization of the perturbed handle. The low-friction glove resulted in 16% (p=.01) greater muscular effort and 20% (p=.002) greater handle displacement, compared to the high-friction glove. Muscle reaction time was not influenced by glove condition. Cutaneous sensation and reflex eliciting forearm muscle activity appear to play an important role in detecting and responding to the perturbation initially, while the forearm and latissimus dorsi muscles primarily contribute to stabilizing the perturbed handle compared to other shoulder and upper arm muscles. Therefore, low-friction gloves, cutaneous sensory dysfunction, and weakened forearm and latissimus dorsi muscles may jeopardize persons' ability to stabilize a grip of a handle after perturbation.T42 OH008672/OH/NIOSH CDC HHS/United State
Alternative Measures of Toe Trajectory More Accurately Predict the Probability of Tripping than Minimum Toe Clearance
Get PDFTripping is responsible for a large percentage of falls. Minimum toe clearance (MTC) during the swing phase of gait is commonly used to infer the probability of tripping (POT). However, there is limited empirical evidence to support the relationship between these two variables, and other measures of toe trajectory may better predict POT than MTC. The goals of this study were to: 1) quantify the relationship between MTC and POT; and 2) explore alternative measures of toe trajectory that may predict POT more accurately than MTC.
POT was estimated by comparing the distribution of obstacles measured along heavily-used, paved sidewalks on a university campus to the toe trajectory of 40 young adults obtained while walking over an obstacle-free walkway in a research laboratory. POT exhibited a curvilinear relationship with MTC, and regression equations were established to predict POT from MTC. POT was more accurately predicted when using virtual points on the bottom of the anterior edge of the shoe to determine MTC, compared to using a physical marker located on top of the toes to determine MTC. POT was also more accurately predicted when using a new measure of toe trajectory (the area below 40mm and above the toe trajectory, normalized by the swing length), compared to just MTC. These are the first empirical results supporting a relationship between MTC and POT. These results may improve the ability to identify risk factors that influence POT, and aid in developing interventions to reduce POT
Robotic Surface Finishing of Curved Surfaces: Real-Time Identification of Surface Profile and Control
Get PDFThis thesis introduces a complete design framework for robotic surface finishing of curved surfaces. The system setup is subdivided into three key components: Real-time surface registration is accomplished by employing a proximity laser sensor mounted on the robot end-effector. The proximity sensor measurements coupled with the robot kinematics is employed to derive the coordinates of the projection points. The entire set of projection points is combined to form a grid upon which the surface normal and its normal profile are reconstructed. This surface normal profile description allows us to generate trajectories for both motion and force control. The trajectory generation is a variation of the time-scaling method to incorporate local surface normal information. Instead of using every local normal to form a trajectory, the trajectory is generated based on the local normal of a few sampled projection points. The local normal is estimated from the two consecutive sampled projection points to form the trajectory at the current time step while the end-effector is traveling between them. Therefore, a continuous stream of position goals is generated that would orient the robot end-effector to the local normal of the surface. Finally, this trajectory and a force set point are inputs to the force and position control loop that was synthesized using the simultaneous force and position control strategy; this strategy is based on the robot kinematics model using the product of exponential formula. Therefore the control strategy is robust to system uncertainties.
The integrated robotic surface finishing system consists of a UR5 robot and a custom end-effector that includes a force/torque sensor, electromechanical sander, and the laser sensor. Robot Operating System (ROS) is utilized for real-time implementation, which will enable easy migration of the developed tools to other industrial robots. The effectiveness of the strategy is evaluated by conducting a number of experiments for flat and curved surfaces that includes force regulation and surface finishing on wooden surfaces; a representative sample of results is presented and discussed to validate the proposed approach
Dynamics and Control of a Planar Tensegrity Robot Arm
Get PDFTensegrity structures have been used in the field of engineering and architecture over the last half century to build static load-bearing structures. These structures are built out of a network of rigid bars and elastic strings which are connected to each other at their ends. The primary advantage of these structures is that the elements are under axial loading only which dramatically reduces their minimal mass.
Recently tensegrity structures have gained interest in the Space community which is in need of lightweight robot designs for planetary exploration and spacecraft maintenance. This research work aims to address some of the challenges in tensegrity research. Firstly, this work presents minimal mass design of a planar tensegrity robot arm and compares with a conventional design. Then the robot’s dynamics is formulated using Lagrange’s method. Finally, optimal control theory is utilized to solve two control problems - stabilization in the presence of disturbance and noise and robust tracking of a desirable trajectory
- …
