scholarly journals Obtaining Natural Sit-to-Stand Motion with a Biomimetic Controller for Powered Knee Prostheses

2017 ◽  
Vol 2017 ◽  
pp. 1-6 ◽  
Author(s):  
Molei Wu ◽  
Md Rejwanul Haque ◽  
Xiangrong Shen
Keyword(s):  
Control Structure ◽  
Power Delivery ◽  
Knee Prostheses ◽  
Control Approach ◽  
Prosthetic Joints ◽  
Sit To Stand ◽  
Standing Up ◽  
Common Activity ◽  
Healthy Side ◽  
Two Phases

Standing up from a seated position is a common activity in people’s daily life. However, for transfemoral (i.e., above-knee) amputees fitted with traditional passive prostheses, the sit-to-stand (STS) transition is highly challenging, due to the inability of the prosthetic joints in generating torque and power output. In this paper, the authors present a new STS control approach for powered lower limb prostheses, which is able to regulate the power delivery of the prosthetic knee joint to obtain natural STS motion similar to that displayed by healthy subjects. Mimicking the dynamic behavior of the knee in the STS, a unified control structure provides the desired control actions by combining an impedance function with a time-based ramp-up function. The former provides the gradual energy release behavior desired in the rising phase, while the latter provides the gradual energy injection behavior desired in the loading phase. This simple and intuitive control structure automates the transition between the two phases, eliminating the need for explicit phase transition and facilitating the implementation in powered prostheses. Human testing results demonstrated that this new control approach is able to generate a natural standing-up motion, which is well coordinated with the user’s healthy-side motion in the STS process.

Walking-Stair Climbing Control for Powered Knee Prostheses

2016 ◽  
Author(s):  
Molei Wu ◽  
Xiangrong Shen
Keyword(s):  
Impedance Control ◽  
Knee Prosthesis ◽  
Stair Climbing ◽  
Knee Joints ◽  
Knee Prostheses ◽  
Control Approach ◽  
Prosthetic Joints ◽  
Real Time Measurement ◽  
Human Subject Testing ◽  
Finite State

Recent progresses in powered lower-limb prostheses have the potential of enabling amputee users to conduct energetically demanding locomotive tasks, which are usually beyond the capability of traditional unpowered prostheses. Realizing such potential, however, requires responsive and reliable control of the power provided by prosthetic joints. In this paper, an integrated walking-stair climbing control approach is presented for transfemoral prostheses with powered knee joints. Leveraging the similarities between walking and stair climbing, this new approach adopts the general finite-state impedance control framework. Furthermore, important modifications are introduced to model the biomechanical characteristics that are beyond the capability of standard impedance control. The transition between the walking and stair-climbing modes is triggered through the real-time measurement of the spatial orientation of the user’s thigh, which provides a reliable indicator of the user’s intention of making such transition. This new control approach has been implemented on a powered knee prosthesis, and its effectiveness was demonstrated in human subject testing.

scholarly journals Sit-to-Stand Control of Powered Knee Prostheses

2017 ◽  
Author(s):  
Molei Wu ◽  
Md Rejwanul Haque ◽  
Xiangrong Shen
Keyword(s):  
Knee Prosthesis ◽  
Single Equation ◽  
The Body ◽  
Knee Prostheses ◽  
Major Barrier ◽  
Control Approach ◽  
Biomechanical Behavior ◽  
Sit To Stand ◽  
Reaction Forces ◽  
Prosthesis Control

Standing from a seated position is a common, yet dynamically challenging task. Due to the vertical ascent of the body center of gravity, sit-to-stand (STS) transition requires high torque output from the knee. As a result, STS transition poses a major barrier to the mobility of individuals with lower-limb issues, including the transfemoral (TF, also known as above-knee) amputees. A study showed that unilateral TF amputees suffer from high asymmetry in ground reaction forces (53∼69%) and knee moments (110∼124%), while the asymmetry for healthy controls is less than 7% [1]. Note that, although a powered TF prosthesis (Power Knee™) was used in this study, it generated resistance in the STS and thus produced similar results as the passive devices. The inability of existing prostheses in generating knee torque and regulating the torque delivery in the STS seriously affects the mobility of TF amputees in their daily life. Motivated by this issue, researchers have developed numerous powered TF prostheses (e.g., Vanderbilt powered TF prostheses [2]). These devices are able to generate torque and power for challenging tasks such as STS transition. Making full use of such capability, however, requires an effective controller. Currently, walking control for powered prostheses has been well established, but STS control is much less investigated. Varol et al. developed a multi-mode TF prosthesis controller, in which STS is treated as a transitional motion between sitting and standing states [2]. However, no details were provided on the rationale of the STS controller structure or the determination of the control parameters. In this paper, a new prosthesis control approach is presented, which regulates the power and torque delivery in the STS process. Inspired by the biomechanical behavior of the knee in the STS motion, the new controller provides two desired functions (gradual loading of the knee at the beginning, and automatic adjustment of the knee torque according to motion progress) with a single equation. Combined with a simple yet reliable triggering condition, the proposed control approach is able to provide natural STS motion for the powered knee prosthesis users.

Transition from Sitting to Standing after Trans-Femoral Amputation

2005 ◽  
Vol 29 (2) ◽  
pp. 139-151 ◽  
Author(s):  
Helena Burger ◽  
Jernej Kuželički ◽  
Črt Marinček
Keyword(s):  
Daily Activity ◽  
Healthy Subjects ◽  
The Body ◽  
Body Motion ◽  
Prosthetic Foot ◽  
Ankle Joints ◽  
Standing Up ◽  
Robot Wrist ◽  
Healthy Side ◽  
In Trans

Standing up is an important and common daily activity. It is essential for independence and a prerequisite for walking. Many elderly and many subjects with impairments have problems with transition from sitting to standing. The aim of the present study was to determine whether there was any difference between the characteristics of standing up in trans-femoral amputees and healthy subjects. Five young trans-femoral amputees and five healthy subjects were included in the study. They were asked to stand up. The body motion was recorded using an Optotrak contactless optical system. The force and moment vectors exerted on the seat were recorded by a JR3 six-axis robot wrist sensor. The force under the feet was recorded by two AMTI force plates. The trans-femoral amputees were found to stand up more slowly than the healthy subjects. The angles of the hip, knee, and ankle joints on the amputated side were different from the angles on the healthy side or in the healthy subjects. There was also a great difference in loading between the healthy and the prosthetic foot. It can be concluded that there are differences in standing up between the trans-femoral amputees and the healthy subjects. These differences may indicate a reason for problems many elderly trans-femoral amputees face when standing up.

scholarly journals The Effect of Ageing on the Standing Up Movement Analysed using the Capacity, Reserve, Movement Objectives, and Compensation (CaReMoOC) Framework

2020 ◽  
Author(s):  
Eline van der Kruk ◽  
Anne K Silverman ◽  
Peter Reilly ◽  
Anthony M J Bull
Keyword(s):  
Motor Control ◽  
Current Knowledge ◽  
Control Strategies ◽  
The Elderly ◽  
Mobility Limitations ◽  
Future Studies ◽  
Sit To Stand ◽  
Age Related ◽  
Standing Up ◽  
Movement Compensation

In healthy ageing, capacity declines in the neural, muscular, and skeletal systems, and each system decline has its effect on the execution of complex motor tasks. This decline in capacity can result in the inability to stand up (sit-to-stand, sit-to-walk), which is a key movement for independence. The mechanisms leading to mobility limitations or inabilities are complex, overlapping, and interdependent and the complementary fields of biomechanics, motor control, and physiology need to be combined to understand these mechanisms. The aim of this review is to provide an overview of the current knowledge of age-related compensation in standing up and to consider the limitations of these results when analysing standing up in daily life using the Capacity, Reserve, Movement Objectives, and Compensation (CaReMoOC) framework that combines biomechanics, motor control, and physiology. A literature search was performed in the search engine Scopus, using the keywords and their synonyms: strateg*(approach, technique, way) AND, sit-to-walk OR sit-to-stand OR rise (raise, arise, stand, stand-up) AND chair (seat). Inclusion criteria were: biomechanics or motor control on sit-to-stand or sit-to-walk in healthy and/or frail adults (<60y) and elderly (>60y), and/or osteoarthritis patients as a specific case of ageing related decline. The review shows that movement compensations in standing up manifest as changes in planned trajectory (Compensation by Selection) and in muscle recruitment (Compensation by Reorganisation). However, as most studies in the literature typically use standardized experimental protocols where movement compensation is restricted, these studies cannot be directly translated to functional tasks, such as the mobility of the elderly in their homes, communities, and clinic. Compensation must be included in future studies in order to facilitate clinical translation. Specifically, future studies in the standing up task should 1) determine the effect of varying arm use strategies (e.g., armrests, knees, chair, cane) on trunk and both lower limb and upper limb joint loading, 2) analyse control strategies in elderly people, 3) determine the biomechanical implications of asymmetry, and 4) incorporate assessments of age-related physical and neural decline as well as changes in psychological priorities.

scholarly journals Fractional-Order Sliding Mode Control of Overhead Cranes   

2020 ◽  
Vol 31 (1) ◽  
pp. 68-76
Keyword(s):  
Sliding Mode Control ◽  
Fractional Order ◽  
Closed Loop ◽  
Control Structure ◽  
Adaptive System ◽  
Sliding Mode ◽  
Lyapunov Theory ◽  
Closed Loop System ◽  
Control Approach ◽  
Mode Control

We constitute a control system for overhead crane with simultaneous motion of trolley and payload hoist to destinations and suppression of payload swing. Controller core made by sliding mode control (SMC) assures the robustness. This control structure is inflexible since using fixed gains. For overcoming this weakness, we integrate variable fractional-order derivative into SMC that leads to an adaptive system with adjustable parameters. We use Mittag–Leffler stability, an enhanced version of Lyapunov theory, to analyze the convergence of closed-loop system. Applying the controller to a practical crane shows the efficiency of proposed control approach. The controller works well and keeps the output responses consistent despite the large variation of crane parameters.

Within-Person Dynamics of Older Adults’ Physical Activity, Sedentary Behavior, and Sit-to-Stand Transitions

2018 ◽  
Vol 1 (4) ◽  
pp. 159-164 ◽  
Author(s):  
Jaclyn P. Maher ◽  
David E. Conroy
Keyword(s):  
Physical Activity ◽  
Older Adults ◽  
Sedentary Behavior ◽  
Multilevel Modeling ◽  
Daily Physical Activity ◽  
Daily Step ◽  
Step Counts ◽  
Sit To Stand ◽  
Naturally Occurring ◽  
Standing Up

This study evaluated how older adults’ daily physical activity covaries with naturally occurring variation in both the duration and patterning of daily sedentary behavior. Older adults (n = 95) wore activPAL3 monitors for 15 consecutive days. Multilevel modeling regressed daily step counts on the frequency of sit-to-stand transitions and the duration of sedentary behavior. At the person-level, older adults who sat less (b = −14.31, p < .001) and stood up more frequently (b = 41.08, p = .01) took more steps on average. At the within-person level, older adults took more steps on days when they sat less than usual (b = −8.29, p < .001) and stood up more frequently than usual (b = 52.75, p < .001). Older adults’ daily physical activity may be influenced by interrupting sedentary behavior more frequently as well as reducing total sedentary behavior. It may be easier to monitor the frequency of discrete behaviors, like standing up, than it is to monitor the duration of continuous behaviors (e.g., walking, sitting).

A Review on Human Motion Prediction in Sit to Stand and Lifting Tasks

2016 ◽  
Author(s):  
Erik A. Chumacero-Polanco ◽  
James Yang
Keyword(s):  
Humanoid Robots ◽  
Human Motion ◽  
Motion Prediction ◽  
Articulated Figures ◽  
Sit To Stand ◽  
Human Motion Prediction ◽  
Human Movements ◽  
Standing Up ◽  
Prediction And Simulation ◽  
And Control

Human-like motion prediction and simulation is an important task with many applications in fields such as occupational-biomechanics, ergonomics in industrial engineering, study of biomechanical systems, prevention of musculoskeletal disorders, computer-graphics animation of articulated figures, prosthesis and exoskeletons design as well as design and control of humanoid robots, among others. In an effort to get biomechanical insight in many human movements, extensive work has been conducted over the last decades on human-motion prediction of tasks as: walking, running, jumping, standing from a chair, reaching and lifting. This literature review is focused on the STS motion and the LLM. STS is defined as the process of rising from a chair to standing up position without losing stability balance, it is the most ubiquitous and torque-demanding daily labor and it is closely related to other capabilities of the human body. LLM is defined as the activity of raising a load, generally a box, from a low to a higher position while stability is maintained, this task produces a high number of incidences of low-back pain and injuries in many industrial and domestic activities. In order to predict STS and LLM, two methods have been identified: these are the OBMG method and the CBMG method.

Simulation-Based Unassisted Sit-to-Stand Motion Prediction for Healthy Young Individuals

2014 ◽  
Author(s):  
Burak Ozsoy ◽  
James Yang
Keyword(s):  
Experimental Studies ◽  
Three Dimensional ◽  
Bilateral Symmetry ◽  
Motion Prediction ◽  
Daily Lives ◽  
Joint Torques ◽  
Sit To Stand ◽  
Limb Injuries ◽  
Common Activity ◽  
Musculoskeletal Abnormalities

Sit-to-stand (STS) is a common activity in daily lives which requires relatively high joint torques and a robust coordination of lower and upper extremities with postural stability. Many elderly, people with lower limb injuries, and patients with neurological disorders or musculoskeletal abnormalities have difficulties in accomplishing this task. In contrast to the literature on numerous experimental studies of STS, there are limited studies that were carried out through simulations. In literature, mostly bilateral symmetry was assumed for STS tasks, however even for healthy people, it is more difficult to perform STS tasks with a perfect bilateral symmetry. The goal of this research is to develop a three-dimensional unassisted STS motion prediction formulation for healthy young individuals. Predicted results will be compared with experimental results found in literature for the validation of the proposed formulation.

Trajectory generator design based on the user's intentions for a CMC lower-limbs rehabilitation device

Robotica ◽  
2014 ◽  
Vol 34 (5) ◽  
pp. 1026-1041 ◽  
Author(s):  
L. Seddiki ◽  
K. Guelton ◽  
J. Zaytoon ◽  
H. Akdag
Keyword(s):  
Control Structure ◽  
Active Role ◽  
Lower Limbs ◽  
Level Control ◽  
Discrete State ◽  
Control Approach ◽  
High Level ◽  
Generator Design ◽  
Rehabilitation Exercises ◽  
Trajectory Generator

SUMMARYThis paper deals with the design of the control structure of a lower-limbs rehabilitation device in closed muscular chain called Sys-Reeduc. This control structure aims at providing a safe behavior to the user when performing rehabilitation exercises. It is based on two levels. The first level is concerned with the robust trajectory tracking of robotic device and has been the subject of previous studies. Nevertheless, it does not allow, by itself, the user to voluntarily drive the device. Therefore, a trajectory generator constituting the second level is presented in this paper to complete the whole control structure. This high-level control layer is described by a set of dedicated discrete state machines that provide the appropriate sequencing of elementary rehabilitation movements. These elementary movements are dynamically characterized so that clinician may choose the required trajectory parameters to adapt rehabilitation protocols and training to each individual. To realize a complete rehabilitation exercise, the sequence of elementary movements is triggered by thresholds relative to the measurement of the efforts applied by the user on the device. This allows the user to play an active role in its rehabilitation exercises and safely drive the machine at his/her own initiative. The design of the main exercises (isokinetic, isometric, and isotonic) used in the context of lower limbs rehabilitation is described, and simulation results illustrate the effectiveness of the proposed trajectory generator-based control approach.

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