Design of a Passive Gravity-Balanced Assistive Device for Sit-to-Stand Tasks

2005 ◽  
Vol 128 (5) ◽  
pp. 1122-1129 ◽  
Author(s):  
Abbas Fattah ◽  
Sunil K. Agrawal ◽  
Glenn Catlin ◽  
John Hamnett
Keyword(s):  
Center Of Mass ◽  
Total Potential Energy ◽  
Assistive Device ◽  
Clinical Testing ◽  
Assist Device ◽  
Joint Torques ◽  
Total Potential ◽  
Sit To Stand ◽  
Standing Up ◽  
Functional Task

A sit-to-stand assist device can serve the needs of people suffering from muscle weakness due to age or disabilities that make sit-to-stand a difficult functional task. The objective of this paper is to design a passive gravity-balancing assist device for sit-to-stand motion. In our study, it has been shown that the contribution to the joint torques by the gravitational torque is dominant during sit-to-stand motion. On the basis of this result, a gravity balanced assistive device is proposed. This passive device uses a hybrid method to identify the center-of-mass of the system using auxiliary parallelograms first. Next, appropriate springs are connected to the device to make the total potential energy of the system due to the gravity and the springs constant during standing up. A demonstration prototype with the underlying principles was fabricated to test the feasibility of the proposed design. The prototype showed gravity balancing and was tested by the authors. This prototype will be modified appropriately for clinical testing.

Design of a Gravity-Balanced Assistive Device for Sit-to-Stand Tasks

2004 ◽  
Author(s):  
Abbas Fattah ◽  
Sunil K. Agrawal ◽  
John Fitzgibbons
Keyword(s):  
Center Of Mass ◽  
The Elderly ◽  
Joint Torque ◽  
Assistive Device ◽  
Inverse Dynamic ◽  
Joint Torques ◽  
Gravitational Torque ◽  
Total Potential ◽  
Cord Injury ◽  
Standing Up

The joint torques in hip, knee and ankle are computed using inverse dynamic model during standing up for a paraplegic patient. The joint torque comprises the dynamical torque due to the inertia forces, and a passive torque due to the muscles and gravitational torque. It has been observed that the contribution to the joint torques by the gravitational torque is dominant. On the basis of this result, a gravity balanced assistive device is proposed for the elderly and impaired people such as spinal cord injury and paraplegic patients. This passive device uses a hybrid method to identify the center of mass of the system using auxiliary parallelograms first. Next appropriate springs are connected to the device to vanish the total potential energy of the system due to the gravity during standing up. A prototype with the underlying principles is currently being fabricated at the University of Delaware.

Static Balancing of Spatial Six-Degree-of-Freedom Parallel Mechanisms With Revolute Actuators

1998 ◽  
Author(s):  
Jiegao Wang ◽  
Clément M. Gosselin
Keyword(s):  
Potential Energy ◽  
Center Of Mass ◽  
Total Potential Energy ◽  
Degree Of Freedom ◽  
Gravitational Potential Energy ◽  
Parallel Mechanisms ◽  
Static Balancing ◽  
Total Potential ◽  
Global Center ◽  
Six Degree Of Freedom

Abstract The static balancing of spatial six-degree-of-freedom parallel mechanisms or manipulators with revolute actuators is studied in this paper. Two static balancing methods, namely, using counterweights and using springs, are used. The first method leads to mechanisms with a stationary global center of mass while the second approach leads to mechanisms whose total potential energy (including the elastic potential energy stored in the springs as well as the gravitational potential energy) is constant. The position vector of the global center of mass and the total potential energy of the manipulator are first expressed as functions of the position and orientation of the platform. Then, conditions for static balancing are derived from the resulting expressions. Finally, examples are given in order to illustrate the design methodologies.

Muscle Forces and Their Contributions to Vertical and Horizontal Acceleration of the Center of Mass During Sit-to-Stand Transfer in Young, Healthy Adults

2016 ◽  
Vol 32 (5) ◽  
pp. 487-503 ◽  
Author(s):  
Elena J. Caruthers ◽  
Julie A. Thompson ◽  
Ajit M.W. Chaudhari ◽  
Laura C. Schmitt ◽  
Thomas M. Best ◽  
...  
Keyword(s):  
Muscle Force ◽  
Center Of Mass ◽  
Three Dimensional ◽  
Gluteus Maximus ◽  
Healthy Adults ◽  
Muscle Forces ◽  
Dynamic Simulations ◽  
Joint Torques ◽  
Main Contributor ◽  
Sit To Stand

Sit-to-stand transfer is a common task that is challenging for older adults and others with musculoskeletal impairments. Associated joint torques and muscle activations have been analyzed two-dimensionally, neglecting possible three-dimensional (3D) compensatory movements in those who struggle with sit-to-stand transfer. Furthermore, how muscles accelerate an individual up and off the chair remains unclear; such knowledge could inform rehabilitation strategies. We examined muscle forces, muscleinduced accelerations, and interlimb muscle force differences during sit-to-stand transfer in young, healthy adults. Dynamic simulations were created using a custom 3D musculoskeletal model; static optimization and induced acceleration analysis were used to determine muscle forces and their induced accelerations, respectively. The gluteus maximus generated the largest force (2009.07 ± 277.31 N) and was a main contributor to forward acceleration of the center of mass (COM) (0.62 ± 0.18 m/s2), while the quadriceps opposed it. The soleus was a main contributor to upward (2.56 ± 0.74 m/s2) and forward acceleration of the COM (0.62 ± 0.33 m/s2). Interlimb muscle force differences were observed, demonstrating lower limb symmetry cannot be assumed during this task, even in healthy adults. These findings establish a baseline from which deficits and compensatory strategies in relevant populations (eg, elderly, osteoarthritis) can be identified.

Improving sit-to-stand transition by the saddle-assistive device in the spinal cord injury: A case study

2021 ◽  
pp. 095441192110033
Author(s):  
Akbar Hojjati Najafabadi ◽  
Saeid Amini ◽  
Farzam Farahmand
Keyword(s):  
Spinal Cord ◽  
Spinal Cord Injury ◽  
Lower Limb ◽  
Reaction Force ◽  
Assistive Device ◽  
Limb Weakness ◽  
Sit To Stand ◽  
Lower Limb Weakness ◽  
Wide Range ◽  
Cord Injury

Physical problems caused by fractures, aging, stroke, and accidents can reduce foot power; these, in the long term, can dwindle the muscles of the waist, thighs, and legs. These conditions provide the basis for the invalidism of the harmed people. In this study, a saddle-walker was designed and evaluated to help people suffering from spinal cord injury and patients with lower limb weakness. This S-AD works based on body weight support against the previously report designs. This saddle-walker consisted of a non-powered four-wheel walker helping to walk and a powered mechanism for the sit-to-stand (STS) transfer. A set of experiments were done on the STS in the use of the standard walker and the saddle-assistive device(S-AD). A comparison of the results showed that this device could reduce the vertical ground reaction force (GRF) of the legs up to 70%. Using this device could help a wide range of patients with lower limb weakness and SCI patients in changing from sitting to standing.

A simplified formulation of adhesion problems with elastic plates

2009 ◽  
Vol 465 (2107) ◽  
pp. 2217-2230 ◽  
Author(s):  
Carmel Majidi ◽  
George G. Adams
Keyword(s):  
Potential Energy ◽  
Contact Area ◽  
Contact Region ◽  
Bending Moment ◽  
Total Potential Energy ◽  
Work Of Adhesion ◽  
Contact Radius ◽  
Algebraic Complexity ◽  
Elastic Plates ◽  
Total Potential

The solution of adhesion problems with elastic plates generally involves solving a boundary-value problem with an assumed contact area. The contact region is then found by minimizing the total potential energy with respect to the contact area (i.e. the contact radius for the axisymmetric case). Such a procedure can be extremely long and tedious. Here, we show that the inclusion of adhesion is equivalent to specifying a discontinuous internal bending moment at the contact region boundary. The magnitude of this moment discontinuity is related to the work of adhesion and flexural rigidity of the plate. Such a formulation can greatly reduce the algebraic complexity of solving these problems. It is noted that the related plate contact problems without adhesion can also be solved by minimizing the total potential energy. However, it has long been recognized that it is mathematically more efficient to find the contact area by specifying a continuous internal bending moment at the boundary of the contact region. Thus, our moment discontinuity method can be considered to be a generalization of that procedure which is applicable for problems with adhesion.

Vibration Analysis of the Continuous Truss Girder Bridge by the Finite Truss Elements

2011 ◽  
Vol 268-270 ◽  
pp. 557-560
Author(s):  
Shi Ruo Yang
Keyword(s):  
Composite System ◽  
Elastic System ◽  
Total Potential Energy ◽  
Time Varying ◽  
Girder Bridges ◽  
Total Potential ◽  
Vibration Responses ◽  
Pass Through ◽  
Girder Bridge ◽  
Set Up

The train and the continuous truss girder bridge are coupled together as one composite system. Truss girder bridge is idealized as an assemblage of finite truss element. The equations of the train and truss girder bridges time varying system are set up by using the principle of total potential energy with stationary value in elastic system dynamics and the“set-in-right-position”rule for forming structural matrices. This method is more convenient than the finite elements. The vibration responses of the train and bridge are calculated when the the passenger trains pass through a continuous truss girder bridge at speeds of 90km/h and 120km/h The results show that the passenger train can pass it safely and comfortably

Application of Sit-To-Stand Assistive Device Based on Hip Support

2021 ◽  
Vol 14 ◽  
Author(s):  
Huaiqiang Zhang ◽  
Qiang Xue ◽  
Shuo Yang ◽  
Tongtong Wang ◽  
Binwei Zhou
Keyword(s):  
Lower Limb ◽  
Independent Living ◽  
Structural Characteristics ◽  
Assistive Devices ◽  
Assistive Device ◽  
Technology Application ◽  
Assist Devices ◽  
Advantages And Disadvantages ◽  
Sit To Stand

Background: Completing the transition from a sitting position to a standing position is a basic skill in people’s daily lives and is crucial for independent living. Lower limb dysfunction will bring many inconveniences into a person’s life and greatly affect their quality of life. Patients with lower limb dysfunction are a specialized group, and nursing problems for this group are becoming increasingly serious. Helping patients with lower limb dysfunction restore their lower limb mobility or assisting them to walk is a social problem necessary to be solved. Objective: : To review the recent sit-to-stand assistive devices based on hip support, classify them systematically and introduce their characteristics, including the mechanisms and the types of patients for which such mechanisms are applicable; to help patients with lower limb dysfunction or doctors (therapists) understand and choose a reasonable sit-to-stand assist device based on hip support. Methods: This paper summarizes literatures and patents about sit-to-stand assistive devices. From the aspects of structural characteristics, drive type and support modes based on the hip and applications situation, the advantages and disadvantages of the typical sit-to-stand assist devices are represented. Results: Current and future development trends on the structural characteristics, drive type and support modes based on the hip and applications situation of sit-to-stand assist devices are discussed to improve the humanization, modularization and applicability of sit-to-stand assist devices. Conclusion: Sit-to-stand assistive devices based on hip support can help patients improve the quality of their life, assist patients carrying out rehabilitation training, and delay the decline of lower limb function. However, the existing sit-to-stand assistive devices based on hip support need further improvement in the aspects of motion mechanism, new technology application and ergonomics design.

Wheelchair-Portable Patient Lift

2018 ◽  
Vol 13 (1) ◽  
Author(s):  
Yoshikazu Mori ◽  
Akihiko Nakada
Keyword(s):  
Nursing Home ◽  
Flat Surface ◽  
Center Of Mass ◽  
Experimental Results ◽  
Assistive Device ◽  
Leaving Home ◽  
Sliding Mechanism ◽  
Small Force ◽  
Weight Carrying ◽  
Sufficient Strength

A patient lift is an assistive device for patients who lack sufficient strength or muscle control to be transferred between a wheelchair and a toilet or other places. Patient lifts of two kinds are commonly used: overhead lifts and mobile lifts. Nevertheless, because of its size and weight, carrying even a mobile lift with a wheelchair is difficult when leaving home. This study examined a novel portable patient lift that is small and light, sufficient to be carried using a wheelchair in a folded state. It is compact, light, and portable because it has no actuator. Moreover, its operation is simple. It is useful not only at home or in a nursing home but on any flat surface during daily excursions and activities, even in a conventional lavatory. A caregiver can transfer a user with a small force because this lift has a sliding mechanism that brings the fulcrum closer to the patient's center of mass. Experimental results underscore the effectiveness of the proposed patient lift.

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