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.

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 and Control of a New Tendon-Driven Exoskeletal Lower Body Power Assistive Device

2005 ◽  
Author(s):  
Kyoungchul Kong ◽  
Doyoung Jeon
Keyword(s):  
The Elderly ◽  
Body Motion ◽  
Joint Torque ◽  
Assistive Device ◽  
Lower Body ◽  
Wearable Robot ◽  
Standing Up ◽  
Wearable Exoskeleton ◽  
And Control ◽  
Lower Body Power

Recently the exoskeletal power assistive equipment which is a kind of wearable robot has been widely developed to help the human body motion. For the elderly people and patients, however, some limits exist due to the weight and volume of the equipments. As a feasible solution, a tendon-driven exoskeletal power assistive device for the lower body, and caster walker are proposed in this research. Since the caster walker carries the heavy items, the weight and volume of the wearable exoskeleton are minimized. The fuzzy control is used to generate the joint torque required to assist motions such as sitting, standing and walking. Experiments were performed for several motions and the EMG sensors were used to measure the magnitude of assistance. When the motion of sitting down and standing up was compared with and without wearing the proposed device, the 27% assistance was acquired.

Biomechanical Model of the Press Handstand in Gymnastics

1988 ◽  
Vol 4 (4) ◽  
pp. 326-341 ◽  
Author(s):  
Spiros G. Prassas
Keyword(s):  
Shoulder Joint ◽  
Joint Angle ◽  
Wrist Joint ◽  
Center Of Mass ◽  
Biomechanical Model ◽  
Joint Torque ◽  
Joint Torques ◽  
Skilled Performance ◽  
The Press ◽  
Line Passing

A biomechanical model of the press handstand was developed to evaluate and predict the shoulder joint torque requirements as well as the motion of a gymnast’s center of mass (CM) from an initial to a final (handstand) position. Five press handstands executed by gymnasts of differing abilities were filmed and analyzed. The results were compared to the predicted parameters of simulated presses. It was found that execution of the skill with fewer fluctuations in trunk and lower extremities angular velocity—a characteristic of skilled performance—required smoother and at times larger shoulder joint torques. Reduction of the hip joint angle by only 5 or 10° did not substantially reduce the shoulder joint torque requirements. Regarding CM motion, it was found that during performance the CM continuously elevated and remained close to a vertical line passing through the center of the wrist joint. All gymnasts, however, were found to be leaning slightly backward during the first part of the movement and slightly forward during the later phases. Modifications in wrist joint angle required to maintain each gymnast’s CM precisely above the center of the wrist joint were investigated.

Muscle Synergy Analysis Between Young and Elderly People in Standing-Up Motion

2013 ◽  
Vol 25 (6) ◽  
pp. 1038-1049 ◽  
Author(s):  
Qi An ◽  
◽  
Yusuke Ikemoto ◽  
Hajime Asama
Keyword(s):  
Motor Function ◽  
Older Persons ◽  
The Elderly ◽  
Joint Torque ◽  
Daily Activities ◽  
Muscle Synergy ◽  
Elderly Persons ◽  
Muscle Coordination ◽  
Important Data ◽  
Standing Up

Standing up is fundamental to daily activities of the elderly. It is necessary both to enhance muscle strength and to strengthen muscle coordination for improvement of their motor function. In this paper, we extract important data related to muscle coordination, called synergy, to perform standing motion by young and elderly participants. The contribution of muscle synergy to body kinematics is calculated through neural networks that estimate joint torque and body kinematics. To explain deficient motor function in elderly persons, extracted synergy is classified into 4 clusters based on how synergy contribute to body kinematics. Cluster analysis explains that elderly participants have weaker synergy than young persons in bending their backs to generate momentum. Compared to younger persons, older persons require additional muscle coordination to stabilize posture after standing-up in order to avoid falling.

Analyzing and Reducing Energy Usage in a Humanoid Robot During Standing Up and Sitting Down Tasks

2016 ◽  
Vol 13 (04) ◽  
pp. 1650014 ◽  
Author(s):  
Ercan Elibol ◽  
Juan Calderon ◽  
Martin Llofriu ◽  
Wilfrido Moreno ◽  
Alfredo Weitzenfeld
Keyword(s):  
Humanoid Robot ◽  
Center Of Pressure ◽  
Center Of Mass ◽  
Electrical Power ◽  
Joint Torque ◽  
Q Learning ◽  
Current Usage ◽  
Standing Up ◽  
Joint Velocity ◽  
Joint Acceleration

The aim of this paper is to reduce the energy consumption of a humanoid by analyzing electrical power as input to the robot and mechanical power as output. The analysis considers motor dynamics during standing up and sitting down tasks. The motion tasks of the humanoid are described in terms of joint position, joint velocity, joint acceleration, joint torque, center of mass (CoM) and center of pressure (CoP). To reduce the complexity of the robot analysis, the humanoid is modeled as a planar robot with four links and three joints. The humanoid robot learns to reduce the overall motion torque by applying Q-Learning in a simulated model. The resulting motions are evaluated on a physical NAO humanoid robot during standing up and sitting down tasks and then contrasted to a pre-programmed task in the NAO. The stand up and sit down motions are analyzed for individual joint current usage, power demand, torque, angular velocity, acceleration, CoM and CoP locations. The overall result is improved energy efficiency between 25–30% when compared to the pre-programmed NAO stand up and sit down motion task.

Static force and tipover stability analysis of an assistive device for paraplegics

2021 ◽  
pp. 095441192110369
Author(s):  
Ahmad Abdullah ◽  
Zareena Kausar ◽  
Haroon Raza ◽  
Abdullah Siddiqui ◽  
Neelum Yousaf ◽  
...  
Keyword(s):  
Center Of Mass ◽  
Standing Position ◽  
Assistive Device ◽  
Static Force ◽  
Sitting Position ◽  
Force Analysis ◽  
End Effector ◽  
Kinematics Modeling ◽  
Cord Injury ◽  
Analysis Of Stability

Stability plays a vital role in any robotic system. Its significance increases in systems related to health and medicine. For rehabilitation devices meant for Spinal Cord Injury (SCI) patients, stability is crucial and key element in ensuring patient safety and the usefulness of the devices. In this study, kinematics, force analysis, and the static tip-over stability of a device for rehabilitation of paraplegic patients is discussed. Kinematics modeling and static force analysis provide critical information about position and loading at different points on the device. Force-Angle Stability Criterion is used to find the static tip-over stability of the device while the patient is on board the device. The Criterion relies on the support boundary, tip-over mode axes, and the Center of Mass (COM) of the complete system. The Criterion is sensitive to the COM position and therefore is more suitable for the application. The linear actuator mounted on the device causes the end effector of the device to move. The patient, strapped with the end effector, in turn moves from sitting position to standing position. The study focuses on the analysis of stability based on changing COM during this motion. The results verify that although the system is well within the stability bounds, it is more stable as it moves from sitting position to standing position.

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