Implementation of robotic ankle–foot orthosis with an impedance-based assist-as-needed control strategy

2021 ◽  
pp. 1-40
Author(s):  
Bing Chen ◽  
Bin Zi ◽  
Bin Zhou ◽  
Zhengyu Wang
Keyword(s):  
Level Control ◽  
Ankle Foot Orthosis ◽  
Low Level ◽  
Ankle Impedance ◽  
Torque Generation ◽  
Ankle Rehabilitation ◽  
Finite State ◽  
Proportional Derivative Controller ◽  
High Level ◽  
Foot Orthosis

Abstract In this paper, a robotic ankle–foot orthosis (AFO) is developed for individuals with a paretic ankle, and an impedance-based assist-as-needed controller is designed for the robotic AFO to provide adaptive assistance. First, a description of the robotic AFO hardware design is presented. Next, the design of the finite state machine is introduced, followed by an introduction to the modelling of the robotic AFO. Additionally, the control of the robotic AFO is presented. An impedance-based high-level controller that is composed of an ankle impedance based torque generation controller and an impedance controller is designed for the high-level control. A compensated low-level controller that is composed of a braking controller and a proportional-derivative controller with a compensation part is designed for the low-level control. Finally, a pilot study is conducted, and the experimental results demonstrate that with the proposed control algorithm, the robotic AFO has the potential for ankle rehabilitation by providing adaptive assistance. In the assisted condition with a high level of assistance, reductions of 8% and 20.1% of the root mean square of the tibialis anterior and lateral soleus activities are observed, respectively.

Powered Ankle-Foot Prostheses: A Survey on Sensing Systems and Control Strategies

2019 ◽  
Author(s):  
Erik Chumacero-Polanco ◽  
James Yang
Keyword(s):  
Control Strategies ◽  
Level Control ◽  
Low Level ◽  
Kinetic Information ◽  
Sensing Systems ◽  
Systems And Control ◽  
Finite State ◽  
High Level ◽  
And Control

Abstract People who have suffered a transtibial amputation show diminished ambulation and impaired quality of life. Powered ankle foot prostheses (AFP) are used to recover some mobility of transtibial amputees (TTAs). Powered AFP is an emerging technology that has great potential to improve the quality of life of TTAs with important avenues for research and development in different fields. This paper presents a survey on sensing systems and control strategies applied to powered AFPs. Sensing kinematic and kinetic information in powered AFPs is critical for control. Ankle angle position is commonly obtained via potentiometers and encoders directly installed on the joint, velocities can be estimated using numerical differentiators, and accelerations are normally obtained via inertial measurement units (IMUs). On the other hand, kinetic information is usually obtained via strain gauges and torque sensors. On the other hand, control strategies are classified as high- and low-level control. The high-level control sets the torque or position references based on pattern generators, user’s intent of motion recognition, or finite-state machine. The low-level control usually consists of linear controllers that drive the ankle’s joint position, velocity, or torque to follow an imposed reference signal. The most widely used control strategy is the one based on finite-state machines for the high-level control combined with a proportional-derivative torque control for low-level. Most designs have been experimentally assessed with acceptable results in terms of walking speed. However, some drawbacks related to powered AFP’s weight and autonomy remain to be overcome. Future research should be focused on reducing powered AFP size and weight, increasing energy efficiency, and improving both the high- and the low-level controllers in terms of efficiency and performance.

A Robotic Ankle-Foot Orthosis for Daily-Life Assistance and Rehabilitation

2018 ◽  
Author(s):  
Md Rejwanul Haque ◽  
Hao Zheng ◽  
Saroj Thapa ◽  
Geza Kogler ◽  
Xiangrong Shen
Keyword(s):  
Daily Life ◽  
Human Movement ◽  
Gear Ratio ◽  
Assistive Device ◽  
Wearable Robot ◽  
Performance Goal ◽  
Natural Interaction ◽  
Ankle Foot Orthosis ◽  
Finite State ◽  
Foot Orthosis

The ankle plays an important role in human movement as it supplies the majority of energy to support an individual’s walking. In this paper, the authors present a robotic ankle-foot orthosis (RAFO), which is essentially a wearable robot that acts in parallel to the user’s biological ankle for motion assistance. Unlike most of the existing robotic ankle-foot ortheses, the RAFO in this paper is a compact and portable assistive device with full energy autonomy, which enables its use in a user’s daily life without the typical limitation associated with tethered operation. The primary performance goal in the design of the RAFO is to provide a torque capacity equivalent to 35% of a 75 kg healthy person’s maximum ankle torque in slow walking, while keeping the weight of the device less than 2 kg. To reach such goal, the orthotic joint is actuated with a compact flat motor coupled with a two-stage transmission that provides a total 200:1 gear ratio. Additionally, a novel two-degree-of-freedom (2-DOF) joint design is incorporated. In addition to the powered dorsiflexion – plantarflexion, the 2-DOF joint also allows passive inversion – eversion of the joint, which greatly improves the comfort in the prolonged wearing of the device. For the control of the powered joint, a finite-state, friction-compensated impedance controller is developed to provide natural interaction with the user and reliable triggering of the powered push-off in walking. A prototype of the RAFO has been fabricated and assembled, and preliminary results demonstrated its effectiveness in assisting the user’s locomotion in treadmill walking experiments.

Ankle-Foot Orthosis Function in Low-Level Myelomeningocele

1992 ◽  
Vol 12 (4) ◽  
pp. 578 ◽  
Author(s):  
M. G. Hullin ◽  
J. E. Robb ◽  
I. R. Loudon
Keyword(s):  
Ankle Foot Orthosis ◽  
Low Level ◽  
Foot Orthosis

Ankle Rehabilitation Device to Prevent Contracture Using a Pneumatic Balloon Actuator

2011 ◽  
Vol 5 (4) ◽  
pp. 538-543 ◽  
Author(s):  
Norihiko Saga ◽  
◽  
Naoki Saito ◽  
Jun-ya Nagase ◽  
Keyword(s):  
Transfer Mechanism ◽  
Drive System ◽  
Simple System ◽  
Power Transfer ◽  
Silicone Tube ◽  
Ankle Foot Orthosis ◽  
Medical Institutions ◽  
Ankle Rehabilitation ◽  
Tendon Drive ◽  
Foot Orthosis

Our proposed rehabilitation device to prevent contracture of the ankle is easy to produce, transport, and install at the time of use in places such as medical institutions. This device is intended for use by hemiplegic people. The ankle is moved when it is worn, preventing ankle contracture. It consists of a new tendon-drive system using a pneumatic balloon actuator, power transfer mechanism, and ankle foot orthosis. This new tendon drive system using a pneumatic balloon was developed as an actuator of this device. The system consists of a tendon and a silicone tube. Both ends of the tube are closed. The tube expands with the supplied air, which distends the silicone tube and thereby pulls the tendon. This simple system is both compact and powerful. Furthermore, its materials and structure make it light. This paper describes characteristics of this tendon drive system using a pneumatic balloon, along with its composition and operation as a rehabilitation device for preventing ankle contracture. Results of operation tests using the device are also presented.

Analysis and Control Design of a Hydro-Mechanical Hydraulic Hybrid Passenger Vehicle

2009 ◽  
Author(s):  
Teck Ping Sim ◽  
Perry Y. Li
Keyword(s):  
Control Systems ◽  
Torque Control ◽  
Mechanical Transmission ◽  
Control Analysis ◽  
Passenger Vehicle ◽  
Level Control ◽  
Analysis And Design ◽  
Low Level ◽  
Hydraulic Hybrid ◽  
High Level

This paper gives the dynamic analysis of a hydro-mechanical transmission (HMT) drive train with regeneration and independent wheel torque control of a hydraulic hybrid passenger vehicle. From this analysis, we formulate the HMT control system, which is made up of high, mid and low-level control systems. The high-level consists of a state of charge management and the mid-level translates the storage requirement specified by the high-level into desired internal speed and gear ratio to be executed by the low-level. In this paper we focus on the low-level control analysis and design, where the actuation authority to regulate the internal speed variable comes from either the engine (mode 1) or the hydraulic system (mode 2). Experimental studies show good tracking performance of the proposed control systems and enable our vehicle system to be driven in the proposed HMT architecture.

scholarly journals Low-Level Control of 3D Printers from the Cloud:  A Step Toward 3D Printer Control as a Service

2018 ◽  
Author(s):  
Chinedum Okwudire ◽  
Sharankumar Huggi ◽  
Sagar Supe ◽  
Chengyang Huang ◽  
Bowen Zeng
Keyword(s):  
South Carolina ◽  
Stepper Motor ◽  
3D Printer ◽  
Level Control ◽  
Transmission Delays ◽  
Low Level ◽  
Motor Commands ◽  
Ann Arbor ◽  
Local Controller ◽  
High Level

Control as a Service (CaaS) is an emerging paradigm where low-level control of a device is moved from a local controller to the Cloud, and provided to the device as an on-demand service. Among its many benefits, CaaS gives the device access to advanced control algorithms which may not be executable on a local controller due to computational limitations. As a step toward 3D printer CaaS, this paper demonstrates the control of a 3D printer by streaming low-level stepper motor commands (as opposed to high-level G-codes) directly from the Cloud to the printer. The printer is located at the University of Michigan, Ann Arbor, while its stepper motor commands are calculated using an advanced motion control algorithm running on Google Cloud computers in South Carolina and Australia. The stepper motor commands are sent over the Internet using the user datagram protocol (UDP) and buffered to mitigate transmission delays; checks are included to ensure accuracy and completeness of the transmitted data. All but one part printed using the cloud-based controller in both locations were hitch free (i.e., no pauses due to excessive transmission delays). Moreover, using the cloud-based controller, the parts printed up to 54% faster than using a standard local controller, without loss of accuracy.

scholarly journals Bridging the Gap between High-Level Reasoning and Low-Level Control

2009 ◽  
pp. 342-354 ◽  
Author(s):  
Ozan Caldiran ◽  
Kadir Haspalamutgil ◽  
Abdullah Ok ◽  
Can Palaz ◽  
Esra Erdem ◽  
...  
Keyword(s):  
Level Control ◽  
Low Level ◽  
High Level

scholarly journals Development of a Low-Level Control System for the ROV Visor3

2016 ◽  
Vol 2016 ◽  
pp. 1-12 ◽  
Author(s):  
Santiago Rúa ◽  
Rafael E. Vásquez
Keyword(s):  
Mathematical Model ◽  
Control System ◽  
Nonlinear Observer ◽  
Navigation Systems ◽  
Level Control ◽  
Remotely Operated Vehicle ◽  
Low Level ◽  
Level Control System ◽  
High Level ◽  
And Control

This paper addresses the development of the simulation of the low-level control system for the underwater remotely operated vehicle Visor3. The 6-DOF mathematical model of Visor3 is presented using two coordinated systems: Earth-fixed and body-fixed frames. The navigation, guidance, and control (NGC) structure is divided into three layers: the high level or the mission planner; the mid-level or the path planner; and the low level formed by the navigation and control systems. The nonlinear model-based observer is developed using the extended Kalman filter (EKF) which uses the linearization of the model to estimate the current state. The behavior of the observer is verified through simulations using Simulink®. An experiment was conducted with a trajectory that describes changes in the x and y and yaw components. To accomplish this task, two algorithms are compared: a multiloop PID and PID with gravity compensation. These controllers and the nonlinear observer are tested using the 6-DOF mathematical model of Visor3. The control and navigation systems are a fundamental part of the low-level control system that will allow Visor3’s operators to take advantage of more advanced vehicle’s capabilities during inspection tasks of port facilities, hydroelectric dams, and oceanographic research.

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