Motion Modeling and Control of Lower Limb Exoskeleton Based on Max-Plus Algebra

Max-plus algebra is a special method to describe the discrete event system. In this paper, it is introduced to describe the motion of lower limb exoskeleton. Based on the max-plus algebra and the timed event graph, the walking process of exoskeleton is modelled. The max-plus algebra approach can describe the logical sequence and safety condition in the walking process, which cannot be achieved via other conventional modelling approaches. The autonomous control of lower limb exoskeleton system is studied via the model based on max-plus algebra. In the end, an FSM (finite state machine) controller embedded with the max-plus algebra model is proposed, and the experiments show ideal speed and gait/phase period control effect, as well as the good safety and stable performance.

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A NOVEL CABLE-PULLEY UNDERACTUATED LOWER LIMB EXOSKELETON FOR HUMAN LOAD-CARRYING WALKING

Journal of Mechanics in Medicine and Biology ◽

10.1142/s0219519417400425 ◽

2017 ◽

Vol 17 (07) ◽

pp. 1740042

Author(s):

YANG LIU ◽

YONGSHENG GAO ◽

YANHE ZHU

Keyword(s):

Lower Limb ◽

Evaluation Method ◽

Joint Angle ◽

Metabolic Cost ◽

Human Motion ◽

Control Effect ◽

Effective Power ◽

Lower Limb Exoskeleton ◽

Load Carrying ◽

Power Assistance

Wearable lower limb exoskeleton has comprehensive applications such as load-carrying augmentation, walking assistance, and rehabilitation training by using many active actuators in the joints to reduce the metabolic cost generally. The traditional fully actuated exoskeleton is bulky and requires large energy consumption, and the passive exoskeleton is difficult to provide effective power assistance. To achieve both small number of actuators and good assisting performance, this paper proposes a cable-pulley underactuated principle-based lower limb exoskeleton. The exoskeleton dynamics was modeled and the human-exoskeleton hybrid model was analyzed via ADAMS and LifeMOD to provide an evaluation method for power assistance. By exploiting the control strategy and utilizing the synergies of torque and power assistance, the hip joint and the knee joint can be actuated by a single cable simultaneously. Moreover, the human-exoskeleton co-simulation method was utilized to verify the assisting performance and control effect. In this simulation, the upper toque peak and power required by human are obviously reduced by power assistance and the joint angle curves without exoskeleton are in accordance with the joint angle curves with exoskeleton almost. In conclusion, the designed exoskeleton is compatible with human motion and feasible to provide effective power assistance in load-carrying walking.

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Modeling and Finite-Time Sliding Model Control of a Lower Limb Exoskeleton for Use in Rehabilitation

10.21203/rs.3.rs-693630/v1 ◽

2021 ◽

Author(s):

Uddesh Kishor Tople ◽

Amrapali Anandkumar Khandare ◽

Atharv Dipak Itankar ◽

Satya Kartheek Dogga

Keyword(s):

Dynamic Model ◽

Lower Limb ◽

Finite Time ◽

Sliding Mode ◽

Dynamic Modelling ◽

Work Load ◽

Modeling And Control ◽

Lower Limb Exoskeleton ◽

Exoskeleton Robot ◽

Model Control

Abstract Exoskeleton systems in recent years has become a prime choice technology due to the various possibilities it can deliver. These possibilities comprise the assisting and rehabilitative techniques designed for disabled and elderly people, so that they can regain control of their limbs and in addition to this also to augment and boost the abilities of able-bodied persons during heavy work-load conditions. Many works are reported on the modeling and control of a exoskeleton robot, but very few paper discuss the complete derivation of the model of the system. Here, first the dynamic model of a physical system used as lower limb exoskeleton robot is obtained. Secondly the analysis of the system done that is derived through dynamic modelling of a 3-link robotic manipulator using Euler-Lagrange approach and validation of the corresponding model in simulation. Further, design of a finite-time SMC for desired trajectory tracking of the system is implemented. The dynamic model of the 3-link system and its control using finite-time sliding mode control are validated in MATLAB simulation environment.

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Modeling and control of a lower limb exoskeleton with two degrees of freedom

2012 9th International Conference on Electrical Engineering, Computing Science and Automatic Control (CCE) ◽

10.1109/iceee.2012.6421205 ◽

2012 ◽

Cited By ~ 2

Author(s):

R. Lopez ◽

S. Salazar ◽

J. Torres ◽

R. Lozano

Keyword(s):

Lower Limb ◽

Degrees Of Freedom ◽

Two Degrees Of Freedom ◽

Modeling And Control ◽

Lower Limb Exoskeleton ◽

And Control

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Modeling and control of discrete event systems using finite state machines with variables and their applications in power grids

Systems & Control Letters ◽

10.1016/j.sysconle.2011.10.010 ◽

2012 ◽

Vol 61 (1) ◽

pp. 212-222 ◽

Cited By ~ 16

Author(s):

Junhui Zhao ◽

Yi-Liang Chen ◽

Zhong Chen ◽

Feng Lin ◽

Caisheng Wang ◽

...

Keyword(s):

Discrete Event Systems ◽

Discrete Event ◽

Finite State Machines ◽

Power Grids ◽

State Machines ◽

Modeling And Control ◽

Event Systems ◽

Finite State ◽

And Control

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DEVELOPMENT OF A COMPACT LOWER-LIMB EXOSKELETON FOR WALKING ASSISTANCE: A CASE STUDY

Journal of Mechanics in Medicine and Biology ◽

10.1142/s0219519419400396 ◽

2019 ◽

Vol 19 (07) ◽

pp. 1940039

Author(s):

TIANJIAO ZHENG ◽

GANGFENG LIU ◽

TIANSHUO WANG ◽

YU ZHANG ◽

JIE ZHAO ◽

...

Keyword(s):

Lower Limb ◽

Control Method ◽

Effective Means ◽

Steel Cable ◽

Gait Generation ◽

Lower Limb Exoskeleton ◽

Fitting Method ◽

Finite State ◽

Reference Trajectories

Lower-limb exoskeletons are an effective means to provide paraplegic and hemiplegic individuals with the ability to walk upright. A lot of studies about lower-limb exoskeletons have been developed to assist the impaired populations. However, the existing devices are still too technically complex and expensive for practicality. In this paper, a compact lower-limb exoskeleton for walking assistance is developed, in which a steel-cable actuator is specially designed. In order to accomplish the different tasks presented to gait generation, a control method with multiple stages is employed. In this approach, four basic states and seven intended motions are designed for the finite-state machine. In addition, the reference trajectories of these intended motions are presented and fitted by a modified first-order polynomial-fitting method. Preliminary motion tests of the exoskeleton with three healthy subjects are performed. The results verify the effectiveness of the system design and the gait-generation approach proposed in this paper. The overall exoskeleton system is compact and the corresponding operations are convenient and reliable.

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