Exoskeleton robot control for synchronous walking assistance in repetitive manual handling works based on dual unscented Kalman filter

Abstract

Prolong walking is a notable risk factor for work-related lower-limb disorders (WRLLD) in industries such as agriculture, construction, service profession, healthcare and retail works. It is one of the common causes of lower limb fatigue or muscular exhaustion leading to poor balance and fall. Exoskeleton technology is seen as a modern strategy to assist worker’s in these professions to minimize or eliminate the risk of WRLLDs. Exoskeleton has potentials to benefit workers in prolong walking (amongst others) by augmenting their strength, increasing their endurance, and minimizing high muscular activation, resulting in overall work efficiency and productivity. Controlling exoskeleton to achieve this purpose for able-bodied personnel without impeding their natural movement is, however, challenging. In this study, we propose a control strategy that integrates a Dual Unscented Kalman Filter (DUKF) for trajectory generation/prediction of the spatio-temporal features of human walking (i.e. joint position, and velocity, and acceleration) and an impedance cum supervisory controller to enable the exoskeleton to follow this trajectory to synchronize with the human walking. Experiment is conducted with four subjects carrying a load and walking at their normal speed- a typical scenario in industries. EMG signals taken at two muscles: Right Vastus Intermedius (on the thigh) and Right Gastrocnemius (on the calf) indicated reduction in muscular activation during the experiment. The results also show the ability of the control system to predict spatio-temporal features of the pilots’ walking and to enable the exoskeleton to move in concert with the pilot.

The experimental investigation of the sensitivity in the exoskeleton control loop

“…Changes in the amplitude of the graphs obtained in this experiment indicate the presence of noise that needs to be filtered. Therefore, the next group of experiments was devoted to configuring the noise filter [17] for the parameter entering the control system. For this experiment, the moving average algorithm was selected.…”

Analisis Sistem Kendali Sendi Exoskeleton Robotik untuk Pola Pergerakan Manusia Normal

“…Exoskeleton ini berbentuk prototype ringan yang dapat dikendalikan menggunakan motor listrik serta sensor dari pergerakan otot manusia [1]. Terdapat penelitian tentang exoskeleton mulai dari struktur dan analisis exoskeleton melalui pemodelan sampai dengan pengontrolan manual pada sistem sendi exoskeleton [2]. Selain dari itu, beberapa penelitian yang telah dilakukan diperoleh suatu informasi bahwa exoskeleton berupa prototipe memiliki manfaat bagi manusia sehingga tentu diperlukan suatu penelitian lanjut mengenai gerak berjalan pada manusia [3].…”

Synthesis of exoskeleton control algorithms based on kinematic analysis of locomotions and human gait modelling

“…Therefore, to make up a working design model it is necessary to introduce a series of assumptions and changes. Taking into ac-count the previous experience of the scientists working in the fi eld of biomechanics [3][4][5][6][7][9][10][11][12], theoretical mechanics and the theory of mechanisms and machines, as well as drawing on the technical project to design and develop the high-tech production of a multifunctional ro-botic exoskeleton for medical purposes, we can accept the following kinematic scheme of a human walking mechanism (see Figure 3). While drawing a mathematical model, we introduced the following assumptions and simplifi cations:…”

“…The obtained dependences of the angular values can be input into the microcontroller which controls the electric rotary drives in pelvic and knee joints. For different locomotions, according to the models, we can calculate functional dependences, including those for transient motions [4,5,[7][8][9][10].…”

“…When designing the control system it is necessary to know the laws of motion [4] to eliminate extra and unnecessary movements. The response time of exoskeleton elements is also essential [5]. Asynchronous behaviour can cause serious health problems.…”