A novel approach for human intention recognition based on hall effect sensors and permanent magnets

Human intention recognition is important for any interaction between the user and the exoskeleton. This study proposes a novel approach, based on a contactless sensory system, using linear Hall effect sensors to recognize human intentions. This contactless sensory system consists of four Hall effect sensors mounted on the exoskeleton, whilst a ring-shaped permanent magnet with diametrical magnetization consisting of two semi-rings is worn on the user’s forearm. The model of the magnetic field created by the permanent magnet is also developed. Based on the developed magnetic field model and by interpreting the signals from the Hall effect sensory system received while the user’s elbow and forearm move, the intention identification algorithm is derived. A lightweight elbow and forearm assistive exoskeleton is developed. The proposed approach for human intention recognition is used to assist in controlling the exoskeleton, following the wearer’s intended motions. By implementing this contactless sensory system, wearers can use the exoskeleton easily and can move their forearm comfortably, while the human intention motion is recognized and used to control the exoskeleton. Moreover, achieved signals are unaffected by skin perspiration and muscle fatigue. As the sensory system is mounted on the exoskeleton, there is only indirect contact between the user’s body and the sensors, leading to improved comfort. Finally, the system does not require expert knowledge to place the sensors on the body of the user. This approach can be extended to detect human intentions for the control of exoskeletons with more degrees of freedom.