A lower limb exoskeleton control system based on steady state visual evoked potentials

作者：Kwak No Sang; Mueller Klaus Robert; Lee Seong Whan^*

来源：Journal of Neural Engineering, 2015, 12(5): 056009.

DOI：10.1088/1741-2560/12/5/056009

• brain-machine interface
• electroencephalogram
• steady state visual evoked potentials
• exoskeleton control

Objective. We have developed an asynchronous brain-machine interface (BMI)-based lower limb exoskeleton control system based on steady-state visual evoked potentials (SSVEPs). Approach. By decoding electroencephalography signals in real-time, users are able to walk forward, turn right, turn left, sit, and stand while wearing the exoskeleton. SSVEP stimulation is implemented with a visual stimulation unit, consisting of five light emitting diodes fixed to the exoskeleton. A canonical correlation analysis (CCA) method for the extraction of frequency information associated with the SSVEP was used in combination with k-nearest neighbors. Main results. Overall, 11 healthy subjects participated in the experiment to evaluate performance. To achieve the best classification, CCA was first calibrated in an offline experiment. In the subsequent online experiment, our results exhibit accuracies of 91.3 +/- 5.73%, a response time of 3.28 +/- 1.82 s, an information transfer rate of 32.9 +/- 9.13 bits/min, and a completion time of 1100 +/- 154.92 s for the experimental parcour studied. Significance. The ability to achieve such high quality BMI control indicates that an SSVEP-based lower limb exoskeleton for gait assistance is becoming feasible.

• 出版日期2015-10