There is increasing interest in shared control for assistive robotics with adaptable levels of supervised autonomy. In this work, we present a user-adaptive multi-layer shared control scheme for control of assistive devices. The system leverages the advantages of brain-inspired hyperdimensional computing (HDC) for classification & recall of reactive robotic behavior including high performance, computational efficiency and intelligent sensor fusion, to execute actuation based on the user's goal while alleviating the burden of fine control. Using a multi-modal dataset of activities of daily living, we first recognize the user's most recent behaviors, then predict the user's next action based on their habitual action sequences, and finally, determine actuation through HDC recall-based shared control which intelligently deliberates between the predicted action and sensor feedback-based autonomy. In this work, we independently implement each layer to achieve >92% accuracy and then integrate the layers and discuss the combined performance and methods to reduce accumulated error.

Hyperdimensional Computing (HDC) is a computationally efficient method of performing highly-accurate classification by encoding information into very wide binary vectors with simple binary operations. In this work, we explore methods of accelerating the encoding process, demonstrated on a RISC-V processor. First, we propose a bit-serial word-parallel approach to accelerate the spatial encoder, the slowest HDC block, and demonstrate its promise with a 12.6 x speedup over prior methods. Then, we describe methods to vectorize each HDC block. Implementation on a vector accelerator achieves a 12.2 x speedup and 7.1 x reduction in energy/prediction. Finally, we gain an additional 20% improvement in energy efficiency by finding the optimal balance between vector lanes and execution time, overall demonstrating the significant speed and energy improvements that a vector processor can provide for HDC.

Hyperdimensional computing (HDC) is a brain-inspired computing paradigm that operates on pseudo-random hypervectors, an information-rich, hardware-efficient representation that is robust to noise and facilitates learning with limited training data. This work explores how robot navigation tasks can leverage the high-capacity hypervector representation to enable behavioral prioritization through a weighted encoding of heterogeneous sensor information. Experiments over 100 trials in each of the 100 randomly generated obstacle maps demonstrate that the proposed weighted sensor encoding scheme boosts the success rate of the navigation task by over 30% compared to an unweighted sensor encoding. A hybrid scheme using the HDC weighted scheme at the input of a deep feed-forward neural network achieves the highest success rate. The hybrid scheme furthermore is more robust when reducing the HDC dimension by 50%. However, the simple HDC implementation remains the most hardware efficient, making it desirable for resource-constrained systems.

EMG-based gesture recognition shows promise for human-machine interaction. Systems are often afflicted by signal and electrode variability which degrades performance over time. We present an end-to-end system combating this variability using a large-area, high-density sensor array and a robust classification algorithm. EMG electrodes are fabricated on a flexible substrate and interfaced to a custom wireless device for 64-channel signal acquisition and streaming. We use brain-inspired high-dimensional (HD) computing for processing EMG features in one-shot learning. The HD algorithm is tolerant to noise and electrode misplacement and can quickly learn from few gestures without gradient descent or back-propagation. We achieve an average classification accuracy of 96.64% for five gestures, with only 7% degradation when training and testing across different days. Our system maintains this accuracy when trained with only three trials of gestures; it also demonstrates comparable accuracy with the state-of-the-art when trained with one trial.