Search

Many disabled people are not suitable for the control of the current mainstream manual joystick-controlled wheelchair, so the study of new control methods can provide convenience for these people, including bioelectrical signal control, voice control, and visual control, but these control methods have peripheral equipment complex or susceptible to environmental noise interference, in contrast. These problems can be solved effectively by using a wearable flexible sensor to recognize human movement signal. To collect and identify the strain signal characteristics of the moving neck muscles, based on the principle of flexible piezoresistive sensor, we designed and produced a K-carrageenan at polydimethylsiloxane (PDMS) flexible sensor, designed a series of experiments to explore the conductive properties, mechanical properties, and air permeability of the sensor, and also designed the peripheral acquisition circuit and signal processing algorithm. Finally, the empirical mode decomposition (EMD)-long short-term memory (LSTM) algorithm is used to classify the signal and explore the feasibility of fitting the signal to the human neck to control the wheelchair. The results show that the maximum tensile rate of the sensor designed by us is as high as 180%, and the air permeability is also improved slightly. After 1000 cycles of stretching, the sensor still has good performance and can effectively collect human neck action signals. Through the field test, the accuracy of this system is up to 95%, which provides a new idea for wheelchair control.

Owing to the advantages of safety and reproducibility, remote center of motion (RCM) mechanisms are widely adopted in lumbar puncture (LP) procedures to guide the insertion angle and depth of the end effector. However, the proximal-actuated pattern in existing RCM mechanisms occupies a large space near the end effector, which obstructs the visual field and increases the system inertia. In this work, a base-actuated three-rhombus configured RCM mechanism for LP operation is first proposed, where the symmetric three-rhombus scheme is designed for motion transmission. As a result, the rotational and translational motions of the needle are respectively realized through the homodromous and heterodromous actuation of the two base-mounted motors. Kinematic models are established to analyze the manipulability, singularity, and workspace of the RCM mechanism theoretically. The parameter optimization procedure is provided to minimize the footprint of the RCM mechanism. Experimental results show that the mechanism reaches an insertion angle from −29.2 deg to 29.2 deg, a maximum insertion depth of 60.02 mm, and a footprint of 4.98 × 104 mm2. The relative error of the RCM point is 1.1 mm.