Enabling closed-loop control of the Modular Prosthetic Limb through haptic feedback

This article presents an overview of the sensory feedback systems integrated with the Modular Prosthetic Limb that enable closed-loop control. Sensors within each fingertip detect force applied to the fingertip along three axes, heat flux, contact at four locations, and vibration in three axes at a maximum rate of 400 Hz. The system processes data from the sensors in the prosthetic hand and effectuates the feedback either via haptic tactors, which convey force, vibration, or temperature, or alternatively through electrical stimulation via brain implants. Tactor systems are physically mounted at the interface between the user and the prosthetic device, within the socket. Research into direct cortical control and feedback is ongoing, and the system is designed with algorithms that transform the sensor data into a series of electrical stimulation pulses that can be perceived naturally by the brain. Enabling haptic feedback for closed-loop control has the potential to enable dexterous control with a prosthetic device. This article describes the need for sensory feedback systems in prosthetic limbs, the system design components (including the native human sensory system, prosthetic sensors, and actuators) for providing feedback, and the software algorithms used to control the system.