  This paper presents an insole FSR (Force Sensing Resistor) to dynamically
detect weight variations in an exoskeleton system. The proposed methodology is
intended for tasks of lifting and lowering heavy weights with an industrial
exoskeleton to substantially reduce spinal loads during these manual handling
activities. Instead of extensively placing high-dense force sensors by covering
the whole plantar area, as most of commercial applications do, we integrate
only a few force sensors in specific plantar area, so that the sensory system
is not restricted to an individual foot size and shape, and on the other hand
has relatively lower material cost. Industrial exoskeletons are intended to
assist workers when handling heavy goods. With this in mind, wearers are not
able to use their hands to control the exoskeleton since they use them to
handle the goods. Therefore, the exoskeleton controller is required to
indirectly infer how much and when the wearer requires assistance for lifting
or lowering a heavy weight. Our approach of dynamically detect and characterize
the increment/decrement of weight, as well as the rising/falling edge, enables
the exoskeleton's controller to trigger the request of assistive force to the
actuators.
