Abstract: An actuator apparatus includes an actuator rod with a interior cavity and a set of rod holes extending through the actuator rod to the cavity. The apparatus includes a light assembly positioned to light the cavity and an actuator block with an opening sized to conform to an outer surface of the actuator rod and one or more block holes in the opening. Each of the block holes is positioned to align with each of the rod holes as the actuator rod moves with respect to the actuator block. The actuator block includes a light sensor positioned to sense light coming through a rod hole aligned with the block hole. The apparatus includes a verification module with a light modulator that modulates light of the light assembly to transmit a position signal, and a verification circuit that transmits a verification signal after the light sensor receives the position signal.

Abstract: An actuator apparatus includes an actuator rod with an interior cavity and a set of rod holes. Each rod hole extends through the actuator rod to the cavity. The set of rod holes is positioned in a straight line. The apparatus includes a light assembly that is positioned to light the cavity. The apparatus includes an actuator block that includes an opening extending through the actuator block sized to conform to an outer surface of the actuator rod and a set of block holes in the opening. Spacing between the block holes matches spacing between the rod holes. The actuator block includes a light sensor positioned in a block hole to sense light coming through a rod hole aligned with the block hole and a ball bearing for each block hole of the set of block holes without a light sensor and extending partially through the corresponding block hole.