Traditional bracing systems that include a spinal orthosis improve posture in persons with paraplegia during standing and walking, but also limit the wearer’s range of motion during other activities, such as vehicle transfer or sitting and reaching for objects. In order to regain full torso flexibility the user would need to remove the spinal orthosis, which can be arduous and time consuming. A Convertible Spinal Orthosis (CSO) that allows the user to switch between Locked rigid torso support and Unlocked free motion has been designed, fabricated and tested. Analysis of movement has been performed with an able-bodied and a paraplegic subject wearing a rigid spinal orthosis, the CSO in both the Locked and Unlocked states, and without any bracing, while performing the following movements: lateral bend, axial twist, forward flexion, and downward flexion. Statistical comparisons were made between maximum body segment angles in the Rigid & Locked, and Unlocked & No Brace configurations. While differences were typical in movement between the top and bottom portions of the brace, half of the movements at the upper torso or shoulder level were statistically indistinguishable (α = 0.05) across compared configurations.
Similarly, mobile robots can benefit from body flexibility, especially in maneuvering around obstacles or conforming to small spaces. Two compliant-bodied platforms are being explored. “Cheeter” is a proof of concept hopping robot, and “Caterpillar Whegs” is a wheel-legged robot with flexible connections between rigid segments. These connections are cable-controlled to implement turning and dorsal flexion. Cheeter moves forward at a rate of approximately 3.7 cm/s on carpet, or 5 cm/s on tile, and the flexible spine allows more than 90° of bending in all directions. The Caterpillar Whegs robot runs at a maximum speed of 35 cm/s on carpet and 37 cm/s on tile, can climb up to a 4 cm obstacle, and can turn smoothly with a radius of 52 cm. The size of the segments, the height of the wheel-legs, and the amount of controlled inter-segment bending define the space in which the robot can navigate. The mechanically simple bending mechanisms make Caterpillar Whegs particularly scalable, and the ability to simultaneously drive the wheels, flex, and turn could offer exciting possibilities for multi-modal locomotion.