Fig 4. Overview of the proof-of-concept wheelchair on the treadmill.

Top left: Control condition. The wheelchair was pulled forward by a rope attached to the rear handles in the original configuration. A linear force sensor measured the tension in the rope, and the direction of that force vector was determined by markers placed along the rope and handles. Top right: Test condition. The wheelchair was pulled forward by a rope attached to the push bar in the configuration, which includes a wheel with a cant angle of 0.1 radians. Bottom: Experimental setup. The wheelchair was pulled forward on a treadmill, carrying a 40 kg weight to simulate a human sitting in the device.