Abstract: A mobile medical diagnostic device having a mobility chassis with two supporting wheels and a central steerable drive wheel. The device has an electrical power steering system controlled by two synchronized handles operable by wrist action of an operator walking behind the device. The handles include a rotatable grip for controlling the velocity of the device. Advancing the grip actuates the throttle to the drive wheel and retarding the grip actuates a proportional electromechanical braking system. The device includes a proximity detector system which uses ultrasonic transducers to determine when an obstacle is within close proximity to the device, and to responsively and automatically actuate the brake system. The device has a stabilization system which automatically extends an outboard support on each side of the central wheel when the device is positioned for diagnostic analysis and automatically retracts the supports to facilitate mobility of the device.