The present invention provides steerable devices, such as catheters, having length, a proximal end, and a distal end that includes at least one shape memory structure incorporated into the device and configured such that graded or stepped bending of the shape memory structure may be achieved by variably heating the shape memory structure along some or all of the length of the shape memory structure to one or more transformation temperatures associated with the shape memory material either gradually or in steps, and driving devices providing the drive signal and/or energy to heat the shape memory structure to enable graded or stepped control thereof.