Rowing exercise machines having a configurable rowing feel

1. A rowing exercise machine comprising:

a movable inertial element,

an eddy current brake coupled to the movable inertial element,

a rowing grip coupled to the movable inertial element, and

control circuitry coupled to the eddy current brake, the control circuitry configured to cause the eddy current brake to provide a resistance to motion of the rowing grip during part or all of a rowing stroke that conforms to a target resistance to motion of the rowing grip,

wherein the control circuitry is configured to adjust one or more parameters of a control model of the rowing exercise machine iteratively as part of a feedback loop in real-time during motion of the rowing grip, the feedback loop including an iterative adjustment of a current applied to the eddy current brake.

2. The rowing exercise machine of claim 1 in which the information contained in the storage is not changeable.

3. The rowing exercise machine of claim 1 in which the information contained in the storage is changeable to information received at the rowing exercise machine through the Internet.

4. The rowing exercise machine of claim 1 in which the information contained in the storage is changeable in response to inputs from user interface controls of a user interface.

5. The rowing exercise machine of claim 1 in which the target resistance to motion comprises a resistance to motion of an existing model or design of a mechanical ergometer.

6. The rowing exercise machine of claim 1 in which the target resistance to motion is the same as a target resistances to motion of another rowing exercise machine of a given model or design.

7. The rowing exercise machine of claim 1 in which the target resistance to motion applies to a series of successive strokes during a rowing session of a rower.

8. The rowing exercise machine of claim 1 in which the target resistance to motion is different for different strokes during a rowing session of a rower.

9. The rowing exercise machine of claim 1 in which the resistance to motion of the rowing grip caused by the control circuitry is based on one or more parameter values, and the parameter values comprise one or more of: position of the rowing grip, velocity of the rowing grip, ambient temperature, timing in relation to a training schedule, heart rate of a user, skin resistance of the user, and intervention by an observer.

10. The rowing exercise machine of claim 1 , wherein the one or more parameters of the control model of the rowing exercise machine comprises at least one of a torque gain, a current gain, or a speed gain.

11. The rowing exercise machine of claim 1 , wherein the control circuitry stores an approximation of a relationship between the current applied to the eddy current brake and a torque value, and

wherein the control circuitry is configured to determine the current applied to the eddy current brake based on a torque table.

12. The rowing exercise machine of claim 11 , wherein the approximation of the relationship comprises a torque table, and

wherein the control circuitry is configured to recompute the torque table during the motion of the rowing grip so as to decrease a difference between the resistance to motion of the rowing grip and the target resistance to motion of the rowing grip.

13. The rowing exercise machine of claim 1 , wherein the control circuitry is configured to, during a recovery phase of the rowing stroke, test a response of the eddy current brake to a test current that is different from a current associated with conforming the resistance to motion of the rowing grip to the target resistance to motion of the rowing grip.