Rowing exercise machines having a configurable rowing feel
Among other things, a rowing exercise machine includes 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 to cause a resistance to motion of the rowing grip during part of a rowing stroke. The resistance to motion of the rowing grip during the drive phase of the rowing stroke conforms to a target feel for a rower. The target feel corresponds to a feel for a rower of a target other rowing exercise machine or other target feel of interest.
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 create a resistance to motion of the rowing grip during a series of rowing strokes,
wherein each rowing stroke comprises a drive phase and a recovery phase, and
wherein the control circuitry is configured to
during the drive phase, control the eddy current brake to conform the resistance to motion to a target resistance to motion,
during the recovery phase, apply a test current in the eddy current brake, wherein the test current is different from a current associated with the target resistance to motion, and
based on a response of the eddy current brake to the test current, adjust the control of the eddy current brake during the drive phase.
2. The rowing exercise machine of claim 1 , wherein a magnitude of the test current is in a range of magnitudes of currents applied to conform the resistance to motion to the target resistance to motion during the drive phase.
3. The rowing exercise machine of claim 1 , wherein the control circuitry is configured to:
determine a first difference between a measured rotational speed of the movable inertial element during the recovery phase and an expected rotational speed of the movable inertial element during the recovery phase, or a second difference between a measured derivative of a rotational speed of the movable inertial element during the recovery phase and an expected derivative of the rotational speed of the movable inertial element during the recovery phase; and
adjust the control of the eddy current brake based on the first difference or the second difference.
4. The rowing exercise machine of claim 1 , wherein applying the test current in the eddy current brake causes a rotational speed of the movable inertial element to deviate from a target rotational speed profile, and
wherein the control circuitry is configured to return the rotational speed of the movable inertial element to the target rotational speed profile prior to a next drive phase.
5. The rowing exercise machine of claim 1 , wherein adjusting the control of the eddy current brake comprises adjusting one or more parameters of a control model of the rowing exercise machine.
6. The rowing exercise machine of claim 5 , wherein the one or more parameters comprise one or more of a torque gain value, a current gain value, or a speed gain value.
7. The rowing exercise machine of claim 1 , wherein adjusting the control of the eddy current brake comprises re-computing a mapping between currents and corresponding resistances to motion.
8. 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 create a resistance to motion of the rowing grip during a series of rowing strokes by a rower,
determine a difference between an expected energy delivered by the rower over a full rowing stroke and a measured energy delivered by the rower over the full rowing stroke, and
based on the difference, adjust control of the eddy current brake, wherein the control of the eddy current brake causes the resistance to motion to conform to a target resistance to motion.
9. The rowing exercise machine of claim 8 , wherein determining the difference comprises summing values over a plurality of instruction cycles of the full rowing stroke, wherein the values are based on measured rotational speeds of the movable inertial element.
10. The rowing exercise machine of claim 8 , wherein adjusting the control of the eddy current brake comprises adjusting one or more parameters of a control model of the rowing exercise machine.
11. The rowing exercise machine of claim 10 , wherein the one or more parameters comprise one or more of a torque gain value, a current gain value, or a speed gain value.
12. The rowing exercise machine of claim 8 , wherein adjusting the control of the eddy current brake comprises re-computing a mapping between currents and corresponding resistances to motion.
13. 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:
apply a control current component in the eddy current brake to cause a resistance to motion by the eddy current brake to conform to a target resistance to motion during a series of rowing strokes,
inject a second current component into the eddy current brake, wherein the second current component is distinct from the control current component and is configured to cause a resistance to motion that is imperceptible by users of the rowing exercise machine, and
based on a response of the eddy current brake to the second current component, adjust the control current component.
14. The rowing exercise machine of claim 13 , wherein the resistance to motion caused by the second current component has a frequency above human perception.
15. The rowing exercise machine of claim 14 , wherein the second current component is a zero-mean signal.
16. The rowing exercise machine of claim 13 , wherein the resistance to motion caused by the second current component has a magnitude below human perception.
17. The rowing exercise machine of claim 16 , wherein the control circuitry is configured to:
measure the response of the eddy current brake to the second current component over multiple strokes; and
adjust the control current component based on the response over the multiple strokes.
18. The rowing exercise machine of claim 13 , wherein adjusting the control current component comprises adjusting one or more parameters of a control model of the rowing exercise machine.
19. The rowing exercise machine of claim 18 , wherein the one or more parameters comprise one or more of a torque gain value, a current gain value, or a speed gain value.
20. The rowing exercise machine of claim 13 , wherein adjusting the control current component comprises re-computing a mapping between currents and corresponding resistances to motion.