Power sensing eddy current resistance unit for an exercise device

A method of controlling a resistance arrangement of an exercise system that includes an input area for applying user input power, wherein the exercise system includes a rotatable member that rotates in response to a user-applied input force at the input area, comprising the steps of:

• rotating the rotatable member about an axis of rotation in response to application of the user-applied input force to the input area, wherein the input area comprises a pedal arrangement, wherein rotation of the rotatable member in response to the application of input power to the pedal arrangement causes rotation of a conductive member;
• and
• resisting the rotation of the rotatable member through the use of eddy currents established by interaction of the conductive member and a magnet arrangement, wherein the magnet arrangement includes a magnet carrier having one or more magnets located adjacent the conductive member at a location radially offset from the axis of rotation;
• a nonrotatable beam having a supported inner end and an unsupported outer end, wherein the inner end of the beam is fixed and wherein the magnet carrier is secured to the beam at a location axially outwardly of the unsupported inner end of the beam, wherein the beam, the magnet carrier and the one or more strain sensing members are configured and arranged such that the magnet carrier is spaced outwardly from the one or more strain sensing members in an axial direction parallel to the axis of rotation, and wherein the beam, the magnet carrier and the one or more strain sensing members are spaced radially outwardly from the axis of rotation;
• and
• sensing strain in the beam using one or more strain sensing members when the rotatable member is rotated to establish eddy current resistance by the interaction between the magnets of the magnet carrier and the conductive member, wherein the beam, the magnet carrier and the one or more strain sensing members are configured and arranged such that the magnet carrier is spaced outwardly from the one or more strain sensing members in an axial direction parallel to the axis of rotation, and wherein the strain in the beam corresponds to the user input power.

An exercise system, comprising:

• a user input area that includes a pedal arrangement;
• a rotatable member that rotates about an axis of rotation in response to an input force applied by a user on the pedal arrangement;
• a conductive member that rotates in response to rotation of the rotatable member;
• and
• a resistance unit comprising a magnetic member positioned adjacent the conductive member at a location spaced radially outwardly of the axis of rotation, for providing eddy current resistance to rotation of the rotatable member in response to rotation of the conductive member;
• means for causing relative movement between the magnetic member and the conductive member for varying the eddy current resistance;
• and torque sensing means associated with the magnetic member, including a nonrotatable cantilever member defining an unsupported outer end with which the magnetic member is interconnected, and strain sensing means for sensing strain in the cantilever member, wherein the strain sensing means comprises one or more strain sensors interconnected with the cantilever member at a location radially outwardly of the axis of rotation and axially inwardly of the magnetic member.

A power sensing resistance arrangement for an exercise device that includes an input area for applying user input power, comprising:

• a rotatable member that rotates in response to the application of the user input power, wherein the rotatable member rotates about an axis of rotation;
• a conductive member associated with the rotatable member, wherein the conductive member is formed of an electrically conductive material and rotates in response to rotation of the rotatable member;
• and
• a magnet assembly which cooperates with the conductive member to establish eddy currents to resist rotation of the rotatable member, wherein the magnet assembly includes a magnet carrier having one or more magnets located adjacent the conductive member at a location radially offset from the axis of rotation;
• a nonrotatable beam having a supported inner end and an unsupported outer end, wherein the inner end of the beam is fixed and wherein the magnet carrier is secured to the beam at a location axially outwardly of the supported inner end of the beam;
• one or more strain sensing members interconnected with the beam between the magnet carrier and the supported inner end of the beam;
• a mounting member secured to the inner end of the beam, wherein the mounting member is configured to support the inner end of the beam, and wherein the one or more strain sensing members comprise one or more strain gauges secured to the beam outwardly of the mounting member;
• and means for causing relative movement between the magnet carrier and the conductive member for varying the magnitude of the eddy current forces caused by rotation of the conductive member relative to the magnet carrier, wherein the means for causing relative movement between the magnet carrier and the conductive member comprises a linear actuator interconnected with the mounting member, and wherein the linear actuator is operable to axially move the beam, and thereby the magnet carrier, toward and away from the conductive member, and wherein the beam, the magnet carrier and the one or more strain sensing members are configured and arranged such that the magnet carrier is spaced outwardly from the one or more strain sensing members in an axial direction parallel to the axis of rotation, and wherein the beam, the magnet carrier and the one or more strain sensing members are spaced radially outwardly from the axis of rotation, and wherein the one or more strain sensing members are configured and arranged to sense strain experienced by the beam when the rotatable member is rotated to establish eddy current resistance by the interaction between the magnets of the magnet carrier and the conductive member, wherein the strain in the beam corresponds to the user input power.