Treadmill with vertically displaceable platform
A treadmill has a base with a vertically displaceable platform. A mechanism is provided that resists the downward movement of the platform in response to a load applied to the platform. The mechanism also rebounds the platform upwardly with a force applied to the platform in response to a decrease of a load on the platform. A support structure enables stable vertical positioning of the platform with respect to the base.
1. A treadmill, comprising:
a base;
a platform movably coupled to the base;
a drive roller rotatably coupled to the base;
a belt extending across the drive roller and the platform; and
a linear actuator coupled between the base and the platform, the linear actuator comprising a voice coil actuator, wherein the linear actuator is coupled to a piston.
2. The treadmill of claim 1 , wherein the linear actuator powers both extension and retraction of the piston.
3. The treadmill of claim 1 , wherein the piston is extendable and retractable along a direction approximately parallel to a length of the platform.
4. The treadmill of claim 3 , further comprising a bell crank pivotally coupled to the base at a pivot point, wherein the bell crank comprises:
a first end coupled to the piston, and
a second end coupled to the platform,
wherein the bell crank converts linear movement of the piston into a force applied approximately perpendicular to the platform.
5. The treadmill of claim 4 ,
wherein the first end of the bell crank is spaced a first distance from the pivot point and the second end of the bell crank is spaced a second distance from the pivot point, and
wherein the second distance is greater than the first distance so that a linear movement of the piston is amplified when applied to the platform.
6. The treadmill of claim 1 , further comprising a pair of idler rollers rotatably mounted on the treadmill.
7. The treadmill of claim 1 , wherein the linear actuator is coupled to a load cell transducer.
8. The treadmill of claim 1 , wherein the linear actuator comprises one of a plurality of linear actuators each coupled to a corresponding piston.
9. The treadmill of claim 8 , wherein the plurality of linear actuators comprise part of a resistance/rebound mechanism coupled to the base and to the platform, the resistance/rebound mechanism capable of providing selectively controlled displacement resistance in a first direction and selectively controlled rebound responsiveness in an opposite second direction.
10. A resistance/rebound mechanism for a treadmill, comprising:
a linear actuator comprising a voice coil actuator;
a transducer; and
a bell crank,
wherein the linear actuator is coupled to the bell crank, and
wherein extension or retraction of the linear actuator along a first direction translates into movement of the bell crank in a second direction that is approximately perpendicular to the first direction.
11. The resistance/rebound mechanism of claim 10 , wherein the bell crank comprises a pivot point and a linkage.
12. The resistance/rebound mechanism of claim 11 , wherein the linkage comprises a first end and a second end, wherein the first end is coupled to the bell crank at a pivot connection, and wherein the second end is coupled to a mounting bracket.
13. The resistance/rebound mechanism of claim 10 , wherein the bell crank comprises one of a plurality of bell cranks.
14. The resistance/rebound mechanism of claim 10 , wherein the resistance/rebound mechanism is capable of providing selectively controlled displacement resistance in a first direction and selectively controlled rebound responsiveness in an opposite second direction.
15. The resistance/rebound mechanism of claim 10 , further comprising a buffer spring coupled to the linear actuator.
16. The resistance/rebound mechanism of claim 10 , wherein the linear actuator is coupled to the bell crank at a pivot joint or a ball joint.
17. A system for a treadmill, comprising:
a plurality of resistance/rebound mechanisms each comprising:
a linear actuator that comprises a voice coil actuator;
a transducer, and
a bell crank;
wherein extension or retraction of the linear actuator along a first direction translates into movement of the bell crank in a second direction that is approximately perpendicular to the first direction.
18. The system of claim 17 , wherein the linear actuator is coupled to a piston, and wherein the linear actuator powers both extension and retraction of the piston.
19. The system of claim 17 , wherein the plurality of resistance/rebound mechanisms comprise at least four resistance/rebound mechanisms positioned on a surface of the treadmill.