Steering system for heavy mobile medical equipment
In one embodiment of the invention, a steering system for mobile medical equipment is disclosed including left and right steerable wheel assemblies including left and right steerable wheels, left and right parallelogram linkages coupled to the left and right steerable wheel assemblies, a steering function generator coupled to the left and right parallelogram linkages, and a steering tiller coupled to the steering function generator. The left and right parallelogram linkages transfer differing left and right wheel angles to the left and right steerable wheel assemblies respectively. The steering function generator generates the left wheel angle (LWA) of the left steerable wheel and the right wheel angle (RWA) of the right steerable wheel. The steering tiller receives an input steering angle to generate the left wheel angle and the right wheel angle to control the direction of the mobile medical equipment around flooring.
1. A mobile medical equipment system comprising:
a mobile base to movably support medical equipment, the mobile base including
a chassis having a left side, a right side, a front side, and a back side;
at least one non-steerable wheel coupled to the chassis near the front side, the at least one non-steerable wheel to rotate to roll the mobile medical equipment system over a floor;
a first steerable wheel and a second steerable wheel spaced apart and pivotally coupled to the chassis near the back side, the first and second steerable wheels to steer the mobile medical equipment system around the floor; and
a steering system coupled to the chassis and the first and second steerable wheels, the steering system to receive directional input from a user and couple the directional input to the first and second steerable wheels, the steering system including
a pair of cam plates pivotally coupled to the chassis, the pair of cam plates having angled arms coupled to the first and second steerable wheels to respectively form a first wheel angle and a second wheel angle, the pair of cam plates further having a pair of cam follower slots,
a pair of short links pivotally coupled in parallel to the chassis, the pair of short links having a pair of cam followers inserted into the pair of cam follower slots to pivot the pair of cam plates,
a long link coupled between the pair of short links, the long link to pivot the pair of short links, and
a tiller link pivotally coupled to the chassis and the long link, the tiller link to laterally sweep the long link.
2. The mobile medical equipment system of claim 1 , wherein
the pair of cam follower slots are linear cam follower slots in the pair of cam plates.
3. The mobile medical equipment system of claim 2 , wherein
widths of the linear cam follower slots are larger than a diameter of the cam followers to reduce wear in the steering system.
4. The mobile medical equipment system of claim 1 , wherein
the medical equipment is a robotic patient-side surgery system including one or more robotic surgical arms.
5. The mobile medical equipment system of claim 1 , wherein
the steering system unequally converts the directional input from the user to the first and second steerable wheels such that a first wheel angle of the first steerable wheel does not equal a second wheel angle of the second steerable wheel unless the mobile medical equipment is to move straight.
6. The mobile medical equipment system of claim 1 , wherein
the steering system further includes
a tiller rotatably coupled to the chassis near the back side the tiller to receive the directional input from the user and pivot the tiller link.
7. The mobile medical equipment system of claim 6 , wherein
the steering system further includes; and
a first parallelogram linkage coupled between a first cam plate of the pair of cam plates and the first steerable wheel, and
a second parallelogram linkage coupled between a second cam plate of the pair of cam plates and the second steerable wheel.
8. The mobile medical equipment system of claim 7 , wherein
the first parallelogram linkage includes
a first caster link coupled to a caster of the first steerable wheel,
a first front steering link coupled between the first cam plate and the first caster link, and
a first rear steering link spaced apart from the first front steering link and coupled between the first cam plate and the first caster link, and
the second parallelogram linkage includes
a second caster link coupled to a caster of the second steerable wheel,
a second front steering link coupled between the second cam plate and the second caster link, and
a second rear steering link spaced apart from the second front steering link and coupled between the second cam plate and the second caster link.
9. The mobile medical equipment system of claim 1 , wherein
the at least one non-steerable wheel is a motorized wheel to drive the mobile medical equipment over the floor.
10. The mobile medical equipment system of claim 1 , wherein
the first wheel angle of the first steerable wheel and the second wheel angle of the second steerable wheel are limited to provide a radius turn with a radius of not less than half a width of the mobile base.
11. The mobile medical equipment system of claim 1 , wherein
the steering system limits the first wheel angle of the first steerable wheel and the second wheel angle of the second steerable wheel to avoid radius turns of substantially zero.
12. A mobile medical equipment system comprising:
a mobile base to movably support medical equipment, the mobile base including
a chassis having a left side, a right side, a front side, and a back side;
at least one non-steerable wheel coupled to the chassis near the front side, the at least one non-steerable wheel rotates to roll the mobile medical equipment system over a floor;
a first steerable wheel and a second steerable wheel spaced apart and pivotally coupled to the chassis near the back side, the first and second steerable wheels to steer the mobile medical equipment system around the floor; and
a steering system coupled to the chassis and the first and second steerable wheels, the steering system to receive directional input from a user, the steering system to couple the directional input to the first and second steerable wheels, the steering system including
a pair of angled arms having a pair of cam follower slots, a first angled arm of the pair of angled arms coupled to the first steerable wheel and a second angled arm of the pair of angled arms coupled to the second steerable wheel,
a pair of ground links spaced apart and pivotally coupled to the chassis, the pair of ground links having a pair of cam followers inserted into the pair of cam follower slots of the pair of angled arms,
a sliding bar pivotally coupled to the pair of ground links, and
a tiller link pivotally coupled to the sliding bar.
13. The mobile medical equipment system of claim 12 , wherein
the pair of cam follower slots are linear cam follower slots in which the respective cam followers linearly slide.
14. A mobile medical equipment system comprising:
a mobile base to movably support medical equipment, the mobile base including
a chassis having a left side, a right side, a front side, and a back side;
at least one non-steerable wheel coupled to the chassis near the front side, the at least one non-steerable wheel to rotate to roll the mobile medical equipment system over a floor;
a first steerable wheel and a second steerable wheel spaced apart and pivotally coupled to the chassis near the back side, the first and second steerable wheels to steer the mobile medical equipment system around the floor; and
a steering system coupled to the chassis and the first and second steerable wheels, the steering system including
a first cam plate pivotally coupled to the chassis, the first cam plate having a first cam follower slot and a first angled arm coupled to the first steerable wheel to pivot and form a first wheel angle;
a second cam plate spaced apart from the first cam plate and pivotally coupled to the chassis, the second cam plate having a second cam follower slot and a second angled arm coupled to the second steerable wheel to pivot and form a second wheel angle;
a first short link pivotally coupled to the chassis, the first short link having a first cam follower inserted into the first cam follower slot to pivot the first cam plate;
a second short link spaced apart from the first short link and pivotally coupled to the chassis, the second short link having a second cam follower inserted into the second cam follower slot to pivot the second cam plate;
a long link pivotally coupled to the first short link and the second short link, the long link to convert a lateral sweeping motion into parallel pivotal motions of the first short link and the second short link;
a tiller link pivotally coupled to the chassis and the long link, the tiller link to pivot to receive the directional input of the user and laterally sweep the long link.
15. The mobile medical equipment system of claim 14 , wherein the steering system further includes
a tiller pivotally coupled to the chassis, the tiller to receive the directional input from the user and pivot the tiller link.
16. The mobile medical equipment system of claim 14 , wherein the steering system further includes
a first parallelogram linkage coupled between the first cam plate and the first steerable wheel, and
a second parallelogram linkage coupled between the second cam plate and the second steerable wheel.
17. The mobile medical equipment system of claim 14 , wherein
the at least one non-steerable wheel is a motorized wheel to drive the mobile medical equipment over the floor.