Vertically Adjustable Automatic Step Stool

Abstract

A step stool includes an inner frame, an outer frame, an actuator, and a coupler. The inner frame includes two inner pillars, and the outer frame includes two outer pillars attached to a platform near opposite ends of the platform and configured to receive the two inner pillars. The actuator is coupled to one of the two inner pillars and one of the two outer pillars, and is operable to raise the outer frame relative to the inner frame. The coupler couples the two outer pillars to each other to evenly lift the opposite ends of the platform when the actuator raises the outer frame.

Description

FIELD

The present disclosure relates to step stools, and more particularly, to automatic step stools that are vertically adjustable.

BACKGROUND

This section provides background information related to the present disclosure which is not necessarily prior art.

Traditional step stools include collapsible steps that allow a user to elevate the user's body from the floor by climbing the steps. However, the user may be unable to climb steps due to a physical disability. Step stools or platforms have been developed that adjust automatically using a scissors-type linkage. However, these step stools are not suitable for home or hospital use and/or cause significant wear on the actuators used to adjust these step stools.

SUMMARY

This section provides a general summary of the disclosure, and is not a comprehensive disclosure of its full scope or all of its features.

A step stool includes an inner frame, an outer frame, an actuator, and a coupler. The inner frame includes two inner pillars, and the outer frame includes two outer pillars attached to a platform near opposite ends of the platform and configured to receive the two inner pillars. The actuator is coupled to one of the two inner pillars and one of the two outer pillars, and is operable to raise the outer frame relative to the inner frame. The coupler couples the two outer pillars to each other to evenly lift the opposite ends of the platform when the actuator raises the outer frame.

Further areas of applicability will become apparent from the description provided herein. The description and specific examples in this summary are intended for purposes of illustration only and are not intended to limit the scope of the present disclosure.

DRAWINGS

The drawings described herein are for illustrative purposes only of selected embodiments and not all possible implementations, and are not intended to limit the scope of the present disclosure.

FIG. 1 is a isometric view of a step stool according to the principles of the present disclosure, with the step stool in a lowered position;

FIG. 2A is a first isometric view of the step stool of FIG. 1, with the step stool in a raised position;

FIG. 2B is a close-up view of a portion of FIG. 2A within the line 2B;

FIG. 3 is a second isometric view of the step stool of FIG. 1, with the step stool in the raised position;

FIG. 4 is a top view of the step stool of FIG. 1;

FIG. 5 is a front view of the step stool of FIG. 1;

FIG. 6 is a side view of the step stool of FIG. 1;

FIG. 7 is a section view of the step stool of FIG. 1 taken along the line 7-7 shown in FIG. 5;

FIG. 8A is a section view of the step stool of FIG. 1 taken along the line 8-8 shown in FIG. 5;

FIG. 8B is a close-up view of a portion of FIG. 8A within the line 8B;

FIG. 9 is a partial section view of the step stool of FIG. 1 taken along the line 9-9 shown in FIG. 5;

FIG. 10A is a section view of the step stool of FIG. 1 taken along the line of FIG. 10-10 shown in FIG. 4;

FIG. 10B is a close up view of a portion of FIG. 10A within the line 10B;

FIG. 11 is a section view of the step stool of FIG. 1 taken along the line 11-11 shown in FIG. 5;

FIG. 12 is an isometric view of a first alternate embodiment of a step stool according to the principles of the present disclosure;

FIG. 13 is an isometric view of a second alternate embodiment of a step stool according to the principles of the present disclosure; and

FIG. 14 is a section view of the step stool of FIG. 13 taken along the line 14-14 shown in FIG. 13.

Corresponding reference numerals indicate corresponding parts throughout the several views of the drawings.

DETAILED DESCRIPTION

Example embodiments will now be described more fully with reference to the accompanying drawings. For purposes of clarity, the same reference numbers will be used in the drawings to identify similar elements.

Spatially relative terms, such as “left,” right,” “inner,” “outer,” “beneath,” “below,” “lower,” “above,” “upper,” and the like, may be used herein for ease of description to describe one element or feature's relationship to another element(s) or feature(s) as illustrated in the figures. Spatially relative terms may be intended to encompass different orientations of the device in use or operation in addition to the orientation depicted in the figures. For example, if the device in the figures is turned over, elements described as “below” or “beneath” other elements or features would then be oriented “above” the other elements or features. Thus, the example term “below” can encompass both an orientation of above and below. The device may be otherwise oriented (rotated 90 degrees or at other orientations) and the spatially relative descriptors used herein interpreted accordingly.

As used herein, the term module may refer to, be part of, or include an Application Specific Integrated Circuit (ASIC); an electronic circuit; a combinational logic circuit; a field programmable gate array (FPGA); a processor (shared, dedicated, or group) that executes code; other suitable components that provide the described functionality; or a combination of some or all of the above, such as in a system-on-chip. The term module may include memory (shared, dedicated, or group) that stores code executed by the processor.

The term code, as used above, may include software, firmware, and/or microcode, and may refer to programs, routines, functions, classes, and/or objects. The term shared, as used above, means that some or all code from multiple modules may be executed using a single (shared) processor. In addition, some or all code from multiple modules may be stored by a single (shared) memory. The term group, as used above, means that some or all code from a single module may be executed using a group of processors. In addition, some or all code from a single module may be stored using a group of memories.

Referring now to FIGS. 1 through 6, a step stool 10 according to the principles of the present disclosure will now be described. The step stool 10 can be adjusted automatically in the vertical direction. Thus, the step stool 10 is suitable for home use, hospital use, industrial use, and other types of uses.

The step stool 10 includes a lower or inner frame 12 and an upper or outer frame 14. The outer frame 14 is configured to receive the inner frame 12 so that the outer frame 14 can be placed over the inner frame 12. A sliding mechanism 16 guides the outer frame 14 relative to the inner frame 12. The sliding mechanism 16 allows the outer frame 14 to slide relative to the inner frame 12 with relatively low friction resistance. The slide mechanism 16 can be positioned on the forward and rearward faces of the pillars 26, 28, as shown, or at another suitable location.

An actuator 18 is coupled to the inner frame 12 and the outer frame 14. The actuator 18 is operable to raise and lower the outer frame 14 relative to the inner frame 12. The actuator 18 depicted includes a solenoid motor that receives power via a power cord 19. Alternatively, the actuator 18 can receive power from batteries, which can be rechargeable, and the power cord 19 can be omitted. Although the actuator 18 is depicted as including a solenoid motor, the actuator 18 can be electric, pneumatic, and/or hydraulic.

A coupler 20, such as a chain and sprocket mechanism, couples opposite lateral ends of the outer frame 14 to ensure that opposite lateral ends of the outer frame 14 are raised and lowered evenly. The actuator 18 is fixed to the left side of the inner frame 12 and the left side of the outer frame 14. Thus, as the actuator 18 extends, the actuator 18 exerts an upward force on the left side of the outer frame 14 to move the left side of the outer frame 14 is moved upward. As the left side of the outer frame 14 is moved upward, an upward force is exerted on the left side of the coupler 20. The coupler 20 transmits this upward force to the right side of the outer frame 14 such that equal upward forces are exerted on opposite lateral ends of the outer frame 14.

A control module 22 housed in a control box 23 communicates with a user interface 24 via a wire 25. The control box 23 includes an upper box 23a and a lower box 23b. The control module 22 controls the actuator 18 based on input received from a user via the user interface 24. Although the control box 23 is shown mounted to the left side of the inner frame, the control box 23 can be mounted to another suitable location such as to the center of the inner frame 12 underneath the outer frame 14. Similarly, although the user interface 24 is shown as a remote control connected via the wire 25, the user interface 24 can be integrated into the outer frame 14, or into a handle fixed to the outer frame 14, and the wire 25 can be omitted.

The user interface 24 includes one or more buttons and/or a touch screen that allow a user to command the step stool to raise and lower. The control module 22 can include relays, switches, and/or a power supply. The relays can open and close based on whether the user commands the step stool to raise or lower. The switches can be limit switches that stop the actuator 18 from extending or retracting when a travel limit has been met. The travel limit can be preset by the manufacturer of the step stool and/or adjusted by the user. For example only, the travel limit can be preset to approximately 25 inches. The power supply can convert power provided by the power cord 19 into power required by the actuator 18.

The inner frame 12 includes a right column or pillar 26, a left column or pillar 28, a cross-beam 30, wheel brackets 32, and brake brackets 34. The cross-beam 30 connects the right pillar 26 to the left pillar 28. The inner frame 12 can be made of metal, such as steel or aluminum, or plastic, such as polyurethane. Wheels 36, such as castor wheels, are attached to the wheel brackets 32. The wheels 36 enable a user to roll the step stool 10 to a desired position.

The step stool 10 can include one or more motors that drive the wheels 36, and the user may control motion of the wheels 36 via the user interface 24. In one example, a motor can be coupled to each of the wheels 36 to independently drive the wheels 36. In another example, a single motor, such as the motor included in the actuator 18, can be used in conjunction with a spider gear system to independently drive the wheels 36. Independently driving the wheels 36 allows the user to automatically move the step stool 10 forward, rearward, and in a turning direction.

Object sensors 38, such as infrared sensors, can be mounted to the wheel brackets 32 or to another suitable location. The object sensors 38 detects objects underneath the outer frame 14 and inform the control module 22 when objects are detected. The control module 22 prevents the actuator 18 from lowering the outer frame 14 when objects are detected.

Stabilizer feet or brakes 40 are mounted to the under side of the brake brackets 34. The brakes 40 can be manually adjusted by the user to engage the floor and thereby prevent the step stool 10 from rolling on the wheels 36. Although the brakes 40 are depicted as manually adjustable, the brakes 40 can be automatically adjusted via the control module 22, the user interface 24, and an actuator that actuates the brakes 40. In addition, although the brakes 40 are depicted as engaging the floor, the brakes 40 can engage the wheels 36 to prevent wheels 36 from rolling and thereby prevent the step stool 10 from rolling.

The outer frame 14 includes a platform 42 having a forward ramped end 43. The outer frame 14 also includes a left column or pillar 44 and a right column or pillar 46 positioned near opposite lateral ends of the platform 42. The outer frame 14 further includes a right handle 48 and a left handle 50 mounted on top of the right pillar 44 and the left pillar 46, respectively. The platform 42 can be corrugated to prevent a user from slipping. The ramped end 43 provides a gradual transition from the floor to the top surface of the platform 42 to assist the user in stepping or rolling a wheelchair onto the platform 42. The platform 42, the pillars 44, 46, and the handles 48, 50 can be made of metal, such as steel or aluminum, or plastic, such as polyurethane.

The pillars 44, 46 and the handles 48, 50 serve as safety rails or guiderails that prevent the user from falling down and/or from falling off of the platform 42. As shown, the handles 48, 50 are generally tubular and form oval rings that the user can grab onto. However, the handles 48, 50 can have various shapes, sizes, and textures that enable the user to grip the handles 48, 50.

With specific reference to FIG. 2B, the sliding mechanism 16 includes an outer bracket 52 fixed to the inner frame 12, an inner bracket 54 fixed to the outer frame 14. The sliding mechanism 15 also includes fasteners 56 fixing the outer bracket 52 and the inner bracket 54 to the inner frame 12 and the outer frame 14, and bearings 58, such as bearing balls, positioned between the outer bracket 52 and the inner bracket 54. The outer bracket 52 can nestingly receive the inner bracket 54 and the bearings 58 can be captured between the outer bracket 52 and the inner bracket 54. The bearings 58 reduce friction between the inner frame 12 and the outer frame 14 as the actuator 18 moves the outer frame 14 relative to the inner frame 12. In turn, wear on the actuator 18 is minimized, thereby extending the life of the actuator 18.

Referring now to FIG. 7, the coupler 20 includes one or more chains 60, lower sprockets 62, and upper sprockets 64. The chains 60 are routed around the perimeter of the sprockets 62, 64 and mesh with teeth of the sprockets 62, 64. As discussed in more detail below, the sprockets 62, 64 change the direction of an upward force exerted on one end of the chains 60 so that other end the chains 60 exert an upward force on the outer frame 14.

The outer frame 14 includes lower brackets 66 to which the platform 42 is mounted. The platform 42 can be attached to the brackets 66 via fasteners 68, or by an alternative attachment method such as welding. The outer frame 14 also includes brackets 70 to which a cover plate 72 is attached. The cover plate 72 can be attached to the brackets 70 via fasteners 74, or by an alternative attachment method such as welding. Although only the right side of the step stool 10 is shown, the platform 42 and the handle 50 can be attached to the outer frame 14 in a similar manner on the left side of the step stool 10.

Referring now to FIG. 8A, the actuator 18 includes a solenoid motor 76, a gear box 78, a cylinder 80, and a piston 82. The motor 76 rotates gears in the gear box 78 to extend and retract the piston 82 within the cylinder 80. The inner frame 12 includes a bracket 84 to which the bottom of the actuator 18 is mounted. A fastener 86, such as a pin, is used to fasten the bottom of the actuator 18 to the bracket 84 of the inner frame 12. The outer frame 14 includes a bracket 86 to which the top of the actuator 18 is mounted. A fastener 88, such as a pin, is used to fasten the top of the actuator 18 to the bracket 86 of the outer frame 14.

Referring now to FIG. 8B, the wheels 36 can be mounted to the wheel brackets 32 using swivel brackets 88. Fasteners 90 can be used to attach the swivel brackets 88 to the wheel brackets 32. Alternatively, the swivel brackets 88 can be welded to the wheel brackets 32. The swivel brackets 88 allow the wheels 36 to rotate about a vertical axis, which enables a user to rotate the step stool 10 about a vertical axis. In turn, the maneuverability of the step stool 10 is improved. The swivel brackets 88 offset the axes of the wheels 36 from the vertical axis about which the wheels rotate. Thus, the wheels 36 are mounted at a caster angle, which stabilizes movement of the wheels 36 and reduces loading on the swivel brackets 88. The swivel brackets are mounted to the wheel brackets 32 using fasteners 90.

Referring now to FIG. 9, fasteners 92, such as pins or screws, can be used to attach the wheels 36 to the swivel brackets 88. The wheels 36 rotate about the fasteners 92. In this regard, the fasteners 92 act as axels about which the wheels 36 rotate.

Near the center of the step stool 10, a retaining clip 94 can be used to retain the pin 86 within the bracket 84 of the inner frame 12. As discussed above, the bottom of the actuator 18 can be attached to the inner frame 12 using the bracket 84 and the pin 86. The retaining clip 94 can be easily removed from the pin 86 when repairing or replacing the actuator 18.

Referring now to FIG. 10A with continued reference to FIG. 9, the chains 60 of the coupler 20 include a first end 96 attached to the outer frame 14 via a chain bar 98. The chain bar 98 can be attached to the outer frame 14 using fasteners 100. Alternatively, the chain bar 98 can be welded to the outer frame 14. The chain bar 98 traps or clamps the first end 96 of the chains 60 to fix the first end 96 of the chains 60 to the outer frame 14.

The chains 60 also include a second end 102 fixed to the outer frame 14 using a chain bar 104. The chain bar 104 clamps the second end 102 of the chains 60 to fix the second end 102 of the chains 60 to the outer frame 14. The chain bar 104 can be fastened or welded to the outer frame 14.

The chains 60 include chain sections 60a, 60b, 60c, and 60d. The lower sprockets 62 include a left sprocket 62a and a right sprocket 62b. The chain section 60a extends between the second end 102 of the chains 60 and the upper sprocket 64. The chain section 60b extends between the upper sprockets 64 and the lower sprocket 62b. The chain section 60c extends between the lower sprocket 62b and the lower sprocket 62a. The chain section 60d extends between the lower sprocket 62a and the first end 96 of the chains 60.

The coupler 20 can further include one or more roller guides 106 that guide the chain 60 as the chain 60 is pulled around the sprockets 62, 64. As discussed in more detail below, the roller guides 106 can be included as part of tensioners 108 that can be adjusted by a user to adjust the tension of the chain 60. The tensioners 108 can be adjusted using a fastener 110, such as a screw, that alters the height of the roller guides 106 relative to a pivot.

Referring now to FIG. 10B, the brakes 40 can include a pedal or lever 112, a link 114, and a fastener 116, such as a pin or a rivet, fastening the lever 112 to the link 114. The inner frame 12 can include a bracket 118 to which the link 114 is fastened. The link 114 can be fastened to the bracket 118 of the inner frame 12 using a fastener 120, such as a pin or a rivet.

The brakes 40 can further include a lockout rod 122 that is fastened to the lever 112 via a fastener 124, such as a pin or a rivet. A bracket 126 includes a slot that guides the fastener 124 in the vertical direction, a leg beneath the slot attached to a pad 128, and a cup extending from the leg that capture a spring 130. The lockout rod 122 can be vertically adjusted via the lever 112 to a released position, as shown, in which the pad 128 does not engage the floor, and to a locked position, in which the pad 128 engages the ground. Friction maintains the lockout rod 122 in the locked position. The spring 130 acts against the bracket 126 and the pad 128 to bias the pad 128 toward the floor.

To set the brakes 40, the user can step on or depress the outside end of the lever 112, causing the lever 112 to rotate about the fastener 124 in a counterclockwise direction. In this regard, the fastener 124 acts as a pivot. As the lever 112 rotates counterclockwise, the fastener 124 is also moved downward in the slot of the bracket 126 due to the downward force of the lever 112. The counter clockwise motion of the lever 112 causes the link 114 to rotate in a clockwise direction. When the lever 112 and the link 114 are aligned or rotated just beyond alignment, the lockout rod 122 is friction fit in the locked position. This friction fit prevents the lever 112 and the link 114 from returning to the released position shown in FIG. 10B. In the locked position, the pad 128 engages the floor and the spring 130 biases the pad 128 against the floor.

Referring now to FIG. 11, the brakes 40 can further include a release lever 132. A user can step on or depress the release lever 132 to disengage the lockout rod 122. When the lockout rod 122 is disengaged, the lever 112 and the link 114 are allowed to return to the released position shown in FIG. 10B. In the released position, the pad 128 does not contact the floor, and therefore the step stool 10 can be rolled freely across the floor.

The tensioners 108 include the roller guides 106, the adjustment bolts 110, levers 134, and pivots 136. The chain section 60c can be routed above or below the roller guides 106, and the fasteners 110 can be loosened or tightened to adjust the height of the roller guides 106 relative to the pivots 136. Thus, by loosening or tightening the fastener 110, the user can adjust the tension in the chain 60.

Referring again to FIGS. 1 through 11, operation of the step stool 10 will now be described in detail. A user can enter the step stool 10 when the step stool 10 is in a lower position, as shown in FIG. 1. The user can enter the step stool 10 by stepping, or if the user is in a wheel chair or a wheel stand, by rolling over the ramped end 43 of the platform 42. When the user is positioned on top of the platform 42, the user can manipulate the user interface 24 to command the step stool 10 to rise. The user interface 24 communicates the user's command to the control module 22, which in turn controls the actuator 18 to raise the step stool 10 to a raised position, as shown in FIGS. 2A and 3.

With specific reference to FIG. 8A, when the control module 22 controls the actuator 18 to raise the step stool 10, the motor 76 drives gears in the gear box 78 to move the piston 82 upward within the cylinder 80. As the piston 82 moves upward, the piston 82 moves the outer frame 14 upward relative to the inner frame 12. Upward movement of the piston 82 within the cylinder 80 can be referred to as extension of the actuator 18. Downward movement of the piston 82 within the cylinder 80 can be referred to as retraction of the actuator 18.

With specific reference to FIG. 10A, as the actuator 18 moves the outer frame 14 upward, the outer frame 14 pulls the first end 96 of the chain 60 in the upward direction. The upward force on the first end 96 of the chain 60 creates tension in the chain 60 that pulls the second end 102 up the chain 60 in the upward direction. In this manner, the coupler 20 transmits the upward force exerted on the left side of the outer frame 14 to the right side of the outer frame 14, which causes the lateral opposite sides of the outer frame 14 to rise evenly.

Referring now to FIG. 12, a step stool 137 is similar to the step stool 10 such that only differences in the step stools 10, 137 will now be described. The step stool 10 can have larger dimensions suitable for industrial use, and the step stool 137 can have smaller dimensions suitable for home use. The step stool 137 includes a right handle 138, a left handle 140, and a user interface 142. The handles 138, 140 are generally tubular and have a straight pole shape that can be gripped by a user. The user interface 142 is integrated into the top of the left pillar 46 and includes a button or a touch screen. The platform 42 has a generally square shape and the control module 22 is mounted underneath the platform 42. The control module 22 can be mounted within a control box that is fixed to the inner frame 12. Operation of the step stool 137 is similar to that of the step stool 10 with the exception that the user controls the integrated user interface 142 rather than the remote user interface 24.

Referring now to FIGS. 13 and 14, a step stool 144 is similar to the step stool 10 such that the only differences in the step stools 10, 144 will now be described. While the step stool 10 includes two columns or pillars, the step stool 144 includes only one pillar, the pillar 46. In addition, the pillar 46 is not positioned near a lateral end of the platform 42, but rather is positioned near the rearward end of the platform 42 approximately midway between the opposite lateral ends of the platform 42. The step stool 144 includes the pole handle 140 and the integrated user interface 142, discussed above with reference to the step stool 137 of FIG. 12.

The step stool 144 includes a coupler 146 that couples the inner surface of the pillar 46 to the underside surface of the platform 42. The coupler 146 includes a chain 148 having a first end 150 and a second end 152. The first end 150 of the chain 148 is attached to the inner surface of the pillar 46 by, for example, a chain bar welded or fastened to the inner surface of the pillar 46 and clamping the first end 150 of the chain 148. The second end 152 of the chain 148 is attached to the underside surface of the platform 42 by, for example, a chain bar fastened or welded to the underside surface of the platform 42 and clamping the second end 152 of the chain 148.

The coupler 148 also includes a forward upper sprocket 154, a rearward upper sprocket 156, a rearward lower sprocket 158, a forward lower sprocket 160, and a middle sprocket 162. The chain 148 includes chain sections 148a, 148b, 148c, 148d, and 148e. The chain section 148a extends between the first end 150 of the chain 148 and the sprocket 154. The chain section 148b extends between the sprocket 154 and the sprocket 156. The chain section 148c extends between the sprocket 156 and the sprocket 158. The chain section 148d extends between the sprocket 158 and the sprocket 160. The chain section 148e extends between the sprocket 160 and the second end 152.

With continued reference to FIGS. 13 and 14, operation of the step stool 144 will now be described in detail. When the user commands the step stool 144 to rise via the user interface 142, the actuator 18 extends to exert an upward force at the top of the pillar 46. The pillar 46 transmits this upward force to the first end 150 of the chain 148, which creates tension in the chain 148. This tension extends through the chain 148 from the section 148a, to the section 148b, to the section 148c, to the section 148d, and finally to the section 148e. As the tension is transmitted through the sections 148d and 148e of the chain 148, an upward force is exerted on the sprocket 160. In this manner, the coupler 148 transfers the upward force exerted by the actuator 18 onto the pillar 46 to an upward force exerted on the forward end of the platform 42. Thus, the coupler 148 ensures that the longitudinal ends of the platform 42 are evenly raised.

The foregoing description of the embodiments has been provided for purposes of illustration and description. It is not intended to be exhaustive or to limit the disclosure. Individual elements or features of a particular embodiment are generally not limited to that particular embodiment, but, where applicable, are interchangeable and can be used in a selected embodiment, even if not specifically shown or described. The same may also be varied in many ways. Such variations are not to be regarded as a departure from the disclosure, and all such modifications are intended to be included within the scope of the disclosure.

Claims

1. A step stool, comprising: an inner frame including two inner pillars;an outer frame including two outer pillars attached to a platform near opposite ends of the platform and configured to receive the two inner pillars;an actuator coupled to one of the two inner pillars and one of the two outer pillars, and operable to raise the outer frame relative to the inner frame; anda coupler that couples the two outer pillars to each other to evenly lift the opposite ends of the platform when the actuator raises the outer frame.

2. The step stool of claim 1, wherein the coupler includes a chain meshed with a sprocket, the chain having a first end fixed to a first of the two outer pillars and a second end fixed to a second of the two outer pillars.

3. The step stool of claim 2, wherein the chain and the sprocket are arranged to transmit an upward force on the second of the two outer pillars when the actuator exerts an upward force on the first of the two outer pillars.

4. The step stool of claim 2, further comprising a tensioner adjustable to adjust the tension of the chain.

5. The step stool of claim 1, further comprising a sliding mechanism including a first bracket, a second bracket, and a bearing, the first bracket mounted to the inner frame, the second bracket mounted to the outer frame, and the bearing positioned between the first bracket and the second bracket.

6. The step stool of claim 1, wherein the actuator includes a motor, a cylinder, and a piston, the motor operable to slide the piston within the cylinder.

7. The step stool of claim 6, further comprising a control module and a user interface, the control module controlling the motor to raise and lower the platform based on commands received from a user via the user interface.

8. The step stool of claim 7, further comprising an object sensor mounted to the inner frame, wherein the control module stops the motor when the object sensor senses objects beneath the platform.

9. The step stool of claim 1, further comprising a handle on each of the two outer pillars.

10. The step stool of claim 1, further comprising wheels coupled to the inner frame that enable a user to roll the step stool to a desired position.

11. The step stool of claim 10, further comprising brakes that prevent the wheels from rolling.

12. The step stool of claim 1, further comprising a brace mounted to the inner frame and engaging the actuator to prevent the actuator from tilting.

13. A step stool, comprising: an inner frame including a single inner pillar;an outer frame including a single outer pillar attached to a platform near a first end of the platform and configured to receive the inner pillar;an actuator coupled to the inner pillar and the outer pillar, and operable to raise the outer frame relative to the inner frame; anda coupler that couples the outer pillar and a second end of the platform to evenly lift the first end of the platform and the second end of the platform opposite the first end of the platform when the actuator raises the outer frame.

14. The step stool of claim 13, wherein the coupler includes a chain meshed with a sprocket, the chain having a first end fixed to the outer pillar and the second end fixed to the platform.

15. The step stool of claim 14, wherein the chain and the sprocket are arranged to transmit an upward force on the second end of the platform when the actuator exerts an upward force on the outer pillar.

16. The step stool of claim 15, wherein the sprocket includes multiple sprockets and one of the sprockets is position at the second end of the platform.

17. The step stool of claim 16, wherein the upward force on the second end of the platform is transmitted through a pivot of the one of the sprockets.

18. The step stool of claim 13, further comprising a control module and a user interface, the control module controlling a motor to raise and lower the platform based on commands received from a user via the user interface.

19. The step stool of claim 18, wherein the control module is mounted to the inner frame underneath the platform and the user interface is integrated in the outer pillar.

20. A step stool, comprising: an inner frame including two inner pillars;an outer frame including two outer pillars attached to a platform near opposite ends of the platform and configured to receive the two inner pillars;an actuator coupled to one of the two inner pillars and one of the two outer pillars, and operable to raise the outer frame relative to the inner frame;a slide mechanism including a first bracket, a second bracket, and a bearing ball, the first bracket mounted to the inner frame, the second bracket mounted to the outer frame, and the bearing ball positioned between the first bracket and the second bracket; anda chain and sprocket mechanism that couples the two outer pillars to each other to evenly lift the opposite ends of the platform when the actuator raises the outer frame.