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The spiderbike linkage is a basic concept similar to a wheel made out of stone. Wheels today are still round but improvements in materials, construction, drive train, braking, and suspension have increased their usefulness and efficiency. They are used on a wide spectrum of things from small toys to huge pieces of mining equipment. This linkage will evolve in much the same way. Different uses will have different requirements that will drive modifications and advancements. Some of the obvious ones are listed here.
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Foot Design
There will be a general-purpose foot designed for a variety of terrain types that could handle sand, rocks, or pavement. Specialized feet will be developed to target specific conditions such as sidewalks, curbs, or stairs and for amphibious vehicles that are expected to travel in wet marshy areas or extreme rock climbing vehicles requiring more traction.
Suspension
There are several areas that could be utilized for adding suspension. The foot, leg, shock absorbing links, or attachment points to the frame are several possibilities.
Collapsible
The frame and legs for small and mid-sized applications would benefit from a collapsible configuration to increase options for storage and delivery to target. A parallel linkage between the frame and each pair of legs similar to ATV suspensions could be exaggerated to allow the legs to fold up against the body when fully lifted.
Amphibious
The legs can function as oars enabling the vehicle to paddle in the water. This could be a passive design such as fixed canards, hinged flaps, or openings designed into the legs that would minimize the drag during the forward stroke on the portions of the leg that are not lifted above the waterline and take advantage of the motion of the leg on the return stroke to propel the vehicle forward. A midpoint on the foldable suspension mentioned above would position the legs to optimize the movement of the legs when rowing. A walking machine with the ability to climb over obstacles and swim across rivers would eliminate many of the restrictions of conventional vehicles.
Leading Edge Spurs
Teeth on the front edge of the legs allow the spider to step onto obstacles taller than it's step height, the highest point of the foot during a cycle. The downward motion of the leading leg will lift the body of the device if the spurs remain engaged until the paired leg contacts the obstacle and continues to increase the overall center of gravity.
Trailing Undercarriage Spurs
A single large protrusion on the trailing edge of each leg, if appropriately designed, would enable the vehicle to crawl over obstacles that would otherwise limit it based on ground clearance. The translation and rotation of the leg during the propelling portion of the cycle can be transferred with this modification.
Spring Assist
The use of springs to counter balance the momentum of the legs as they move throughout the cycle would have benefits. The ideal configuration would use springs with the appropriate stiffness to create a system at resonance for a specific target speed.
Buckling Leg
Toys would benefit from a leg that would unsnap or provide spring-loaded relief when stepped on or dropped. Larger vehicles could be designed with shear pins or breaking points that would minimize structural damage during collisions, jumps and falls.
Hybrid Legs
Additional degrees of freedom could be added to the device by controlling the length of various links with actuators. The added complexity could have benefits. It would allow for precision placement of the foot, increased step height, and still allow high speed traveling when the standard length is locked in.
Speed-Leveling Drive Train
The variation in the speed of the foot for a constant rotational speed of the crank is not desirable. A variable crank rotation that could compensate for these differences as well as the mechanical advantage needed when stepping onto obstacles would minimize the stresses on the drive trains of larger vehicles.
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© 2008 Klann R & D, LLC All rights reserved
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