The simplest design that first comes to mind is stacking simple revolute joints as close as possible to each other and this led to the actuated universal joint design. As the name suggests, he design incorporates a universal joint with two motor to actuate each of the two degrees of freedom of the universal joint. There are many variations of this design: The simplest of which is just stacking revolute joint orthogonally and as close to each other as possible, as seen in Figure 1. These kinds of designs tend to be bulky and slow, hence not appropriate of lots of snake robot applications.

Figure 1: Double orthogonal revelute joint.

Another varriation of this design approach is by using bevel or worm gears train as seen in Figure 2 or using push-pull rods, Figure 3.

Figure 2: Using worm gears.

Figure 3: Push-pull design approach used in EOD snake robot..

The main challange in this design approach is to make the joint as compact as possible, yet strong enough and with appreciable bending range. One of the main benefits of this design is that you need only one motor to actuate one degree of freedom as oposed to the rest of designs in the webpage where two motors are actuated at all times. However, the torques transfered to the motor are relatively larger hence the need of higher reduction. Usually the high reduction is done by using power screws of worm gears hence the slowness of the mechanism.

• Howie Choset: Advisor
• Elie Shammas: Graduate Student
• Ben Brown: Idea, Design, Engineering Drawings
• Al Costa: Electronics and PIC programming.
• Sean Pieper: Electronics and PIC programming.
• Electrical Engineering Shop: Manufacturing