mwt UBUG 4.1 tribute (Tribute)

     This page is all about my attempt to replicate one of my favorite robots, UBUG 4.1.  This particular robot was designed by Mark Tilden and is a two-motor walker that uses a master-slave bicore for control.  I have had trouble finding documentation on this particular robot so I've been forced to make some educated guesses in many parts of my design.

mwt UBUG 4.1 tribute

The original UBUG 4.1       My plans for Tribute   
By Mark W. Tilden                                          

Initial Leg Design
     This is the first pair of legs I made for the project.  After framing up the motors and playing with the legs, I found that the balancing point was not just right.  The front legs were too narrow for their length.  I also made the decision to go with some Sanyo gearmotors instead of the Nihons seen here.

The first set of legs supported by an iPod power adapter

Tribute PCB
     I decided that a professionally made PCB would give me the look I was going for.  I designed the PCB using ExpressPCB and tried to emulate Tilden's original UBUG shape and size.  The first two pictures are of the layout.  The left PCB picture is without a solar engine while the right has a Miller Solar Engine attached.  Each board has to be cut between the bicores and the solar engine and bent upwards to emulate UBUG 4.1's design.

ExpressPCB layout.  The second of the two has a Miller Solar Engine Included

My first populated PCB

My second PCB; this one has most of the components mounted on the top of the board.

PCB with legs for size reference

Tribute Chassis
     Here are some pictures of the chassis for Tribute.  The motors are held in place by CA glue between two plates of brass.  I used a power drill and Dremel tool to shape the pieces and a small vice for bending them into shape.  I placed a third piece of brass on the top of the chassis that extends a little beyond the end of the front motor.  This piece will be the mechanical stop for the front legs, keeping them from hitting the PCB and from getting too far off center.  I soldered both ends of the mechanical stop to the top for extra strength.

Finished chassis complete with two 1F Caps

Final Body Assembly
     The chassis is secured to the PCB with a bead of hot glue.  The hot glue holds the PCB securely enough to the chassis so as not break off but can be removed without harm if necessary (CA glue tends to crack and leaves residue when removed).  To mount the solar cell, I soldered two 1/16" brass rods to mounting holes on the PCB.  I bent the rods to give the solar cell a gentle slope towards the front of the robot.  This was mainly for aesthetic purposes but also increases the efficiency of the cell when the robot is heading towards light.

The completed body

Solar Cell Assembly
     Here is the finished solar cell.  I glued a stainless steel plate to the back of it to protect the fragile solar membrane.  The stainless piece glues to the two brass mounts on the body with hot glue, making a strong but removable connection.  It necessary the solar cell can be removed by simply peeling off the hot glue and disconnecting the pins from the sockets on the body.


Final Assembly
     Here are some pictures of the completed robot.  Everything went together beautifully and is holding up very well.  I am extremely happy with how the robot came out and can not wait to build another.