Weekly update: Week 9

We completed a new motor mount without a crack. The bends look a lot more precise in this one than the last one.

Newest mount with motors

The group also lathed the bushings out of billet aluminum. Now they need to be drilled to the proper size on the inside and another hole drilled on the side and tapped to hold the set screw. The set screw will be used to hold the busing/wheel to the shaft.

Lathed bushings

Close up view

Weekly update: Week 8

Finished line bending the motor mount.

Bracket with the bottom plate

Bracket with both plates and motors

Robot resting on ball without wheels. With wheels on, the plexiglass will not contact the ball.

The group had some trouble with a corner cracking. Decided to start making a new one with the other plexiglass cut out we had.

This is a detail of the crack in the motor mount. It was caused by an uneven tightening of the screws that hold the motor to the mount.

Weekly Update: Week 7

Machined thicker, wider acrylic. thickness = .118 " and width = 39 mm

This week: Machined with thicker plastic, worked on bushing for motor to wheel contact, started hot wire bending, microcontroller research

Total machining time for the laser cutter ( for top platform, bottom platform, and 2 brackets) = about 30 minutes


Machining Process Documented:

Main screen of CorelDraw(laser cutting software) and Top Platform cutting

Cutting circles out of the main brackets

Started working on bending the material into shape with the hot wire bender:

Upper platforms assembled:

Assembled platforms next to bocce ball for comparison:

Bending process in action: 

Closer view of bent corners:

Electronics Circuit

The group looked into how to provide power to the circuit. They found out that the Arduino UNO controller they had been considering using draws 7-12v. The motors draw 2.7v and the uno only outputs 5v. To run all three motors each one will have to be run through an A4988 stepper motor driver carrier, available from pololu. This device can receive logic voltage commands from the arduino but also receives voltage from the power supply to power the motors. It uses between 8 and 35v. We need three of them, one for each motor. The motors then get their power from the batteries, using the motor driver as an intermediary. The motor driver receives a logic voltage from the micro controller that regulates how much voltage to run to the motors.

Week 6 Update

Week 6 update:
revised cad drawings
parts arrived
machine shop work



The cut acrylic: the holes are cut through, and the lines are etched for the line bender.

Bocce Ball next to the motor for size comparison

Motor closer up pictures (35mm x 35mm x 36 mm [depth]) M3 screw holes

Wheel side view.





















Wheel top view.





















M3x 6 screws ( slightly too long for our motors- ordering M3x5)

Holes are slightly misaligned due to an cad error. Model revised and holes now match. Etching (for bend lines) showed up well, and are correctly spaced.

2 more views of the plate against the motor.

View of the inside diameter of the wheels versus the motor shaft. Working on lathing aluminum to press fit between the shaft and wheel. 

Ball Contact: Coordinates

           As we begin the construction the general frame of the Ball Balancing Robot, it is essential that one gathers as much information as possible. An important piece to the construction is to find where the ball is in contact with the motors. In finding the point of contact we can begin sketches and construction around these three important coordinates.

          These coordinates could be easily found by using a series of algebraic moves. By knowing the angles that separate each motor in three dimensional space and the radius of the ball these coordinates can be solved for.

          The following work is shown below: