Control

Robot Configuration

The final prototype of the robot used 6 bladders. This was a problem because the control board was designed with 4 outputs. Modifying the control board to have more outputs was not economical. To work around this, two outputs were shared between 4 bladders. However, this meant that the robot could not be operated to its fullest capabilities without changing the tube configurations. All of the functions of the robot are split between two configurations.  

Configuration 1 connects the two halves of each bottom bladder. This can be done by either connecting the front and back of the robot with a Y fitting or by using the second prototype bladders.  As a result, in this configuration the front and back of those bladders cannot be operated independently.  

Configuration 2 connects the two front and two back halves of each bladder. This is best done with Y fittings.

A potential upgrade to the control panel is to add outputs to the board. If the board had 6 total outputs, the different configurations would be obsolete, and FRCMR would be able to go from turning to climbing through simple bladder inflation changes.

Robot Controls

Pressure sensors: The programming for the robot is very simple. The robot uses a bang bang control to regulate pressure in the actuators. If the pressure in the bladder is lower than the desired pressure, the valve is opened. If the pressure in the bladder is larger than the desired pressure, the valve is closed.

The pressure sensor is located next to the manifold. When the valve opens, a wave of high pressure air travels through the tube. Due to the sensors' location, the high pressure wave was detected before it reached the bladder. This resulted in high pressure readings that closed the valve prematurely. To mitigate this, the tee fitting was relocated as close to the robot as possible. This resulted in much more accurate pressure readings.