Integrated System Build & Test
Table of Contents
Team Vision for Integrated System Build & Test Phase
The purpose of this phase was to continue building with an emphasis being placed on integrating the subsystems into the final product.
Project Build Status
The guides have been fully glued and cut. They are in the process of being attached to the floats with wood glue.
Each pair of floats has been glued together using E6000 adhesive. Industrial velcro was applied to the floats as well as the bottom of the frame to allow easy assembly and disassembly for transportation and storage purposes.
The frame was completed in the previous phase, however, a new attachment method was constructed and installed for two of the docking ports. See 'Insufficient 80-20' in problem tracking.
The attachment mechanism was not significantly changed during this phase. Mounting methods were finalized and installed.
The RCS PCB finally came in and was assembled within a day, and tested well on its own. It has yet to be tested with the switches, batteries, etc all attached.
The Robofish power distribution PCB was assembled shortly after the RCS PCB and tested well, with the exception of the actual charging of the LiPo battery, due to problems with the RCS batteries detailed in the next section. The relays controlling the switches operate perfectly as does the relay controlling power distribution.
The RCS batteries inherited by our project seem to be badly damaged, or potentially just unable to hold a charge. When attempting to power the LiPo charger on the fish through the power distribution PCB, the voltage droops down below the acceptable lower limit for the LiPo charger, and it fails. We are working on refurbishing our LiPo batteries in order to get it working, but we may have to acquire a replacement set of lead acid batteries.
RCS Arduino Program
A program was written in Arduino where the motor is driven in either direction accordingly. When the Robofish comes in to dock and flips the microswitch, the motor is driven forward to tighten the screw to secure the Robofish.
Once the Robofish has completed charging, the motor is driven backwards to unscrew, releasing the fish. An emergency stop and release button has been implemented which can be pressed manually to forcefully stop the RCS to halt its current mode of operation and release the fish.
A voltage divider has been implemented on the circuit board to reduce the 12 V connection detection from the fish down to approximately 5 volts. The resistors used are 4.67 kohms and 8.1 kohms. The reduction is carried out since the original voltage exceeds the capacity of the Arduino which is 5 volts.
When the reduced 12 V connection is detected on the Arduino, the motor driver will continue screwing in the forward direction for a set amount of time determined in the code before stopping. This is done to ensure that the motor does not screw the beyond the strain of the container. Over-screwing may cause undesired results such as cracking and deterioration of the container.
The counter as illustrated on the software flowchart is partially implemented but commented out due to uncompleted coding.
Robofish Arduino Program
The relay control was implemented on the Robofish, where it is connected to the balance board. Having done so will help maneuver the control buttons in order to activate the charging from the Robofish side of the process.
The code below in C++ performs this:
The Issue Management System can be downloaded Here.
The team did not have enough of the provided 80-20 to bridge the gaps and provide mounting for the two of the connector assemblies. To rectify the problem, aluminum pipe was attached across the gap. 'U' clamps have been installed to secure a connector assembly mounting plate to the pipe. The clamps utilize a rubber pad to prevent slippage on the pipe and secure to the mounting plate with two screws.
This problem only affected the two connectors located at the docking ports on the longer sides of the RCS (Ports 1 & 3). The other two connectors are still mounted on 80-20.
The pool has been closed for a few weeks as it is in need of repairs which are supposed to be completed by 3/22/17. These closures have impacted our ability to perform testing, as we don't have a suitable testing environment in the cold weather. Once the pool is opened, the team will perform testing immediately.
Micro-switch Attachment Stop
The release of the micro-switch during the attachment process proved to work inconsistently. This is likely a result of the connector design and could be solved with increasing the size of the hole that the switch releases into upon attachment completion. However, the simpler solution was determined to be the implementation of an electrical stop. The new process will proceed as seen below:
The attachment screw continues turning for several seconds after the electrical connection is established to ensure the electrical connectors are fully inserted. The spring inside the connector on the fish allows this to occur by providing about an inch gap between the nut and connector wall. This gap prevents the system from binding/seizing due to over-torquing the attachment screw.
The wire reparations of the Robofish has been completed as of 3/21/2017. This includes connecting the system to the balance board, relay control, dc-dc converter, and the battery. However, this does not include integrating the system with connecting it to the RCS, and only includes the Robofish's side of the charging process. More is to be completed soon.
A more up to date schematic and pinouts will be provided to reflect the fixation more accurately.
- The largest risk for the RCS is that the guides do not effectively locate the Robofish into the docking ports. This risk has grown as the construction process progressed. If this risk develops into a problem, options are being considered to make the surfaces smoother (plastic sheet) or the angles more dramatic.
- Another major risk is that the state of the Robofish is still uncertain. It was been completely re-wired, and powered on successfully, but the functions of the valves and pumps have not been tested yet. This also includes the functions of the image-processing and how it integrates with the charging process.
- It was discovered during integration testing that a single lead acid battery is not able to source enough current to charge the fish without having its voltage drop unacceptably low (less than 10 volts). Due to slow charge times, we have as of yet been unable to test with all four lead acid batteries in parallel, but we hope this will allow the charger to function. If the batteries are too degraded to hold a proper charge, it may be necessary to acquire new batteries, or devise a replacement power storage system (impractical).
We have fallen behind in certain areas. The chart below shows most major overdue tasks:
A meeting will be held next class period (3/23) to determine the cause of the delays and hopefully address them to improve future performance.