Week 13 - October 3-9

Power Module

This week began with designing and building an initial circuit that would connect the battery to the Cart’s circuit as well as to close the line for charging the battery with a system built into the Cart. One of the main components required for this to work is a toggle switch that will flip the battery’s connection from the circuit to opening it and keeping the system off and switch it to prepare to charge. Two terminals on the switch connect the line between the central terminal one at a time and moving the switch from one side to another closes the connection, while the middle opens both sides. The idea of using this switch is to allow either the circuit between sensors and motors connected to the battery or the charger connected once at a time. Also to help visually verify the charge an 12V battery indicator display was purchased to help give a visual status of what the battery charge is immediately for the user to see. Figure 1 shows the initial circuit designed with the toggle switch connecting both the battery charger and the terminal blocks for circuit powering. Figure 2 shows the indicator display.

Figure 1: Initial circuit connecting both terminal strips for the cart and battery charger to the 12V battery using a toggle switch.

For wiring and powering, a circuit diagram will be drawn up this week to help give an idea of how all components should be physically placed onto the cart’s shelf that will house all hardware. Research is also being currently done this week to look at how to implement a way for the code to watch the battery’s charge in order to alert when the battery is low.

Figure 2: LED battery charge indicator

Control Module

The IR transceiver was integrated into the Arduino board and code was fixed to help guide the rover to the user’s IR transceiver. As of now while the cart does not detect the IR signal it will “guess” the user is in a certain direction by moving forward and observing the signal strength change. If the signal increases it will continue to move forward, and if not, turn and test a new path, etc. If the IR signal from the user’s transceiver is detected, however, the cart will turn despite the signal strength because now it has the direction of the user. The cart’s new goal will be to make the “North” IR transceiver sensor be the only one detecting user’s IR signal and then move toward the user either until target signal strength is achieved, an obstacle is detected, or user’s direction has been changed to another side. The cart should after that adjust its path again accordingly and repeat the above actions.

While it is a specification, it should be noted that for proper use the user should at all times of the following operation keep both their phone with the app connected and the IR transceiver on them at all times, else the cart will definitely give incorrect responses to what was expected.

A very brief but initial test of all systems running in the control module was held, and for the most part all hardware and sensors reacted as expected. When given the proper conditions, the cart reacted to the need to turn to keep the user in front of it and paused following to avoid obstacles. Of course due to the cart not being built, three LED’s representing the direction the cart would be taking (left, right forward) represented what its reaction was to commands or sensors. The cart would light the respective LED to show it understands it needs to keep turning WHILE watching for obstacles until the user’s IR signal is in front of it, and then carry on moving forward. When connecting everything to the motor drivers and rest of the cart, the timing and reaction will need to be adjusted to fit the real-world application of the cart’s turning and object detection-reaction, as well as the rest of the sensors giving the proper response. But the template is complete as far as the software goes, all that is left is to expand the level of object avoidance with the other sensors and scenarios it will face.

One thing that will need to be observed is the cart’s line of sight between one IR transceiver to another, it may be needed to be tested in other, more open scenarios as the distance range has not truly been maxed out and therefore cannot be actually verified. From what was seen in this last test the cart would require a more direct line of sight to the IR signal the farther away it is, but it can still see the user’s IR signal from at least 10-15ft away.