Agribot IX

Agribot IX

The team demoed the agribot today at TI. (Juan, Guang, and Alex above)  Progress on the Android and iPhone apps is looking good as you can see from the screen shot below. The collision avoidance worked "OK" in this hallway - although the metal in the environment kept throwing off the e-compass. The GPS was a little bit off - but in the right general location.

Agribot VIII

Agribot VIII

Our Agribot team has been making good progress. In this video, Juan Wu(who has recently joined the team) is putting obstacles in front of the small scale robot as it tries to navigate to a specific GPS location.  As you can see, there are still some improvements to be made, but the bot keeps going. 

Once the team is satisfied with the performance of the small scale robot, the work will focus on the larger scale robot in an agricultural setting(row crop).  One of the issues we're hoping won't be an issue in the field is e-compass error due to metal in the environment.

Agribot VII

Agribot VII

We had two new members join the team today. Kelvin, who will be working on the server side of things - and Alejandro, who will be working on the Android version of the app.  Our  team is excited about the project and is focused on building a complete UI demonstration with maps and selectable navigation points within a few weeks. We're working on a DRV8432 boosterpack (with Masterspy) that should be capable of driving larger motors (14A peak) in parallel.

Agribot VI

Agribot VI

Guang Zhou and Seungcheul Kim(from UTD) are holding a miniature version of the agribot they've built for testing their navigation software and iOS app.  Their app enables any iOS device to control and share resources(such as GPS/maps/etc.) with the agribot via the CC3200's Wi-Fi connection.(making it a "phone drone")  They are using the boosterpack developed by the Wi-Fi IoT team with integrated motor drivers to control the car and interface with a servo mounted ultrasonic sensor.

Once we complete development of their GPS + Ultrasonic navigation software for the agribot, we plan to launch a Kickstarter project(with some other contributing students) offering an agribot controller(with application) and a hardware kit (to build a full scale agribot).  You can find our opensource navigation software project here: https://github.com/gzhou358/Agribot_v1.0  

Agribot V

Agribot V

We've wired the rekam1 board into the agribot and test driven it around the drive way. As you can see, there are just four wires connected to the board: 6V, GND, pin 18 gated GND, and pin 19 gated GND. We ran the two gated grounds through a kill switch for safety. You'll notice the battery is at the opposite side of the bot to counterweight the bucket (which is 90 pounds).

We're running the bot backwards at low speeds since the bucket has a tendency to nick your heels if you're not careful ;) . We've ordered another linear actuator rated for 225 pounds at 12V. We plan to experiment with it at 6V, and if it's not powerful enough, go to a 12V system with a smaller bucket.

Agribot IV

Agribot IV

We put this bucket on the agribot and tried moving it with a channel iron torque arm and linear actuator. Although the bucket is handy, it was too heavy for these little actuators (even with leverage). We decided to see if we could find someone to help us weld a smaller and lighter bucket. As we counter-weighted the bot, we realized these tires were too thin for outdoor applications - so we'll need to explore some fatter tires.

Linear actuators like the one above aren't cheap, so we're exploring homemade alternatives.

Agribot III

Agribot III

Here's an updated demo of obstacle collision avoidance using ultrasound. In this demo, the car is programmable via Wi-Fi using CC3200 and uses an ultrasonic transducer to sense and avoid running into objects in its programmed path.

In agricultural applications, the robot would use a programmable GPS-based path and would use the ultrasonic sensors to correct its path while navigating along rows of crops.

Agribot II

Agribot II

Flashback to linear actuators! We've harvested this two relay system with actuator from the Chickenator(since the chickens have figured out how to open their own coop in the morning). We're planning to use this to drive the front loader shovel on the agribot.  We have no idea how well it will work, but we hope to get this 4 cubic foot bucket in on Wednesday to start experiments.  We've decided against the pruning attachment after a few simple experiments resulted in the destruction of some otherwise healthy vines.  We'll focus on shoveling compost/mulch/etc. and fumigating for now ;)

Power relays have a normally open(NO) and normally closed(NC) contact. Int the above wiring, We've connected the NC to NO contact of one relay and connected this to ground.  We've connected the remaining NC to NO contact of the power relays together and to 6V.  The center taps of the power relays are connected to the positive and negative terminals of the linear actuator.  The linear actuator is driven by a DC motor which turns a screw that pushes or pulls a smaller rod through a larger diameter piece of metal. We've connected pin 2 and pin 15 to the inputs of each power relay.

put 2 0

put 15 100

causes the linear actuator to move in one direction until it's limiter switch turns it off.

put 2 100

put 15 0

causes the linear actuator to move in the opposite direction until it's limiter switch turns it off.

(if both pin2 and pin15 have the same PWM(pulse width modulated) voltage - nothing happens)

Agribot I

Agribot I

One man's trash is another man's treasure! We've been playing around with electric wheelchairs for a few years now and part of the problem we've had is in getting the parts we wanted for our prototypes. You can find these things all over ebay in the $150 range with the only problem being that the sellers want you to pick them up and they're not nearby.  We started making some simple offers like: "Ship us the wheels and motors and you can keep the rest of the chair" - and voila: an aftermarket for government sponsored healthcare is born!

We're going to take you through the process of converting these parts into a programmable agricultural robot. The goal of this project is to have the agribot automatically navigate up and down a vineyard or field while spraying and pruning the plants.

Most electric wheelchairs will operate from two 12V batteries(24V total) located in the base of the chair.  We're going to operate the system off a single 6V golf cart battery because we don't need it to go very fast but we do want it to last a whole season on as few charges as possible.  Since we're operating on a relatively flat surface and we won't have 24V to operate the solenoid brakes on the motors, the first thing we're going to do is remove the electric brakes on the back of each motor(search for youtube video on how to do this). (if you are operating on a slope, you might want to keep the brakes and operate your system at a voltage high enough to disengage them).  The motors won't turn until these brakes are activated or removed.

The second thing we're going to do is attach the motors/wheels to a board (or use an existing wheel base). We'll be experimenting with ultrasonic sensors to detect the distance of the agribot from the vines.  We will likely use GPS to navigate and Wi-Fi to program and activate(or override) the agribot.  We also hope to integrate a battery powered sprayer and pruning attachment.  If you decide to build your own agribot, it's important that you operate it in a fenced or caged environment since a robot of this size with a pruning arm and fungicidal spraying attachment isn't a toy.