User:Acheung17/PowerWheel2

Project Preference

 * 1) Autonomous Power Wheel
 * 2) Smart Shoe
 * 3) Mobile Robot Hallway Navigation

Problem Statement
''In one or two sentences, describe the project that your group will be working on. Identify what CDIO phase (Conceive, Design, Implement, or Operate) your group will complete in this project cycle.''

Project Plan
Briefly describe your group's plan for the next 4 weeks, including major tasks that will be completed each week.

Week 1 Narrative
This week we measured the time to make for the power wheel to make a full turn. It completed a 360 degree turn on average 12 seconds. With this information we can time how long the Power Wheel needs to execute a turn. The planned path we are going to implement will be a square. It takes on average 12 seconds to make a 360 degree turn, for a square we will need only 90 degree turns. That will be 3 seconds the Power Wheel will need to turn. We need to take into consideration the time for the actuator to turn the steering wheel, which will affect the timing needed to turn.

I also came up with a supply list for the project and we will buy them for the following week. The plywood will be for the platform in the Power Wheel. The wood screws will be for assembling all the parts. The U brackets will be used to attach the lever to the steering wheel. We will need an extra 12 volt battery to test if the charger we have is broken or not, or if we need to buy all new batteries.

Supply List
 * 1) 3/4" Sheet of Plywood
 * 2) 12 Volt Battery
 * 3) 1 1/4" Wood Screws
 * 4) (2) 2.25" U Brackets

The batteries we have in the workshop are still not full charging. We have charged three batteries and they only hold a 6 volt charge. We checked the charger and it seems to be set properly at 12 volts and charged each battery over 24 hours, which should give ample time to fully charge. To see if the charger was manufactured correctly we switched the charger setting to 6 volts and will check back next week to see if it works. Also we will be buying another 12 volt and see if the charger will be able to charge the new battery.

Week 2 Narrative
This weeks goals was to adjust coding for the timing of the pedal pusher, show an example of the functioning pedal pusher on the table top mock prototype platform depressing the mock gas pedal, finalize the design for the In-Car Platform for the Power Wheel, build the In-Car Platform, and calculate the wedge height for the steering actuator assembly.

Pedal Pusher Example

The pedal pusher code in arduino needed to be changed to adjust the timing of the pedal piston. The motor needs 1.5 seconds to fully depress the motor and 1.5 seconds to release the pedal. The code was change to reflect these measurements.

Video of Pedal Pusher Assembly

Finalized Design for the In-Car Platform for the Power Wheel The platform had to have certain criteria that was set by past groups on the different features and its function. It needs to be attached only with the wing nuts installed previously on the mounting platform of the power wheel, it needs to allow access to all functions of the power wheel, and cannot modify the structure of the power wheel.

The the floor of the Power Wheel is un-level and has two different heights, and an irregular shape. To make the platform stable we decided to build the platform so it is contact with the floor, to prevent shaking and make it stronger structurally. We built it in two parts: an L shape top tier, to be attached to the mounting platform, and a lower square platform, attached with wooden blocks. The upper tier was to have 4 holes drilled in to allow access to the nuts from the mounting platform. Construction for the In-Car Platform for the Power Wheel

After the design was finalized and approved, the platform could be constructed.

The platform was built using 1/2 inch plywood and was assembled with 1 1/4 wood screws. There were difficulties with the accuracy of the measurements of the upper tier and the holes needed to access the bolts on the mounting platform needed to be re-drilled, but the platform is fully functional. The lower tier needed to be attach with a wooden block, since the height need for the block to fill in the space between the two tiers was of irregular height, two pieces of wood needed to be attached together and used as the block. The two tiers are attached with a wooden block made from a 2x4 piece of wood and a 1/4 inch piece of plywood. It is screwed together with wood screws. Wooden Wedge Calculations.



The Steering Assembly needs a wooden wedge to raise the height of the miniature linear actuator to the proper height to attach to the lever arm. The wooden wedge need to have a flat base to attach to the platform and needed to have an angled top that matched the angle of the steering wheel in relation to the floor of the Power Wheel. The height of the platform is important and needs to be correct height so when the steering wheel is in a neutral position, steering straight, the miniature linear actuator is mid stroke, extended to 70 mm.

The height of the Steering Wheel in relation to the mounting platform is 17.5 inches, the wooden mounting platform is made from 1/2 inch plywood, so the height from the platform to the steering wheel is 17 inches. The measurements for the angle of the steering wheel is 50 degrees. Using:

17 inches * Csc 50° = 22.1919 inches

I calculated the total length from the center on the steering wheel to the floor of the platform at 50°. Then subtracting the length of the miniature linear actuator half extended, 207 mm for the shaft and 70 mm for the shaft.

207 mm + 70 mm = 277 mm

277 mm = 10.9055 inches

22.1919 inches - 10.9055 inches = 11.2864 inches

I calculated that the length of the mid point on the angled face of the wooden wedge to the floor of the platform on 50° angle will be 11.2865 inches. Then using the trigonometry function Sin:

11.2864 inches * Sin 50° = 8.6521 inches

I have the height of the wooded wedge, 8.6521 inches.

Week 3 Narrative
This week the group need to update the Arduino code for linear actuator and screw motor, and measure the time for the miniture linear actuator to extend and retract. My personal goals were to change the steering lever design, calculate steering lever length, build steering lever, build wooden wedge for table top prototype, and build wooden wedge for power Wheel.

Miniature Linear Actuator

To test how long it took to extend the miniature linear actuator we inserted the positive and negative connections into the power source and timed how long it took to extend from being fully retracted.

The average time to extend fully was 14.15 seconds. To take into account for human error and the limitations of the measuring tools used to time the miniature linear actuator, 14 seconds will be used as the time to extend the miniature linear actuator. The miniature linear actuator extends a total of 140 mm and the time to be fully extended is 14 seconds, it is calculated to extend at a rate of 1 centimeter per second.

Arduino Code

The code was changed to add on the miniature linear actuator. Now the code depresses the pedal, and then turns the steering wheel from the neutral position to the left, to the right, and then back to the neutral position, and then releases the gas pedal.

Here is a link to the video of the miniature linear actuator and the screw motor working on the table top prototype. Table Top Prototype

Steering Wheel Lever Design

I had to change the original steering wheel lever design, due to the lack of supplies. Original design used a a 3 centimeter wide U bracket and wood screws to attach the lever to the steering wheel, but the largest bracket that could be obtained was 2.54 centimeters. The smaller brackets had holes that were placed wide enough to accommodate the steering wheel, but due to the size of the bracket it could not reach the lever to use wood screws to attach. To attach the lever to the steering wheel, the wood screws were replaced with 3 inch long bolts. The bolts had enough length to bridge the gap between the bracket and the lever.

Steering Wheel Lever Length

To find the the length needed for the steering wheel lever, measurements were taken from the table top prototype of the angle of force when the steering wheel was turned.

The steering wheel is 22 centimeters wide and when the steering wheel lever was attached it added extra length to the steering wheel to allow room for the attachment hardware. For the length of the steering wheel lever, 14 centimeters was chosen because of the the constraints of the steering wheel and that it gave adequate amount of force need to turn the steering wheel with the shortest lever length.

Steering Wheel Lever Construction

The lever was constructed from 1/2 inch plywood. It is attached to the steering wheel with 3 inch bolts and nuts. The overall length of the steering wheel actuator is 28 centimeters.

Wooden Wedge

To measure the height of the wooden wedge, the miniature linear actuator was attached to the steering wheel lever and extend half way, then the distance from the base of the miniature linear actuator to the base of the platform was measured. It was 1.5 inches in for the table top prototype and 2.25 inches for the Power Wheel. The bottom of the wooden wedge needs to be cut level with the platform to allow secure attachment. The top of the wooden wedge needs to be cut at 50° to match the angle of the steering wheel. The mounting bracket for the miniature linear actuator will be attached at the center of the wooden wedge with a screw.

Week 4 Narrative
This weeks goals were to finish attaching the pedal pusher components, install the arduino and batteries, and to edit the code for the arduino. After this week the final goal is to have the Power Wheel driving around on its own with minimal interaction with the human operator.

Pedal Pusher Assembly

The construction of the pedal pusher assembly was finished last week, when the mounting bracket, the last component, was 3D printed using the MakerBot. The mounting bracket was attached using a wood screw to the lower platform of the mounting platform in the Power Wheel. The mounting bracket was not strong enough to handle the forces exerted on it by the pedal piston and the movements of the Power Wheel as it drove around, it bracket broke at the tab and need to reattached using hot glue. The mounting bracket was 3D printed with 30% fill and that was not sufficient enough for the needs of this project, future groups should reprint the part, with 50% or more fill to increase the structural integrity of the part.

When the screw motor was about to be attached to the lower platform, it was too low and did not fit properly with the mounting bracket. To resolve the issue a 1/4" plywood shim was cut and placed underneath the screw motor to elevate it to the proper height. The wooden shim was attached using hot glue.

The screw motor itself was attached with a metal bracket. The metal bracket was made from a bent metal sheet. The bent bracet was attached around the body of the screw motor with wood screws.

Attaching Arduino and Batteries

The batteries and arduino needed to be installed in the Power Wheel to the mounting platform. Since this project will be active for many more semesters, the components were attached using electrical tape. This was done to allow the parts to be moved to different locations if needed, as other groups work on the project. The parts are attached and secure, this is to prevent any damage, malfunction, or disconnection of parts from the Power Wheel. Future groups, as other components are added, can change the location of the existing components to allow room.

Arduino Code

The Power Wheel needed to drive in a predetermined pattern, to accomplish this it first need to make a turn. To make a turn the Power Wheel needed to do a sequence of actions executed by the arduino starting from a stopped and neutral position:
 * 1) Turn the steering wheel all the way to the left, by extending the miniature linear actuator.
 * 2) Depress the gas pedal with the pedal piston, by turning the screw motor for 1.35 seconds.
 * 3) Keep depressing the gas pedal with the pedal piston for 5 seconds.
 * 4) Remove the pedal piston from gas pedal, by reversing the screw motor for 1.35 seconds.

This was a success and the Power Wheel was able to, from a stop, make a turn to the left, drive through the turn, and then come to a stop.adchived

The initial turn was 130°, it was 40° more than what the goal for the turn was, to resolve that the code for how long to depress the gas pedal was changed by 0.5 second increments till the correct turning radius was archived.

The time of 3.5 seconds was used for the turning code. This allowed the enough time for the Power Wheel to make a 90° turn.

Test Run

Test 1

Test 2

Test 3