Group 38 project

Tennis Ball Collecting Toy Car

Mentor:

   Henry Lee

Members:

   Yuxiang Zhao ( EE & CPE )

   Miao Yu ( CPE )

   Zunwen Li ( CPE )

   Jiajun Hu ( EE )

Poster Link:

 https://docs.google.com/presentation/d/1aJ4YCIUPNLvqophEApKR1I_dFcgQVNXFYaJ8pt0-r0g/edit?usp=sharing

Initial Proposal:

https://drive.google.com/file/d/0B1WqQGDXO49bTmtrRHZhQ3V0ZWFvZ194emU0dlA2aEY0Wl80/view?usp=sharing

Weekly Reports：

​week1-2:

Summary: In this week, we successfully build a car that can move forward, backward.

However, Turn left and turn right are very rigid. We believe more powerful motors can solve

this problems.

We have taken a video about the movement of our car, and we will show you on the

meeting.

Personal Contributions:

Yuxiang Zhao:

1. put wheels on the cars and connect wheels

2. assembly the claw

Miao Yu:

1. code and set up the servo

2. assembly the claw

Zunwen Li:

1. code the movement of the car

Jiajun Hu:

1. improve the ball-detecting code

 

​week3:

Summary:

This week, we changed one of our wheel to universal wheel, so we can turn much more smoothly.

We also mounted our camera on the car, and adjust our code, so the car can move toward tennis balls.

We also have our mechanical claw ready to install.

Next Goal:

Our next challenge is how to detect the distance of the ball, so that the claw can pick up the ball.

Individual Contribution:

(We broke our equipment last week because 1. We forgot to close the window during one of the rainy

day, the microprocessor is damaged, 2. Our base steel plate is conductive and therefore may cause a

short circuit. Therefore, we had some extra work)

Yuxiang Zhao:

1. Find out one of the possible reasons of board damage.

2. Tape metal base plate to prevent short circuit

3. Recode

Miao Yu:

1. Reinstall Raspbarry Pi

2. Install universal wheel

Zunwen Li:

1. Combine ball detecting code and movement code

Jiajun Hu:

1. Mount camera

2. Install mechanical claw, so we can install the claw next time

 

​week4:

Summary: In this week, we successfully pick the tennis ball. Our next goal is making the

procedure faster and more accurate.

Yuxiang Zhao:

1. Adjust camera position, and adjust code and increase the successful rate

2. Create servo turning code

Zunwen Li:

1. Combine servo turning code and moving and detection code

Jiajun Hu:

1. Install the servos

Miao Yu:

1. Improve servo turning code

2. Install the servos

 

​week4-5:

Work done:

1. Hiding wires

2. Install boxes

3. Relocate the control unit and batteries

4. Testing when there are more than one ball

5. Fixing the problem that servo will do several lifts operation for one ball

Problems

1. Servo shows weaker torque than last week

2. Collector will move towards wrong direction when there are more than one

ball, it will change direction constantly.

3. The existing metal pieces we have is not adaptable to our collector.

4. The turning speed of collector is too slow.

Solutions:

1. Since the servo is controlled by pulse with specific pulse width, we use

twenty pulses for one servo operation.

2. We modified the code. It only finds the maximum circle in the graph

before, which will cause problem when two balls are in same y location but

different x location. In this case, the will have same radius and the

collector will change target object constantly. In new code, we saved the

last position of target object, whenever the frame refreshes, it will go

through all the spherical objects in the frame and iterate all of them and

compare the distance to the last position we saved. Then it will choose the

nearest spherical object and rewrite its location to last position, and treat it

as target object. In new code, collector will guaranteed to move towards

the same object instead of changing constantly between objects with same

y location in the frame.

3. We cut the metals into the pieces we need

4. This problem is unsolved because we are trying to figure out whether we

should change the wheel motor. The speed is approaching to its limit.

Since we did it together, all group members contribute same amount of work

 

​week6-7:

Work done:

1. BJT control signal of servo

2. Identify return box

3. Moving the car to return box

Problems

1. Sometimes the car can not do a perfect U-turn

2. Sometimes the car can not identify the return box dot appropriately

Solutions:

1. As we change the control signal of servo to BJT, the turbo of servo

performs much better than the past.

2. We may need another dot to justify the angle of the U-turn to make the car

prefect perpendicular to the return box. The plan is to add another different

color dot in front of the first dot to make the car adjust its angle after the U-

turn.

3. We need to upgrade the code to make a better identification range for the

dot of the return box, which will require a lot of testing.

Since we did it together, all group members contribute same amount of work