Final Presentation_Capstone Project
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The UC Berkeley Capstone Project aims to design a 5-axis optical image stabilizer for cellphone cameras. The team is designing the overall structure, voice coil motors using magnets and coils, and spring plates. They have considered different actuator options and selected voice coil motors based on their performance in smartphones. Through testing various magnet-coil placements and spring designs, the team developed a final design and working prototype that can compensate for hand shaking in 5 degrees of freedom using an Arduino, gyro sensor, and servo control.
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Final Presentation_Capstone Project
- 1. UC Berkeley Capstone Project Optical Image Stabilizer for Cellphone Camera
- 2. Team and Advisors Jili Liu, Product Design, ME Ye Yuan, Product Design, ME Zheren Wu, Control System Design, ME Faculty Advisor: Prof. Liwei Lin, Department of Mechanical Engineering Industry Advisor: Dr. C.H Lin, Industrial Technology Research Institute
- 3. How does OIS work? Take Photos :) Blurry Photos caused by hand shaking :( OIS on, photo blurring reduced :)
- 4. What we are working on ... We are designing: ● Five-axes OIS ● Overall Structure ● Voice Coil Motor (Magnets and Coil) ● Spring Plates
- 5. Five-axes OIS Auto-focus 1 axis Auto-focus 2 axes Shift OIS 2 axes Tilt OIS Five-axes !
- 6. Actuator Selection Stepper Motor External camera gimbal
- 7. Actuator Selection Voice Coil Motor iPhone 6+ Camera Module
- 8. ● Disassemble an iPhone 6+ camera to see how parts are actually connected ● Get an impression of the actual dimension of mechanical structure ● Figure out the magnet - coil placement iPhone 6+ camera breakdown
- 9. Final Design ➢ Desirable Magnet-Coil placement ➢ Delicate spring design ● Housing ● Suspension ● Actuator
- 10. Voice Coil Motor Design #1 VCM Design #1
- 11. VCM Electromagnetic Analysis Force Performance Camera Lens AF force in Z (mN) OIS force in X (mN) +8.8 +11.1 X Z * I: Coil current, 9.4 A * B: Magnetic flux * L: Length of coil * Force: F=I×B×L
- 12. VCM Design # 2 Voice Coil Motor Design #2
- 13. VCM Electromagnetic Analysis * Coil Current: 9.4 A Force Performance AF force in Z (mN) OIS force in X (mN) +16.3 +9.9 Magnetic flux cancellation Magnetic flux strengthened
- 14. Spring Design Iterations Spring Design 1 Spring Design 2
- 15. Spring Validation - Static Analysis Spring 1 Spring 2 Spring 3 Spring 4 AF Z-axis Z-axis Z-axis Z-axis OIS-Trans X-axis Y-axis X-axis Y-axis OIS-Tilt Z-axis - Z-axis Autofocus, 0.2mm OIS - Trans, 0.1mm OIS - Tilt, 0.5 degree Work under VCM Design#1
- 16. Prototype & Demo (a) Scale-up camera housing (b) SBFHD01M prototyping camera (c) Arduino set up and servo control (d) InvenSense MPU 6050 gyro Prototype & Demo
- 17. Future Work ● Optics (lens) ● Image Sensor (CMOS) ● Camera module system level design & analysis ● Manufacturing process
- 18. Degrees of Freedom • Auto-focus in Z-axis • Shift movement in X-axis • Shift movement in Y-axis • Tilt movement around X-axis • Tilt movement around Y-axis
- 19. Appendix
- 20. Actuator Approach A: Comb Drive CCM Size 6 mm (Diameter) X 1 mm X 3 pieces Payloads 4 mg Displacement /Stroke 0.1 mm Response time at least 2 times faster than VCM Voltage 17 V ~ 31.5 V Shock (Drop Test) > 10000g shock Pros -Fast response -Energy efficient -If designed correctly, cheaper -Smaller Cons - Hard to manufacture - Delicate design - High voltage
- 21. • Delicate structure design leads to low energy consumption • Much more accurate compensation • Requires precise machining and high cost for large volume application • Problems in manufacturability and assembly in small volume Actuator Approach B: Piezoelectric Actuator
- 22. Approach D: Shape Memory Alloy OIS dimensions (L x W x H) 9.5 mm x 9.5 mm x 3.8 mm SMA wire thickness 25 um Operating voltage/current 120 mA Response time 33 milliseconds Pros 1. no position sensors or magnets 2. high force 3. compact size Cons 1. slow cooling 2. compensation error due to material properties Translational move/tilt tilt Moving part Camera unit
- 23. iPhone 6+ Camera Module CAD
- 24. Coil Size & Current Limit Calculation (½)
- 25. Coil Size & Current Limit Calculation (2/2)
- 26. VCM Design 1 Dimensions (½)
- 27. VCM Design 1 Dimensions (2/2)
- 29. Design Iterations I Idea: ● Move the image sensor, fix the lens ● Special designed spring to enable 5 axis movement Pros Cons i) simple structure ii) shrunken size i) difficulties in moving image sensor ii) complex control design
- 30. Design Iterations II Idea: ● Three-frame structure to enable 5-axis movement and AF ● Ball joint and recovery spring structure for shifting the lens Pros Cons i) fix the image sensor ii) easy in control i) difficulties in utilizing ball joint in this size ii) relatively large overall size
- 31. Design Iterations III Idea: ● Two frame structure to enable 5-axis movement and AF ● Slide and spring holder utilized to shift the lens Pros Cons i) fix the image sensor ii) easy in control iii) remove redundant material i) complicated mechanical structure ii)multifunctional spring, no failsafe
Editor's Notes
- Alex & Vivek: Not very easy to understand for audience. Put this page and next page together in one single slide, highlight the movement of lens
- Vivek: It looks that there is already certain product in the market, why your design necessary
- Vivek: It looks that there is already certain product in the market, why your design necessary
- Unlike large gimbal, the external camera stabilizer which could use servos or DC motors. The camera we are dealing with has to fit in a smartphone in your pocket, which is smaller than a penny. We can’t fit a giant actuator in a smartphone. so we have to go for small actuators. Voice coil motor, also known as VCM is commonly used in the cellphone camera world due to its simpleness and high reliability. So when the coil is electrified in the magnetic field, physics tell us a Lorenz force will apply on the coil proportional to the current. What we need to do is carefully put the coil and magnet in the perfect position to ensure we get the desirable driving force. With this kept in mind, we begin our design process.
- Unlike large gimbal, the external camera stabilizer which could use servos or DC motors. The camera we are dealing with has to fit in a smartphone in your pocket, which is smaller than a penny. We can’t fit a giant actuator in a smartphone. so we have to go for small actuators. Voice coil motor, also known as VCM is commonly used in the cellphone camera world due to its simpleness and high reliability. So when the coil is electrified in the magnetic field, physics tell us a Lorenz force will apply on the coil proportional to the current. What we need to do is carefully put the coil and magnet in the perfect position to ensure we get the desirable driving force. With this kept in mind, we begin our design process.
- Vivek: The iPhone 6 disassembly video is fabulous:) Before we actually design anything, we disassembled an iphone 6+ camera to get a sense how things are orginized in the current product as well as a visual impression of the actual size. This is a small video we shot during the breakdown process. It was quite fun.
- This is our final design. 4 sets of vertical spring are attached to the walls of the housing. Those springs hold the lens barrel and enable it to move in the open space in the housing. And the white part in the left bottom corner of the first picture is the magnet. Remember the VCM we mentioned earlier? There should be a driving force to actually move the lens. And the magnet here is to provide the desired magnetic field. As you can see, the success of this design highly depends on the magnet- coil placement and the spring design. So further simulations were delivered to optimize and validate the design, those work will be demonstrated by Zheren and Jili.
- Alex: When audiences see two designs, the first question is “ what is the difference between the two designs?”
- Alex: The Maxwell picture is very cool. What is the relationship between the picture and your table？ Why do we need to know the numbers in the table?
- Alex: When audiences see two designs, the first question is “ what is the difference between the two designs?”
- Alex: The Maxwell picture is very cool. What is the relationship between the picture and your table？ Why do we need to know the numbers in the table?
- Alex: The table doesn’t make sense, why do we need to know the spring constant?