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ULC1001-DRV290XEVM: Technology to detect lens dirt in ULC1001's auto mode

Conor
Mastermind 8820 points
Part Number: ULC1001-DRV290XEVM
Other Parts Discussed in Thread: ULC1001

Hi,

Q1.
The ULC1001 is equipped with technology that automatically detects lens dirt in auto mode. Does this mean that water droplets or contaminants attached to the lens cover cause a change in stray capacitance, causing a change in the voltage/current monitored by the piezo? I would like to know more about the detection algorithm.

Q2.
I would like information on the role of the bracket in the lens cover system.

Q3.
I'm considering driving a 40x50 rectangular lens cover with ULC. Could you please provide information on how to simulations, piezo elements, and other structures?

Thanks,

Conor

  • 0
    TI__Expert 6620 points

    Hi Conor,

    1. The auto mode for the ULC1001 algorithm detects a mass change on the lens, not necessarily what that mass is. This mass detection is done by burst 19 (CONTROL_Burst_MassDetect.), which is calibrated by burst 1 (CONTROL_Burst_Cal_Region_MassDetect). Burst 1 will do a frequency sweep and find the min impendence and note the corresponding frequency. When burst 19 is run, it will do the same frequency sweep and find the min impedance and its corresponding frequency. If the frequency for burst 19 shifted by an amount greater than the mass detect threshold in comparison to the burst 1 frequency, then there is mass detected on the lens. This threshold can be changed to make the system more or less sensitive. When doing auto mode, it is started with burst 19 and then followed with a cleaning sequence that you choose. This could be water, mud, or deice. If mass is detected on the lens by burst 19, it will run the following cleaning bursts and if mass is not detected on the lens by burst 19, it will not run the following cleaning bursts. 

    2. The brackets has a few functions. 1) The bracket is a part of the housing structure to form a watertight seal, which eliminates the need for a gasket. 2) The bracket, together with the lens and piezo, determines the resonant frequency of the ULC system.  3) A bracket with optimized structure and dimensions will help create the proper vibration modes and improve the cleaning performance with less power.   

    3. We currently do not have information for rectangular lens cover systems, only circular lens cover systems using a cylindrical or ring piezo. We do have information on simulating these kind of lens cover systems if you would be interested in that. This could provide a good basis for simulation that you can then adapt to your application requirements. 

    Regards,
    Sydney Northcutt

  • 0 in reply to Sydney Northcutt
    Mastermind 8820 points

    Hi Sydney,

    Your detailed answer is very helpful.

    Comments on A1
    You are using a frequency sweep to monitor changes in the frequency band of minimum impedance! I don't know much about impedance, but does the impedance change depending on the mass of a substance attached to the lens?

    Comments on A3
    Are there any plans to provide simulations for rectangular lens cover systems?
    Also, what should I consider first when creating a lens cover system? I would like to know about the development procedure etc.
    We have verified operation with the lens covers currently provided by EVM and TI, and have deepened our understanding of the GUI.

    Thanks,

    Conor

  • 0 in reply to Conor
    TI__Expert 6620 points

    Hi Conor,

    1: Correct. When there is mass on the lens, the impedance will shift. More mass will cause more of a frequency shift. So if you want to detect small masses on the lens, you can make the mass detect threshold smaller. 

    2: I will let our LCS expert comment on this. Thank you for your patience.

    Regards,
    Sydney Northcutt 

  • 0 in reply to Conor
    TI__Prodigy 320 points

    Hi Conor, 

    We do not have a plan for simulating rectangular lens cover system yet, at least for the next 6 months. To create a new lens cover system, the most important is to match the resonant frequencies of lens and piezo. It is recommended to run FEA simulations to understand how the system vibrates and the goal is to optimize acceleration level across the lens surface by sweeping the dimension parameters of the system. The development procedure would be 1) define your aperture requirement 2) select your lens and piezo material types 3) set up FEA simulations, sweeping the dimensional parameters 4) obtain the optimized design parameters     

    Thanks

    Hailong