mr_byte31
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« on: November 19, 2018, 09:34:02 09:34 » |
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I am making a control system for a very old Crane. I build the full system using PLC. The only sensor I couldn't find easily was the angle sensor. The crane use "Boom angle sensor". I need to order it from Alibaba. Its price exceeds $100. I would like to find a low cost solution. I tried to substitute this sensor with a normal variable resistor and I added a small weight to it. it looks like a pendulum. The weight is always going down due to gravity and when the crane go up or down, the angle of the resistance change. The solution works for some days and then the resistor is damaged because of the vibration in the machine ! The error in reading the angle shall not exceed +1 or -1 degree (requirement) I thought to use MPU5060 as angle sensor. I watched some videos on youtube but it seems not very sensitive and I am not sure about how much it needs calibration. I found a program on my Asus phone that make the phone acts as angle sensor but I was confident that this solution is not very reliable. I was asking if someone know a more convenient solution.
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« Last Edit: November 19, 2018, 09:47:16 09:47 by mr_byte31 »
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pickit2
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« Reply #1 on: November 19, 2018, 10:06:51 10:06 » |
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look on e-bay for level box. I'm sure you could easy convert it to an input device.
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leptro
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« Reply #2 on: November 19, 2018, 10:43:18 10:43 » |
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Hello, Have a look on sensitec AL798AMA-AE available from RS.
They have analog output.. so will need some computing routine to use it.
I have never used them.
Regards.
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hosmis
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« Reply #3 on: November 19, 2018, 12:08:31 12:08 » |
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mr_byte31
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« Reply #4 on: November 19, 2018, 01:19:16 13:19 » |
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look on e-bay for level box. I'm sure you could easy convert it to an input device.
It is nice idea but no interface to the device. I think this is accelerometer , I think MPU5060 still have such thing but this is not reliable ! Hello, Have a look on sensitec AL798AMA-AE available from RS.
They have analog output.. so will need some computing routine to use it.
I have never used them.
Regards.
I will check about this.
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b555b
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« Reply #5 on: November 19, 2018, 03:42:20 15:42 » |
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Maybe you can use a magnetic rotary position sensor (for exemple from AMS https://ams.com/angle-position-on-axis ). Either by placing a magnet and the sensor on the rotation point of the boom, or by replacing your variable resistor pendulum by a fixed sensor on the boom in front of a magnet whose rotation is controlled by the pendulum.
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« Last Edit: November 19, 2018, 05:13:28 17:13 by b555b »
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hosmis
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« Reply #6 on: November 19, 2018, 05:16:06 17:16 » |
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SCA610-C28H1A no accelerometer , this is inclinometer very stable chip vibration resistant https://www.mouser.com.tr/datasheet/2/281/s47e-522718.pdfanalog + digital output ±30°, ±0.5 g ±90°, ±1 g
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fpgaguy
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« Reply #7 on: November 19, 2018, 05:50:05 17:50 » |
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« Last Edit: November 19, 2018, 05:59:30 17:59 by fpgaguy »
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mr_byte31
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« Reply #8 on: November 20, 2018, 05:31:01 17:31 » |
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Sorry guys, I still didn't get it.
you provide me with sensors for detecting how far is the object. I still don't know what to do with such thing.
The previous sensor was placed as seen in attached figure(check red arrow).
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Wizpic
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« Reply #10 on: November 20, 2018, 08:26:24 20:26 » |
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When you think, "I can't do anymore. I need a break," that is the time to challenge yourself to keep going another five minutes. Those who persevere for even an extra five minutes will win in life..
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pickit2
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« Reply #11 on: November 20, 2018, 10:12:51 22:12 » |
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MEMSIC accelerometers and tilt sensors the Level Box has 3 main ic's 1 micro 2 lcd driver 3 tilt ic try buying the tilt ic cheaper than a Levelbox Mr Byte you always want a full solution, we try to guide you. Not do the job for you, you have to do that.
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« Last Edit: November 20, 2018, 10:25:11 22:25 by pickit2 »
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Wizpic
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« Reply #12 on: November 20, 2018, 10:31:49 22:31 » |
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Yeah I have been looking at those too, this project interests me and sounds an interesting project to be working on, reminds me of the project I was involved in a few years back when I built and designed a bespoke lift for a Wurlitzer to lift it out of the ground and automatically stop once night was reached, had to follow strict guidelines to meet the CE requirements plus it had to be really smooth and run from the mains using a dc motor and controller.
How accurate do you need the angle measurements need to be? The only reason I ask could you use a few limit switches where you could lay them out say 10;30,50,70,90 degrees the only draw back to that is you would not know where it was in between the limit switches. Like others mentioned accelerometer chip may be the way to go. I may have a solution we use a few different types of angle sensors on our equipment but it all depends on your max angle you need to detect, I think these give a 0-5v ouput and know for a fact they give very stable ouput as they are used on scissors and booms machines, I could see about powering one up and compare them against max angle you require and see if that helps and I can let you know the make and you may be able to get one
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« Last Edit: November 20, 2018, 10:48:40 22:48 by Wizpic »
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When you think, "I can't do anymore. I need a break," that is the time to challenge yourself to keep going another five minutes. Those who persevere for even an extra five minutes will win in life..
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mr_byte31
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« Reply #14 on: November 22, 2018, 09:12:49 09:12 » |
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MEMSIC accelerometers and tilt sensors the Level Box has 3 main ic's 1 micro 2 lcd driver 3 tilt ic try buying the tilt ic cheaper than a Levelbox Mr Byte you always want a full solution, we try to guide you. Not do the job for you, you have to do that. Not really but I am searching for an answer that I can understand and implement. I mentioned that I already looked for MPU5060. doesn't it have the same concept for ICs mentioned in the thread? Maybe some of them. I am just afraid of calibration issues and precision ! Posted on: November 22, 2018, 03:55:14 03:55 - Automerged
Yeah I have been looking at those too, this project interests me and sounds an interesting project to be working on, reminds me of the project I was involved in a few years back when I built and designed a bespoke lift for a Wurlitzer to lift it out of the ground and automatically stop once night was reached, had to follow strict guidelines to meet the CE requirements plus it had to be really smooth and run from the mains using a dc motor and controller.
How accurate do you need the angle measurements need to be? The only reason I ask could you use a few limit switches where you could lay them out say 10;30,50,70,90 degrees the only draw back to that is you would not know where it was in between the limit switches. Like others mentioned accelerometer chip may be the way to go. I may have a solution we use a few different types of angle sensors on our equipment but it all depends on your max angle you need to detect, I think these give a 0-5v ouput and know for a fact they give very stable ouput as they are used on scissors and booms machines, I could see about powering one up and compare them against max angle you require and see if that helps and I can let you know the make and you may be able to get one
max error shall be in range of +1 or -1 degree this is the challenge for me ! Posted on: November 22, 2018, 03:56:45 03:56 - Automerged
It is not clear how I use this IC on the crane ? I know the concept used in the IC. Mainly it shall be connected inside a motor or stuff like this. Posted on: November 22, 2018, 03:58:45 03:58 - Automerged
The hall effect sensors will not be a suitable solution for my project. Those sensors depend on a moving object that cause change in the magnetic field. if the sensor is closed and the angle was changed due to a certain reason, the sensor will not be able to tell what is the true angle. the boom angle sensor will be able to adapt to any change even if the machine is switched off since the weight is always pointing to the ground ( gravity direction)
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b555b
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« Reply #16 on: November 22, 2018, 09:27:28 09:27 » |
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Posted on: November 22, 2018, 03:58:45 03:58 - Automerged
The hall effect sensors will not be a suitable solution for my project. Those sensors depend on a moving object that cause change in the magnetic field. if the sensor is closed and the angle was changed due to a certain reason, the sensor will not be able to tell what is the true angle. the boom angle sensor will be able to adapt to any change even if the machine is switched off since the weight is always pointing to the ground ( gravity direction)
Have you looked at the sensors of post #5. These are not simple hall sensors, but a combination of several hall sensors with some internal processing that is able to give you the absolute orientation (angle) of a magnet relative to the sensor with up-to 14-bit accuracy. Even if you turn off the system, rotate the magnet, turn the system back on, the sensor will gives you the new angle of the magnet. Replace the potentiometer of your original experiment with such a sensor fixed to the boom and a magnet at the rotational axis of your pendulum.
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hosmis
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« Reply #17 on: November 22, 2018, 11:39:32 11:39 » |
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MPU5060 MPU9055 MMA8451 ADXL345 etc... not suitable for professional work at least not suitable for crane maybe BNO055 not available on vibrating device you cannot compensate
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mr_byte31
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« Reply #18 on: November 22, 2018, 04:02:03 16:02 » |
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Have you looked at the sensors of post #5. These are not simple hall sensors, but a combination of several hall sensors with some internal processing that is able to give you the absolute orientation (angle) of a magnet relative to the sensor with up-to 14-bit accuracy. Even if you turn off the system, rotate the magnet, turn the system back on, the sensor will gives you the new angle of the magnet. Replace the potentiometer of your original experiment with such a sensor fixed to the boom and a magnet at the rotational axis of your pendulum.
Many thanks for the idea. This is something to consider but it will not be on the first list. sorry to say that. to perfectly add a magnet and a sensor on an old crane is not easy task but it is feasible. I am afraid that the magnetic pattern will have much noise due to the different metal parts of the machine. The challenge is that those machines are most of the time dirty, vibrate and several maintenance can make things vary. The boom angle sensor seems like the perfect solution since it doesn't matter with all variations on the machine ! I am trying to see a possible solution using variable resistance and a load ! Posted on: November 22, 2018, 11:00:50 11:00 - Automerged
MPU5060 is not a good solution for industrial products. The error is high
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pickit2
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« Reply #19 on: November 22, 2018, 08:36:17 20:36 » |
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Did you read the data sheets, you can get rid of errors, your not going 100mph in moving the jib. well the one by MEMSic MX2500E is in their list of devices for crane boom arms. and is used in the Levelbox. you don't get it. I said try the levelbox as you only need to connect two wires and ground to break out into the real world. but then you just skipped what was said. back in the day cranes had a plumb bob, and the person who operated it knew what they were doing.
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hosmis
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« Reply #20 on: November 22, 2018, 08:50:59 20:50 » |
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« Reply #22 on: November 24, 2018, 10:47:13 22:47 » |
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As you are dealing with a mechanical device you should also consider the possibility of losing sensor power while the boom is in an arbitrary position. By using incremental type encoders you should not trust the last known position in order to start calculating a boom new position, since the mechanism could have moved while the power to the sensor was off. In that case it is imperative to have an absolute type sensor or a power on routine to move the boom into a limit sensor with a known position (home position).
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CocaCola
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« Reply #23 on: November 25, 2018, 04:47:18 04:47 » |
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or a power on routine to move the boom into a limit sensor with a known position (home position). But, this can't be automatic since you are outside a controlled environment... The last thing you want is to be hovering a load or even an empty boom having a sensor power glitch or even just turn the machine on and all the sudden have the boom moving without any user control or consent... Best to have a calibrate on power option, but only with operators consent to initiate the calibration... Honestly at the end of the day, if there is a $100 over the counter device designed for just this application, it's really silly IMO to try to re-invent and take on the liability of an unproven design, to save literally a few dollars...
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hosmis
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« Reply #24 on: November 25, 2018, 07:42:59 07:42 » |
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Inclinometers (SCA series ) does not need calibration. Power on or off, always works according to gravity.
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