27
Which actuators are suitable for your application depends very much on what kind of robot arm you want to build. Once you have decided on what kind of arm you want you can decide on a suitable actuator for each axis.
The Arm
Assuming from your description that a gantry robot wouldn't be viable, then depending on your specific application, you may want to ...
19
The Android Accessory Development Kit (ADK) should do everything you need.
It's an Arduino board that is specifically designed to interact with Android. You can connect the two over Bluetooth or USB (or WiFi/Ethernet, I think).
Since the whole architecture is open, you can use each part for what it's best at. You write the Android code to get data from the ...
13
When you're choosing actuators, it's instructive to start by calculating how much power you need at the end effector. When you say 'not too slow' you should have some idea what this means, especially under different load conditions.
For example, you might say: 6kg at 0.2m/s and 0kg at 0.5m/s
Now add in the estimated weight of the arm: 10kg at 0.2m/s and ...
11
Another option is the IOIO-OTG board:
The Sparkfun product description describes its functionality:
It features a PIC microcontroller which acts like a bridge that connects an app on your PC or Android device to low-level peripherals like GPIO, PWM, ADC, I2C, SPI, and UART. An app-level library helps you write control code for these low level peripherals ...
10
It would be easier to give an answer if we knew what you want to use this for. That would give an idea of your requirements in terms of speed, cost, and space requirements.
As Rocketmagnet has pointed out, you can use a belt drive, or long pitch screw. And you have already mentioned a rack and pinion system. These are all involve a conventional (DC) motor ...
7
As others have said in comments, a screw is probably your best bet. It's mechanically pretty simple to set up, and could be made to look fairly tidy, which is always nice in a home.
But the main problem, as always is going to be doing this on the cheap. The cost of the parts soon adds up. Even if your motors are only $15, you still need to buy the lead ...
7
I don't know if this qualifies as a rack & pinion, or rope wound round a stick, but a simple belt drive actuator is very fast and smooth. I'm using one for a SMD pick and place machine where I need very good speed and smoothness of movement.
Linear actuators based on screws don't need to be slow at all, it just depends on the pitch of the screw you use. ...
6
The main problem as I see it isn't really interfacing with actuators-- if you have a good way to wirelessly transfer digital (even better would be analog, or a channel good enough to do PWM) signals, you can just interface that with a motor driver chip (e.g. L293D) and be good to go. For servos, you need good response time so that you can handle the pulses. ...
6
In short, what you are trying to do is well beyond the capabilities of top robotics research labs.
That said, here is a short list of general areas you need to look into:
Robotic arm dynamics (to swing the racket)
Vision processing to track the shuttle
Shuttle dynamics to predict shuttle path (this is not well studying so you would most likely have to ...
6
Actuators that use a worm gear can't generally be back-driven; these are the same gearing mechanisms that let you twist a guitar string to tune it without the tension being able to back-drive (and thus un-tune) the tuning mechanism.
Worm gears are nice in that they offer generally pretty huge reductions in speed, with a huge increase in torque. This leads ...
5
Yes, the lack of GPIO pins on smartphones is a shame. If you already have ROS running on the robot you could use this app on an Android phone to get access to the sensor suite on the phone.
5
Many parts of the actuation system create noise. One important noise generator is the gear train between the motor and the effector. All of those toothed wheels rattle slightly against each other, each contributing slightly to the orchestra of noise. This is one of the reasons behind the development of Maxon's Koaxdrive gear, which is targeted at low noise ...
5
With a series of planetary gear sets aligned axially, one can gear down by high ratios. For example, the picture below (a wikipedia commons image used in the planetary gear article) shows a 2.5-cm gearset with ratio -5/352, about 1:70. Stacking three of these would give a ratio of about 1:343000. Some torque and power would be lost to friction, and ...
5
Mobile platform: An electro-mechanical linear actuator can be a good choice for light weight actuator which can be mounted on mobile platform.
Battery powered: An electro-mechanical linear actuator is good choice over servo motors, as linear actuators draw power only when it is moving, and it does not need power to hold its position.
5-6 DoF: It might be ...
5
When selecting an actuator, you need to consider not just the force but also the power.
Power = force x speed
The faster you need to lift the lever, the more power you'll need. Companies like Maxon provide detailed graphs showing exactly how much torque you can expect at various speeds for their motors. Other companies may just state the motor's wattage.
...
5
To answer your questions about the motors/gearing:
To lift 5Kg at 1 metre distance - the "shoulder" torque needs to be 500 Kg.cm or about 5000 N.cm.
This is far above the torque of most model servos, so forget them; robots of this sort of performance generally use a specialist motor, much more than 12V and a purpose built gearing arrangement that probably ...
5
Series elastic actuators tend to have more stable force control because the spring filters out the high-frequency motion of the mechanism. A low frequency in the system dynamics means that you can use slower control techniques, which is important when using digital controllers with naive control implementations, and sensors with significant abbe error and ...
4
Well, being the manipulator removable, so you can attach other thing to the valve shaft, you have so much options.
Mechanical coupling
You could use a coupled rotary actuator to the shaft by the means of a shaft coupler. There's many types, this is a simple one, but you probably would not get the actuator axle full aligned with the valve shaft, so a ...
4
The device you are looking for is a "pan-tilt" unit. They are typically used for pointing security cameras. If you find a "PTZ", i.e. pan-tilt-zoom security camera used, you could butcher it an just use the Pan/Tilt part.
4
Many recent Android devices, such as the Nexus 7, support USB On The Go (OTG) which is a fancy way of saying that 'USB Host Mode' is supported. In these cases, with the right cable which can be had for less than $1, any compatible USB device can be used. You don't need a specialty version of the Arduino that has hardware for USB Host mode.
I've ...
4
There is the motor with its mechanical balancing, and its bearings, and all associated rotary parts, with their respective vibrations, adding up. If a brushed DC motor is used, the brushes have an inherent commutation "whirring".
Also friction noise of all moving parts, though this last is much damped as a side-effect of lubricants used, hence usually not a ...
4
When there is miscommunications between the microcontroller and a chip, assuming the electronics are not damaged, there could be a couple of things that can go wrong. Of course, further diagnosis is required. Typical things that could go wrong are (generally, not just in your particular case):
Connections: Is the chip connected to the correct power supply? ...
4
Regarding point 1, yes you are understanding the problem correctly.
Regarding points 1 and 2, I believe what you are looking for is the Nyquist-Shannon sampling theory. This theory says that your sampling frequency should be greater than 2x your "highest frequency of interest". This is to prevent aliasing, where you can incorrectly measure a high-frequency ...
4
The Boston Dynamics’ Atlas robot doesn't actually use servo motors. It uses electrically-powered hydraulic actuation.
I saw a presentation by Boston Dynamics' Marc Raibert where (if I remember correctly) he said they used to use Moog actuators designed for the aerospace industry, but that they were now using a motor that they build in-house that is ...
3
Whilst the two answers in place focus on mechanical noise (which is what I think you are asking about) there is also, of course, electrical noise which manifests itself as Electro-Magnetic Interference (EMI or also known as EMC)
Anything that contains a motor is likely to generate a level of EMI... normally a small level that you don't notice it, but with ...
3
This design is definitely plausible, but there are some problems I can see.
The maximum length is defined by the force the magnets can lift, since the ones lowest in the stack won't push the other ones up after some amount of them.
The magnets will want to get as far from the force as possible, so they will most definitely not go straight up. This calls for ...
3
First, let's consider what actuator you need to physically push a button. One straight forward solution is to use a RC-Servo motor. An RC-Servo motor is a high torque (DC motor with gearbox) actuator which can be instructed to rotate at a specific angle. It is controlled through a PWM signal. So you need to figure out the duty cycle of the PWM signal to do ...
3
One approach would be to use and Arduino with an ethernet shield. There are plenty of examples online for both of these devices. From there you would just need to create a GUI and the build your robot to push the button.
3
There are two more factors to consider: Complexity and cost.
Industrial robotic arm like that
industrial robotic arm http://halcyondrives.com/images/robotic_arm.png
Image from http://halcyondrives.com
normally use torque from the gearbox to direct drive the joint, now think about the torque the gear reduction should support and the size/weight it will be? ...
3
I always add 100-120% overhead (normally this just means the next bigger unit than exactly what I need) but also this comes with experience, a motor that can just barely lift your load will do so very slowly.
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