Hi everyone
I am doing a project,Haptic Robotic Arm,in which a human user wears a glove and the series of movements made by him are imitated by a robotic arm.Could you guys suggest any sensors to sense the motion of the hand.
Initially I am planning to use this robotic arm .
The robot arm can mimic wrist and elbow movements, as well as finger movements. That's going to be a pretty large glove...
A haptic device provides feedback to the user (the glove wearer), so that, for instance, the user can sense how heavy the object being picked up is, and squeeze harder for heavy objects than for light objects.
Presuming you figure out how to sense the position of the fingers, wrist, and elbow, and you figure out how to map those movements to the robot arm, how will you provide the force feedback?
I am not using any feedback cause it will make the project more complex.Can I use an acceleration sensor to sense the movement of the hand ?
I tried that once...
http://www.arduino.cc/cgi-bin/yabb2/YaBB.pl?num=1248289666
Detected tilt... very "iffy" if you know what I mean... I always planned to add some bend sensors to the index and thumb fingers on the glove, but never got around to it. Either way, the thing wasn't magnificent (also, I couldn't figure out how to keep the x tilt and y tilt separate - I recall it had something to do with Euler angles - Wikipedia but never figured it out.
I'd go for flex sensors for the fingers/thumb (and maybe wrist). Have a look here for an example: http://itp.nyu.edu/physcomp/Labs/Servo
Andrew
I am not using any feedback cause it will make the project more complex.
Then it isn't going to be a Haptic Robotic Arm, and you're topic title is misleading.
Thanks for your replies guys.I am planning to use a set of LEDs on the glove to indicate the movement of the robotic arm to the user.Now can it be considered "haptic" cause it has a feedback to the user ? Also suggest any sensor for the movement of the hand please ........................ :-?
Now can it be considered "haptic" cause it has a feedback to the user ?
No. Why?
Try this on for size...found it yesterday. There's also a youtube video on the Videos page that shows the arm in motion side by side with the controller.
If you really wanted to do this "right", you would use a magnetic or optical 3D tracker system and RK (reverse kinematics) the endpoint of motion (the hand) to the arm.
I understand this this is likely waaay out of your budget and/or experience.
Building the glove is actually the easy part (ok, putting the robot together and hooking it to the Arduino is arguably easier); you can utilize resistive bend sensors (which you could purchase or make), or you can utilize a form of optical bend sensing using either optical fibers or aquarium tubing as the element being bent to change the level of light on a sensor.
A possibility for the 3D tracking aspect on the cheap (and the glove) would be to hack a PowerGlove to interface it to an Arduino, and use the Arduino to interpret/filter the values, then pass them on to a second Arduino to control the robot arm (hmm - could you implement an efficient but simple RK algorithm on an Arduino?).
For haptic feedback, there exist really tiny cellphone vibrator motors (less then 1 cm in diameter, I think) that you could put on the fingertips. If you wanted true haptics, you could put aquarium tubing along the back of the knuckles (or front of the fingers, whichever) that you could apply pressure to using a compressor, and valves controlled by another Arduino (how many are we up to here, 3?), to apply varying levels of pressure to correspond to resistance...
What would actually be more useful, more intuitive (from a user standpoint), and easier to learn and control the robot with, though, would be a jointed arm "pointer" interface. The pointer arm would have identical joints to the robot arm, with potentiometers at the joints to determine the angle of the joints. You would translate these into joint angles for the robot. On the last arm of the pointer (which could look something like a pencil/stylus), you could have one or two switches to control the open/close function of the arm, as well as the light (turning it on or off). A vibration motor in the base could serve as some haptic feedback.
Something to consider about that robot - I have yet to see anybody being successful with interfacing a feedback mechanism for the motors on it - they aren't servos, they are regular gear motors, and there isn't much/any room in the gearbox for sensors, encoders, or potentiometers. I think if you can solve that, you might make a ton of people happy, myself included (I purchased one of these arms, but I have yet to remove it from the package - though I intend to use it in an Arduino related project in the future).
Good luck.
Guys, I completed my project to a extent without the feedback part(so it is not Haptic). I am able to control the robotic arm with the glove. See this video of my project
I completed till this on April 2010. Am still searching for ideas to implement the Haptic part. Please see the video and give your suggestions, ideas and comments.
Pretty cool!
You should work on the response time though.
Actually, I have programmed in such a way that the robotic are moves only after the movement of the human arm is stopped. I have done this way to ensure there is no unnecessary movement. For instance, if I moved my hand rapidly and stop the position of my hand at the same position as in the beginning, the Robotic arm would not move at all. It waits for the variation in value caused due to the hand movement to stabilize.