I am interested in building a manipulandum. This is a device where a subject grasps a (vertical) handle, and can move the end of device only horizontally (front/back, left/right and combinations of these). The device is used for the subject to make horizontal movements (e.g. move forward 10cm, move to right 10cm, also in diagonal directions). The workspace can be relatively small (say 25 cm by 25 cm).
My plan is something like this:
A device with 3 joints and two links (one joint attached to the table, one joint in the middle (“elbow”) and one joint attached to the handle (to allow rotation of the handle about the vertical axis)
Use ball-bearing hubs (RB-LYN-153) for the 3 joints. Between the hubs will be 6" aluminum tubes (RB-LYN-115), connected to the hubs with the tubing connector hub (RB-LYN-152) and aluminium interconnect (RB-LYN-534).
The handle (a 4.5" aluminium tube, RB-LYN-114) will be attached to the final joint using a connector hub (RB-LYN-111), with a rubber end cap (RB-LYN-126).
The base of the device will be attached to the table via a square hub connector (RB-Mxx-03) and L connectors (RB-LYN-83).
For now, I will measure the movement of the handle using an external motion capture device.
Now for my questions:
- Did I forgot anything?
- Will the device be strong enough to hold itself horizontal or will it bend towards the table? (I tried building a similar contraption using microrax and had this problem).
- How easy will it be to move the handle up and down (which I want to avoid)?
- Is there any easy way to add encoders to the joints to record the angles of the three joints (or at least the first two)?
Thanks in advance for your help.