Tactile sensors for Hubo robot

This is a draft of the installation instructions. Please send us an email at moc.elitkkat|maet#moc.elitkkat|maet if something requires clarification.

Kit components

4x Finger boards (plus 1 spare)
1x Palm board
1x Communication board

Installation of Finger Boards

The finger boards shape was designed such that it would match the shape of the fingertip.
The wire should go on the back of the finger and connect to the communication board.

Attachment of the sensor

The sensors are provided with double sided tape.

  • Clean the fingertip place (e.g. wipe with alcohol)
  • Peel the white protection off
  • Place the sensor into its position on the finger tip, and press firmly to secure.
  • We would recommend using superglue to attach the sides of the rubber to the fingertip for increased protection.

Attachment of the wire to the finger

  • The wire from the sensor should be placed on the back of the finger.
  • We envision the wire being wrapped tightly around the fingertip and held in place against the back of the fingertip, pointing down the back of the finger so it does not catch. It is highly recommended to use tape or adhesive wire holders. They can be attached to the finger at the place as indicated in the figure below. An example of the adhesive wire holder is here

Connecting the wire

  • Wire connection has a polarity which is important. Please see the section Communication board.
takktile_hubo_installation.jpg

Installation of Palm Board

Attachment of the sensor

The palm board was supplied with double sided tape for attachment.

  • Clean the palm (e.g. wipe with alcohol)
  • Peel the white protection off
  • Place the sensor into its position on the palm, and press firmly to secure.

Alternative attachment

  • The board can be also attached using two M2 screws as indicated on the figure below.
takktile_hubo_palm_board.jpg

Communication board

The communication board is a custom I2C bridge between sensors and USB. The board is shown in the figure below.

takktile_hubo_communication_board.jpg

Connecting the sensors

Sensor connectors have polarity!. The white marking on the sensor connector should be towards the back side of the communication board. The example is shown in the figure below.

When they are plugged in, the LEDs in each finger should turn on. If they do not, you probably have it incorrectly inserted.

After the sensors are plugged in, plug the host board into the main computer. The LED should blink once, then turn on after a few seconds. If it does not, it is usually a sign that the I2C lines are somehow scrambled due to a damaged wire or conflicting finger addresses on the same bus.

takktile_hubo_communication_board_connection.jpg

Attaching the board

The board was designed to be attached directly to the side of the hand using two-sided tape. To make sure that wire length is sufficient:

  1. Connect all the sensors to the board
  2. Close the hand fingers
  3. Attach the board to the hand

Software and Interface

The default operating system for trying sensors is Ubuntu.

Basics

Please start by going through TakkFast tutorial here

ROS (Robotic Operating System)

After finishing the Basics section, lets explore the TakkTile ROS package.
Please read and install TakkTile ROS from here

Sensor Indexing

Each board has a dedicated address, and as such each sensor has a dedicated address.
Connecting boards with same address will result in an conflict.

Board Name Sensors Available Notes
Palm Board [0,1,2,3] [5,6,7,8] [10,11,12,13]
Finger board 3 [15,16,17,18]
Finger board 4 [20,21,22,23]
Finger board 5 [25,26,27,28]
Finger board 6 [30,31,32,33]
Finger board 7 [35,36,37,38] This is a spare board, in case of any difficulty installing, etc.

To check which sensors are active subscribe to the sensor_info topic under ROS

rostopic echo /takktile_ros/sensor_info

To plot raw sensor values,

rxplot /takktile_ros/raw/pressure[0]:pressure[1]:pressure[2]:pressure[3]:pressure[4]

note that rxplot takes data location indexes (…2,3,4,5,6…), not sensor_info indices (…2,3,5,6,7…)

To zero thermal drift

rosservice call /takktile_ros/zero

Questions ?

Contact us: here

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