Project files

fcs4hand2310

Overview

This is a hand that uses four Futaba industrial servos, command-type servos (opens in a new tab).

The link members are intended to be made with a 3D printer. (Please make use of the data in the step folder.)

The hardware_fcs (opens in a new tab) is used to control it with ros2_control.

Launch files and configuration files are provided to control each joint angle with joint_trajectory_controller and to publish the current angles with joint_state_broadcaster.

Operation has been verified on Humble.

Parts List

TTL type

Work Overview

• Replace the connector of each servo module with EHR-4
• Screw the link members to the servo horns
• Attach the servo modules to the link members with double-sided tape
• Screw down the servo module holders at the base
• Make the power cables (hub side, power supply side)
• Wire connections, ID programming, operation check

Precautions

• The section from the USB adapter to the hub is RS-485, so it may be reassuring to add termination resistors at both ends.

RS-485 Type

Compared with the TTL type, RS-485 communication is more reliable, but the amount of work increases. In particular, if you wire the DF11 4-pin connector incorrectly, the consequences could be disastrous and dangerous.

• Change the servo modules to ones with the same external shape but RS-485 type (RS302CD or RS305CR) (opens in a new tab)
• Procure four additional BS3397 RS30x BOTTOM CASE-SHAFT (opens in a new tab) shaft-equipped bottom cases
• Procure one additional set of BS0168 RS2xx/RS3xx FREE HORN SET (opens in a new tab) free horns (5-piece set)
• Change the hubs to a two-piece set of “BA2083 TB-EH31DF-100 or BA2084 TB-EH31DF-200” and “BA2085 TB DF31DF-100” (opens in a new tab)
• Remove the power cable (hub side)
• Make a custom power cable (2 wires, from the power supply side to DF11-4, VCC, GND)
• Make a custom communication conversion cable (3 wires, converting EHR-4 to DF11-4, D+, D-, GND)

| Power cable | Self-made | (as needed) | | | | Tapping screw | (as needed) | (M2 tapping, 10mm) | 34 | | | Double-sided tape | (as needed) | (thin type) | (as needed) | Double-sided tape is used to fix the servo module to the link member | | Link member | (as needed) | (3D print from the files in the step directory) | 1 each | |

Construction Overview

• Replace the bottom case of each servo module with one that has a shaft
  • Mark the wiring
  • Remove the DF11 4-pin housing
  • Replace the bottom case of the servo module
  • Attach the DF11 4-pin housing (take care not to mix up the places where the signal wires are inserted)
• Screw the link member to the servo horn
• Attach the servo module to the link member with double-sided tape
• Screw the servo module holder on the base
• Make the power cable and the communication conversion cable
• Wire the connections, burn in the IDs, and check operation

Precautions

• It may be reassuring to place termination resistors at both ends of the RS-485 wiring.
• When replacing the bottom case, you need to take apart the DF11 4-pin connector once. The wire colors are the same, so be extremely careful not to mix them up.

Assembly Instructions

Please refer to the photo.

Standalone Operation Check Tool: python3 + dicot

dicot (opens in a new tab) is convenient. You can install it with pip3 install dicot.

After reading through the dicot README.md (opens in a new tab), reading the source (opens in a new tab) should help you find the names of the properties you want to access.

Serial devices can be read and written by members of the dialout group, so add your own Ubuntu user account to the dialout group. For example, if the user name is alice, run sudo adduser alice dialout and then restart.

Running on Linux

The RSC-U485 works with the FTDI driver (ftdi_sio), but the standard FTDI driver does not register the RSC-U485. To make it work immediately by hand, run the following command.

$ sudo su
# modrobe ftdi_sio
# echo 1115 0008 > /sys/bus/usb-serial/drivers/ftdi_sio/new_id

To have it recognized automatically on future boots, create a file with any suitable name under /etc/udev/rules.d and write the following in it.

ATTR{idVendor}=="1115", ATTR{idProduct}=="0008", GROUP="dialout", MODE="0660", RUN+="/bin/sh -c '/sbin/modprobe ftdi_sio; /bin/sh -c \"echo 1115 0008\" > /sys/bus/usb-serial/drivers/ftdi_sio/new_id'"

Running on Windows

I believe it should work if you download and install the driver from the Futaba site (opens in a new tab), check which COM port it was assigned, and specify that COM port in dicot.

ros2_control で動かすときのコマンドライン覚書

全軸 torque off (inactive 状態へ遷移)

ros2 service call /controller_manager/set_hardware_component_state controller_manager_msgs/srv/SetHardwareComponentState "{name: fcs0, target_state: {id: 0, label: inactive}}"

全軸 torque enable (active 状態へ遷移)

ros2 service call /controller_manager/set_hardware_component_state controller_manager_msgs/srv/SetHardwareComponentState "{name: fcs0, target_state: {id: 0, label: active}}"

目標角度へ動作（ここでは [0, 0, 0, 0], 単位はラジアン）

ros2 action send_goal /joint_trajectory_controller_fcs4hand2310/follow_joint_trajectory control_msgs/action/FollowJointTrajectory -f "{ trajectory: { joint_names: [ hndj0, hndj1, hndj2, hndj3 ], points : [ { positions: [0, 0, 0, 0], time_from_start: { sec: 0.5 }} ]}}"

About this repository

Script files

├── CMakeLists.txt
├── Readme.md
├── config
│   └── ros2_controllers_fcs4hand2310.yaml
├── launch
│   └── fcs4hand2310.launch.py
├── package.xml
├── pics
│   ├── pict00.jpg
│   ├── pict01.jpg
│   ...
├── step
│   ├── FCS4HAND2310_BASE.STEP
│   ├── FCS4HAND2310_BASE_LID.STEP
│   ...
├── scripts
│   ├── set_angles.py
│   ├── torque_enable.sh
│   └── torque_free.sh
└── urdf
    ├── RS30x_BottomShaft.dae
    ├── fcs4hand2310.xacro
    └── fcs2310.urdf