Otto Bock SensorHand Speed

SensorHand Speed is a hand prosthetics product developed by Otto Bock.

Description

The device essentially consists of a force and velocity controlled gripper that is controlled by integrated electronics.

In normal operation mode, electrodes that are attached to the user's arm are connected to the hand's interface and provide analog signals that allow gripping operations.

The hand can also be switched to communications mode which allows accessing the device via an RS-232 interface (19200-8-N-1).

Within the communications mode, it offers several sub-modes of operation which differ in their gripping characteristics.

• 0: gripping with soft grip fastening
• 1: hand stops after first grip
• 2: maximum velocity, maximum force will be applied
• 3,4: undocumented

In addition to the operation modes above it is also possible to set the device to a mode in which internal data (measured forces, voltages and currents) is sent over the serial interface every 12 ms. This mode is called the dump mode.

Set of commands

Communications with this device makes use of a frame whose first symbol is the number of the remaining symbols of the current message. The last symbol (which counts for the mentioned number) is the check sum of all previously sent symbols of the current frame (including the length symbol).

The available commands are

• get serial number
• open hand (with speed/force parameter)
• close hand (with speed/force parameter)
• start dump mode
• stop dump mode
• switch mode of operation (see above)

Details about the available commands and the expected responses can be obtained from the driver implementation available here.