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Wireless Robotic Hand

 Trang Cung, Clarine Chan and Robin Bourge, Department of Mechanical Engineering, University of Ottawa


The goal of this project is to take the motion of a human hand and simulate it by a robotic hand.  This will hopefully help us later to develop a hand rehabilitation device for those who have hand injuries.  Strokes, osteoarthritis and tendinitis can lead to hand disabilities in adults.  A significant amount of stroke survivors suffer from weakness on one side of the body, leaving them with impaired hand function. By replicating the motion of a human hand with a robotic hand, one can take principals of this design and apply the ideas to a hand rehabilitation device.


The design is to convert the bending motion of flex sensors into rotational motion of servomotors that are controlled by flex sensors.  The servomotors will act as actuators to pull and release fish tackle, which is used to control the motion of the robotic fingers.


The wireless robotic hand could potentially be used as a surgical device. The  surgeon will be able to control its movement using the glove, and the robotic hand performs surgery on the patient. Precisely the robotic hand replicates every movement the surgeon makes. The robotic hand can be built in a microscopic size where it can easily fit through very small incisions, which can potentially minimize scarring, of the patient.   Furthermore, it can provide the surgeon with unprecedented control in a minimally invasive environment, and is more hygienic and thus reduces the chances of postoperative infections. 

Additionally, the wireless robotic hand could be found useful in environments where it is dangerous for humans. In space or places such as hazardous radioactive environments is where the robotic hand would be useful.

Flex Sensors


Flex sensors are used to convert the flexing motion of the fingers into rotational motion of the servo motors.  The flex sensors used for the design are 4.5 inches long, which allows it to cover each finger.  The flex sensors are sewed onto the glove.  As the flex sensor bends, this increases its resistance.  This change in resistance is the signal that is sent to the servomotors.  These flex sensors were soldered onto wires for simpler use.  A 15k resistor was also placed in series with each flex sensor in order to protect it.  The flex sensors were powered by the 5V pin on the Arduino.



Wireless Communication

To allow wireless communication between the two Arduinos, two Xbee modules are used.  The Xbee radio allows wireless communication between microcontrollers such as Arduinos, computers, and any system that has a serial port.  The Xbee that we used were XBee 1mW Trace Antenna - Series 1 (802.15.4). The Xbee radios were configured using X-CTU to ensure their settings allowed them to communicate with each other.  In order to attach the Xbee radio directly onto the Arduinos, we used Xbee shields.  Thus two XBees were required; one for each Arduino.



Two Arduino Uno Atmega 328 were used.  One Arduino takes the signals from the flex sensors and transmits this signal to the other Arduino which contains the servomotors.  The Arduino which contains the servomotors is programmed to receive the signal and convert the signal into a rotating motion of the servo motors.  The higher the resistance on the flex sensor, the more the servos will turn.  The Arduinos are programmed using the Arduino software.




The servomotors used for this design is the standard sized Hitec HS-422. It operate at a voltage of 4.6-6.0V and is able to turn 180.  The servomotors pull on the fish wire which causes the robotic hand to flex.  The servomotors were powered by the 5V from the Arduino.  The maximum amount of torque that these servos are able to generate is 56.93 oz-in.




Two 9-V batteries are used to power each arduino.

The Robotic Hand

Pin joint mechanical parts was as the main frame of the fingers, we decided to use bicycle chains which allows the fingers to have natural full range of motion. These linkages are set into a spring which allows the fingers to return to their resting position when the line is loosened. The bicycle chain design pin joints were prevented from turning at all but 2 joints to create the jointed motion of actual fingers. The size and length of the fingers and palm for our project is very similar to the size of an average human hand. 

Moreover, to combine all the fingers together to form a hand, we used 2 aluminum metal sheet and sandwiched the fingers using screws. Screws that were used to fix the fingers double as points for the strings to bend around. This minimizes the tangling of the wire. The robotic hand is also very lightweight, durable, and portable/compact due to the materials used and the way it is constructed.