- Three forces, Three torques (optionally two torques).
- Six degrees of high resolution sensing.
- High transparency with mechanical handle balancing.
The W6D has a full six degrees of freedom and is capable of three forces and three torques. The workspace is similar to the motion of a hand pivoting at the wrist. High stiffness, low backdrive friction, and zero backlash are achieved by directly coupling the output links to the actuators. The lightweight handle is balanced completely over the entire workspace without compromising a low inertia feel. Users can take advantage of the W6D's easy to configure UDP Ethernet connection and open-source firmware and API utilized by Entact.
Workspace and Force
The W6D has been designed specifically for low force small workspace applications. Although still capable of reasonable translation the device is better suited for working in smaller areas. The motion of the device maps well to the movement of a wrist and forearm pivoting at the elbow. Forces range from quite small to large, but only small forces can be applied continuously. The W6D is well suited to applications with delicate force feedback and the occasional force spike.
Low Friction and Mass
Each link in the W6D's mechanism uses a hollow construction. This greatly reduces the perceived mass handling while at the same time maintaining a high level of stiffness. The use of preloaded bearings in each joint also provides low friction and zero backlash.
Tools and Handgrips
The handle interface can easily be adapted to application specific handgrips or tools. Wires for powered handles can be encapsulated in a hollow channel along the upper arms. Additional analog and digital signals are available for use in adapting custom handles.
Gravity balancing is achieved at the W6D's handle. The advantage of this feature is twofold; first the user is not required to hold up the weight of the handle/mechanism and second all available torque can be used exclusively for force feedback. Balancing is achieved via the use of brass counterweights behind the mechanisms arms. A nice benefit of having lightweight arms is the reduction in required counterweight mass keeping the perceived handle mass quite low.
Precise Forces and Torques
Force fidelity is the primary consideration in the W6D's design. Our choice to directly couple the mechanism arms to the actuators enables accurate transmission of force to your hand.
Inside the W6D is an embedded system running a real-time patched version of Linux. The embedded system is based around the popular Gumstix Overo series of computer modules. All firmware source code is available for use and modification to suit your specific application. Our embedded system makes use of Ethernet and UDP for communication with the host. Although unimplemented in software, the embedded system is also capable of serial and USB communication.
One application well suited for the W6D is needle insertion simulation. The forces (and range of motion) followed in a needle insertion procedure map well to the available forces (and range of motion) delivered by the W6D.