A Brief Description of CMM Touch Probe
Outputting the digital blueprint into a final fast prototype is important, but inputting a hand-made sculpture into the computer is as important in the creative process. There are many high-tech electronic devices that can help the artist generate form from his/her sculpture quickly. This process is called "reverse-engineering of prototypes", and it is often utilized a digitizer to accurately measure an object. A digitizer is considered to be a touch probe device, because it requires touching an object to record it's coordination. The concept of the touch probe involves a measuring tip attached by several limbs with rotational joints. The design of the joints and limbs determines the reach of the touch probe. The measuring tip of the touch probe is used to measure the exact coordinates on the surface of the scanned object. A small desktop model can measure an object of up to about 4' to 5'. A large industrial model can measure a much larger object. Optical encoders are embedded in each joint to determine the angle. The touch probe is very intuitive to use, because the user can easily place the measuring tip on the point of the surface to be measured. The process can be very time consuming if a lot of points need to be measured.
Touch Probes have a measurement tip attached via several limbs and joints. The location of the tip relative to the base can be calculated by knowing the limb lengths and the joint angles. The configuration of the joints and limbs will determine the reach and the ability of the touch probe. Touch probes can range from small desktop models capable of measuring a 50" sphere to large industrial models that can measure up to a 12' sphere. They typically have up to seven degrees of freedom. Optical encoders are used at each joint to determine the angle.
An advantage of touch probes is that they are intuitive to use. You move the tip to the location you want to measure, and tell the computer to acquire a point. Touch probes can reach behind and into objects. The disadvantage is that it can be time-consuming to measure a lot of points. If the tip used is not a point, then offset calculations are required.
One effective way of using a touch probe is to use MicroScribe digitizer? by Immersion, or Portable Arms by AXILA Inc., or the Faro Arms? by Faro Technologies to obtain the coordinates of the control points to generate the surface from a real physical model. There are eight critical parts of the digitizer: base, shoulder, counterweight, upper arm, elbow, lower arm, wrist, and sensitive stylus. The foot pedal controls the digitizer's operation and frees your hands to hold the stylus.
There are many different types of digitizers; however, any digitizer or any similar device provides an economical and accurate way to convert a built form into the computer. The only drawback is that the object has to be small enough to be digitized within full extension of the digitizer's arm. The method of digitizing a larger object requires the challenge or larger digitizer. Setting up reference points is the first step to successfully digitizing an object. The digitizer detects the points of cross-section on the surface of the object, and then converts the data into computer software. Later the user can use the u-loft command or a similar command to generate a NURB (Non-Uniform Rational B-spline) surface.
Touch Probes have a measurement tip attached via several limbs and joints. The location of the tip relative to the base can be calculated by knowing the limb lengths and the joint angles. The configuration of the joints and limbs will determine the reach and the ability of the touch probe. Touch probes can range from small desktop models capable of measuring a 50" sphere to large industrial models that can measure up to a 12' sphere. They typically have up to seven degrees of freedom. Optical encoders are used at each joint to determine the angle.
An advantage of touch probes is that they are intuitive to use. You move the tip to the location you want to measure, and tell the computer to acquire a point. Touch probes can reach behind and into objects. The disadvantage is that it can be time-consuming to measure a lot of points. If the tip used is not a point, then offset calculations are required.
One effective way of using a touch probe is to use MicroScribe digitizer? by Immersion, or Portable Arms by AXILA Inc., or the Faro Arms? by Faro Technologies to obtain the coordinates of the control points to generate the surface from a real physical model. There are eight critical parts of the digitizer: base, shoulder, counterweight, upper arm, elbow, lower arm, wrist, and sensitive stylus. The foot pedal controls the digitizer's operation and frees your hands to hold the stylus.
There are many different types of digitizers; however, any digitizer or any similar device provides an economical and accurate way to convert a built form into the computer. The only drawback is that the object has to be small enough to be digitized within full extension of the digitizer's arm. The method of digitizing a larger object requires the challenge or larger digitizer. Setting up reference points is the first step to successfully digitizing an object. The digitizer detects the points of cross-section on the surface of the object, and then converts the data into computer software. Later the user can use the u-loft command or a similar command to generate a NURB (Non-Uniform Rational B-spline) surface.