Testing

Testing different grasps is essential for customizing a gripper to an object. The SDM finger activity provides students with an option to prepare two different designs of fingers. From there, this fabrication guide details the variations that can be accomplished within the electronic and manual grippers.

 

Problem-Based Approach

The following steps describe an overview of the problem-based approach on which this activity focuses.

 

Step 1: Select or assign an object

Objects can be selected or assigned to students within the activity. Typically, variations in shape, size and weight will influence the needs of the gripper designs. Students can work in groups or alone to start designing for the requirements of their particular object.

 

Step 2: Make a hypothesis

Before building the gripper, students should form a hypothesis regarding what would constitute a suitable grasp for the object assigned or chosen. Sketches, discussion and prototypes can also be used to help map out the best possible solution. Factors that will need to be chosen within the electronic gripper include:

  1. Most suitable finger design (this is an option included when building the SDM fingers)
  2. Number of fingers required
  3. Distance and orientation between the fingers
  4. Angle of each finger via the cardboard bases

Factors determined within the manual gripper activity:

  1. Most suitable finger design (this is an option included when building the SDM fingers)
  2. Number of fingers required
  3. Distance and orientation between the fingers

 

Step 3: Build the gripper accordingly and test the hypothesis

Students should build their grippers according to the designs they sketched, discussed or prototyped at the start of the activity. Upon testing, results should be recorded in order to make informed design modifications for the next version.

 

Step 4: Modify as needed according to results of step 3

Adjusting the fingers on Electronic Gripper:

The carboard finger bases that attach the fingers to the electronic control board can be easily reconfigured using the base screw and nut that secures the base to the pegboard. Simply unscrew and place in a new configuration. To ensure proper placement of the string through the pulley, make sure to use the eye screws to correctly route the string and limit tension on the finger bases.

Cardboard bases can also be changed if the angle of the finger requires alteration.

electronic_grippers_versions

 

Adjusting the fingers on Manual Gripper

The distance between the finger can be adjusted by using tubes of different diameters. The angle between the fingers can be adjusted by moving the fingers up and down on the tube and locking the zip tie in correct position. You can add up to four fingers on the same tube of diameter 1 inch and more for larger diameter tubes.

gripper_variations.jpg