ChainFORM

ChainFORM is a modular hardware system for designing linear shape-changing interfaces. Each module is developed based on a servo motor with added flexible circuit board, and is capable of touch detection, visual output, angular sensing, and motor actuation. 

Each module can communicate with other modules linearly, allowing users and designers to adjust and customize the length of the interface. The hardware system has a wide range of applications, including line-based shape changing display, reconfigurable stylus, rapid prototyping tool for actuated crafts, and a customizable haptic glove. 

The module can detect tangible interactions by users. Specif-ically, the angular deformation and the way users touch themodules can be detected. The ChainFORM module can pro-vide several outputs.  One is motor actuation, it can changethe angle of the joint and also torque can be controlled to lock the joint or loose so that user can deform by their hands and also feel different stiffness as tactile feedback. The color of the surface of each module can be displayed with LEDs toprovide visual feedback. 

System Design

The overall system exists of a chain of integrated modules, a master board and a software on a computer. The master module contains a Teensy 3.2 with an ARM Cortex-M4(MK20DX256VLH7, Freescale). The master coordinates the communications between the modules and shuttles data to thecomputer over USB. The software was developed using Processing on OSX computer.

Module Design

The module of the system is made of three components;  a circuit board, a 3D printed bracket and a servo motor. The motor is placed inside the 3D printed bracket and the bracket provides a mechanical connection for joining to another module. Some parts of the circuit board have flexible hinges ,  so that it can be wrapped around the 3D printed bracket which incorporates the motor. The servo motor is a HS-5035HD (Hitec)

The circuit board has an ATmega328p (Atmel) microcontroller, which is the “brain” of the module. MTCH6102 (Microchip) was used to perform capacitive sensing.  A  small solid-state relay, G3VM-21UR11 (OMRON) was used to turnon/off the torque of servo motor.   An array of 8 Neopixels Mini (Adafruit) was used for the LED display covering a single surface of a module. The circuit board is designed to integrate six capacitive sensing surfaces, so that every surface of the module is capable of touch sensing.