Inception Drive: ultra-compact variable transmission for robotics | SRI International

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Inception Drive: ultra-compact variable transmission for robotics

A novel, ultra-compact variable transmission promises to dramatically increase efficiency for robotics systems and allow for safer human-robot interaction.

The latest breakthrough from SRI Robotics is a novel ultra-compact, infinitely variable transmission that is an order of magnitude smaller and lighter than existing technologies. Inception Drive is a new transmission that can reverse the direction of the output relative to input without clutches or extra stages, dramatically increasing total system efficiency in applications including robotics, transportation, and heavy industry.

Traditional fixed ratio transmissions have a complex relationship to total system efficiency. It is not uncommon for an increased transmission efficiency to cause a reduction in total system efficiency. For instance, this happens when an efficient actuator is asked to hold a position under load for a period of time, causing the motor to see high torques with no mechanical work being done. Inception Drive can transcend this problem by switching to very high ratios, reducing or eliminating motor torque during static lifts.

With high torque and power density, Inception Drive is small enough to replace fixed-ratio transmissions in robots, enabling energy savings of up to 50 percent in many applications. In addition, the transmission’s reversible output can allow for the reduction of the number of motors required in a robot, thereby significantly reducing the overall weight and cost of the system.

The variable ratio transmission also allows for safer human-robot interaction through variable impedance control. Traditionally robots have a high transmission ratio in order to pick up or move heavy items, resulting in a rigid robotic system that is dangerous for human interaction. Because the transmission ratio is adjustable, the impedance of the system can be raised for specific tasks and then lowered for human safety.