While human interactive robots have to evolve more to populate our homes and of-fices, they already packed their luggages and left research labs to apply for jobs in factories. This is the case of Baxter [64] (fig. 1.16). Whereas traditional industrial robots perform one specific task with superhuman speed and precision, Baxter is nei-ther particularly fast nor particularly precise. But it is able to perform any job that involves picking stuff up and putting it down somewhere else while simultaneously adapting to changes in its environment, like a misplaced part or a conveyor belt that suddenly changes speed. In addition, Baxter is designed to be inherently safe. With their fast, powerful motors and hefty limbs, industrial robots are typically kept fenced off from people. Baxter is limited speed and lower weight (about 75 kilograms or as much as an average adult man) meaning that it can operate right alongside human workers. There are two other major barriers to the adoption of industrial robots that Baxter’s creators want to overcome: ease of use and cost. As for the first, Baxter does not rely on custom programming to perform new tasks. Once it is wheeled into place and plugged into an ordinary power outlet, a person with no robotics experience can program a new task simply by moving Baxter’s arms around and following prompts on its user-friendly interface (which doubles as the robot’s face). Instead of actually programming the robot, it is simply shown what to do. To show Baxter how to take an object out of a box and put it on a conveyor belt, you start by grabbing the robot by the wrist to get its attention. Baxter will stop whatever it is doing and look at you with the calm, confident eyes displayed on its LCD. You then move the arm over
1.3. Hiring Social Robots 33
to the box and use buttons and a knob on the arm to navigate a series of menus on the LCD, telling the robot to use its vision to find the object. Finally, you move the arm over to the conveyor and push some more buttons to let Baxter know that this is where you want the object dropped off. Baxter even nods its head, as if to say, “I get it”. Pressing the play button makes the robot execute the task on its own.
Furthermore, while a traditional two-armed robot will typically cost hundreds of thousands of dollars (including sensors and programming), Baxter costs just $22000.
To achieve that, the robot was designed from scratch. Underneath Baxter’s plastic exterior lie thousands of ingeniously engineered parts and materials that enable the robot to do what it does for the cost of a midsize car. One of Baxter’s key features is compliance. A robot is said to be compliant when it is not completely rigid and when it can sense and control the forces it applies to things. Through compliance Baxter can get feedback during the execution of tasks and be safe around humans.
Baxter is not the only human interactive robot designed to work in manufacture.
Swiss-Swedish giant ABB has developed a dual-arm prototype, reportedly for assem-bly applications. Japanese firm Kawada Industries has a similar robot named Nextage.
They might not cost as little as Baxter, but they will likely be able to perform high-precision tasks that Baxter can not do, like assembling electronics boards, another potentially huge market for robotic automation. Other start-ups are also looking to enter the low-cost robotics market. Robots are ready to work with us and are looking forward to living with us.
34 Chapter 1. Toward Social Robots
Figure 1.16: Baxter main functionalities.
Chapter 2
Development of Human-Robot Physical Interaction Tasks
The research activities described in this dissertation have been focused on the field of physical human-robot interaction. In order to investigate issues arising in the physi-cal interaction between a human and a robot I developed robot prototypes that were able to hand over objects to humans and receive object from humans. Handing over objects to a partner is a very common task which is necessary for diverse interactive and collaborative activities. Furthermore, the approaches used to enable human-robot handover and the findings from user studies can be used as a baseline to develop ef-fective human-robot interaction systems.
2.1 Handoff of an object between human and robot
By handoff (or handover) we mean the transfer of an object from a giver to a receiver.
Handoffs are an important function in everyday life. For humans, handoffs are an easy task and are usually routine rather than deliberative. Even if humans perform several handoffs on a daily basis with different types of objects and in different situations and roles, they usually cannot remember how exactly they performed the handoff. This fact is an indication of how routinary and innate handoff tasks are for humans. In
36 Chapter 2. Development of Human-Robot Physical Interaction Tasks
addition, motions of the giver and the receiver are often synchronized and they work together until the transfer of the object is complete [51]. It turns out that such an easy task for humans is hard for robots. In order to complete the handoff a robot should perform several challenging subtasks, such as detecting when to give or receive the object (e.g. performing gesture recognition), identifying the object and synchroniz-ing its movement with the partner without hurtsynchroniz-ing the partner itself. Dependsynchroniz-ing on the shape of the object and the movements of the partner the robot needs to compute sophisticated trajectory plans to complete the handoff. Each of these subtasks is itself an active area of research, and yet all must be accomplished simultaneously to pro-duce a good handoff system.
I address this task because it is a common and highly collaborative task and I want to investigate how the recent availability of technologies that provide advanced human motion perception, such as Microsoft Kinect, enable the development of new robotic systems for effective human-robot collaboration. The Kinect is a low cost RGB-D camera that records two images, a RGB image and a depth image. These images can be used by the software bundled with the Kinect to detect and track humans in a fast and reliable way. This new technology enables the active participation of robots in human-robot handoffs, previously unfeasible, by improving the perception capabili-ties of robots. However, Kinect-based human tracking is not perfect and is sensitive to fast human movement, non-frontal views of humans, and situations where the hu-man is near other objects. Thus, while the Kinect provides improved perception to the robot, it is far from providing the same high-quality perception available to human.
In addition to study the technical solution that enable advanced human-robot interac-tion I aim to investigate how people feel when they physically interact with a robot that is able to perceive their presence and their motion and uses this information to behave proactively.
In this chapter two human-robot hando f f systems developed during this thesis work are presented. The first system enables human to robot handoffs, the second one en-ables robot to human handoffs. In Both systems robots are human aware.