Compliant geometry

Compliant geometry

The compliant geometry of the robot allows the body to deform. The side of the body is to be covered with textile. An impact at any point on its textile cover will deform the textile slightly but also tilt the top of the body away from the impact. A compliant body has many safety advantages in populated environments, such as a party or conference reception. Many robots use a mobile outer shell to detect collisions, e.g. in the Rug Warrior (Jones and Flynn, 1993). In ButlerBot however, the body itself s the detector. While compliance has been investigated for couplings and joints (see e.g. Trease et al., 2005; Meyer et al., 2004), we are not aware of other work using the whole body as a compliant system. Inside the robot is a light-weight support structure. The tray of ButlerBot is supported by 4 poles which have foam dampers at the end. Additionally 4 strings stretch from the centre of the tray down to the edge of the base like the stays of a boat mast, see figures 1b and 2. Each string incorporates a spring to allow flexibility. The 4 poles are mounted off-centre, which allows the tray effectively to shake in the horizontal X-Y plane. The springs have a sensor attached (potentiometer Pot in figure 2) in order to measure their extension. This allows estimating the position of the tray at the top and the amplitude and direction of the shaking. There is a sensor in the spring aligned with the X-axis and another sensor in the spring aligned with the Y-axis.